Elixir: Switch Poison to Jason (#16061)

* Switch Poison to Jason * generate-samples.sh * Finalize Poison -> Jason switch * parse date-time values to Elixir DateTime * improve formatting in various places, so there's less changes by `mix format` later * fix Java version in flake.nix * Use List.delete/2 instead of Enum.reject/2 for performance reasons * mix format test/* * Install dialyxir and fix reported issues * Fix RequestBuilder.decode/2 hardcoded module name * Update docs * Revert changes to API spec (HTTP -> HTTPS) * Revert uneeded change to Elixir code generator * Use HTTP in Elixir tests HTTPS doesn't work for folks who setup petstore.swagger.io as described in docs/faq-contributing.md. --------- Co-authored-by: Wojciech Piekutowski <wojciech@piekutowski.net>
2025-05-12 04:30:51 +00:00 · 2023-07-20 18:36:50 +02:00 · 2023-07-20 18:36:50 +02:00 · 4ece8e992a
commit 4ece8e992a
parent ddc2b3e560
71 changed files with 625 additions and 351 deletions
--- a/docs/generators/elixir.md
+++ b/docs/generators/elixir.md
@ -48,7 +48,6 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 <li>AnyType</li>
 <li>Atom</li>
 <li>Boolean</li>
-<li>DateTime</li>
 <li>Decimal</li>
 <li>Float</li>
 <li>Integer</li>
--- a/flake.nix
+++ b/flake.nix
@ -13,7 +13,7 @@
        devShells.default = pkgs.mkShell
          {
            buildInputs = with pkgs;[
-              jdk8
+              jdk11
              maven
            ];
          };
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
@ -59,9 +59,10 @@ public class ElixirClientCodegen extends DefaultCodegen {
    String supportedElixirVersion = "1.10";
    List<String> extraApplications = Arrays.asList(":logger");
    List<String> deps = Arrays.asList(
-            "{:tesla, \"~> 1.4\"}",
-            "{:poison, \"~> 3.0\"}",
-            "{:ex_doc, \"~> 0.28\", only: :dev, runtime: false}"
+            "{:tesla, \"~> 1.7\"}",
+            "{:jason, \"~> 1.4\"}",
+            "{:ex_doc, \"~> 0.30\", only: :dev, runtime: false}",
+            "{:dialyxir, \"~> 1.3\", only: [:dev, :test], runtime: false}"
    );

    public ElixirClientCodegen() {
@ -194,7 +195,6 @@ public class ElixirClientCodegen extends DefaultCodegen {
                        "AnyType",
                        "Tuple",
                        "PID",
-                        "DateTime",
                        "map()", // This is a workaround, since the DefaultCodeGen uses our elixir TypeSpec datetype to evaluate the primitive
                        "any()"
                )
@ -210,7 +210,7 @@ public class ElixirClientCodegen extends DefaultCodegen {
        typeMapping.put("string", "String");
        typeMapping.put("byte", "Integer");
        typeMapping.put("boolean", "Boolean");
-        typeMapping.put("Date", "DateTime");
+        typeMapping.put("Date", "Date");
        typeMapping.put("DateTime", "DateTime");
        typeMapping.put("file", "String");
        typeMapping.put("map", "Map");
@ -575,7 +575,12 @@ public class ElixirClientCodegen extends DefaultCodegen {
        } else if (ModelUtils.isBooleanSchema(p)) {
            return "boolean()";
        } else if (!StringUtils.isEmpty(p.get$ref())) {
-            return this.moduleName + ".Model." + super.getTypeDeclaration(p) + ".t";
+            switch (super.getTypeDeclaration(p)) {
+                case "String":
+                    return "String.t";
+                default:
+                    return this.moduleName + ".Model." + super.getTypeDeclaration(p) + ".t";
+            }
        } else if (ModelUtils.isFileSchema(p)) {
            return "String.t";
        } else if (ModelUtils.isStringSchema(p)) {
@ -662,28 +667,23 @@ public class ElixirClientCodegen extends DefaultCodegen {
        }

        public String decodedStruct() {
-            // Let Poison decode the entire response into a generic blob
+            // Let Jason decode the entire response into a generic blob
            if (isMap) {
                return "%{}";
            }
+
            // Primitive return type, don't even try to decode
            if (baseType == null || (containerType == null && primitiveType)) {
                return "false";
            } else if (isArray && languageSpecificPrimitives().contains(baseType)) {
                return "[]";
            }
+
            StringBuilder sb = new StringBuilder();
-            if (isArray) {
-                sb.append("[");
-            }
-            sb.append("%");
            sb.append(moduleName);
            sb.append(".Model.");
            sb.append(baseType);
-            sb.append("{}");
-            if (isArray) {
-                sb.append("]");
-            }
+
            return sb.toString();
        }

@ -768,6 +768,24 @@ public class ElixirClientCodegen extends DefaultCodegen {
            this.replacedPathName = replacedPathName;
        }

+        private void translateBaseType(StringBuilder returnEntry, String baseType) {
+            switch (baseType) {
+                case "AnyType":
+                    returnEntry.append("any()");
+                    break;
+                case "Boolean":
+                    returnEntry.append("boolean()");
+                    break;
+                case "Float":
+                    returnEntry.append("float()");
+                    break;
+                default:
+                    returnEntry.append(baseType);
+                    returnEntry.append(".t");
+                    break;
+            }
+        }
+
        public String typespec() {
            StringBuilder sb = new StringBuilder("@spec ");
            sb.append(underscore(operationId));
@ -793,12 +811,7 @@ public class ElixirClientCodegen extends DefaultCodegen {
                        returnEntry.append(".Model.");
                    }

-                    if (exResponse.baseType.equals("AnyType")) {
-                        returnEntry.append("any()");
-                    }else {
-                        returnEntry.append(exResponse.baseType);
-                        returnEntry.append(".t");
-                    }
+                    translateBaseType(returnEntry, exResponse.baseType);
                } else {
                    if (exResponse.containerType.equals("array") ||
                            exResponse.containerType.equals("set")) {
@ -808,12 +821,8 @@ public class ElixirClientCodegen extends DefaultCodegen {
                            returnEntry.append(".Model.");
                        }

-                        if (exResponse.baseType.equals("AnyType")) {
-                            returnEntry.append("any())");
-                        }else {
-                            returnEntry.append(exResponse.baseType);
-                            returnEntry.append(".t)");
-                        }
+                        translateBaseType(returnEntry, exResponse.baseType);
+                        returnEntry.append(")");
                    } else if (exResponse.containerType.equals("map")) {
                        returnEntry.append("map()");
                    }
--- a/modules/openapi-generator/src/main/resources/elixir/connection.ex.mustache
+++ b/modules/openapi-generator/src/main/resources/elixir/connection.ex.mustache
@ -216,7 +216,7 @@ defmodule {{moduleName}}.Connection do

    tesla_options = Application.get_env(:tesla, __MODULE__, [])
    middleware = Keyword.get(tesla_options, :middleware, [])
-    json_engine = Keyword.get(tesla_options, :json, Poison)
+    json_engine = Keyword.get(tesla_options, :json, Jason)

    user_agent =
      Keyword.get(
--- a/modules/openapi-generator/src/main/resources/elixir/deserializer.ex.mustache
+++ b/modules/openapi-generator/src/main/resources/elixir/deserializer.ex.mustache
@ -4,37 +4,81 @@ defmodule {{moduleName}}.Deserializer do
  Helper functions for deserializing responses into models
  """

+  @jason_decode_opts [keys: :strings]
+
+  def jason_decode(json) do
+    Jason.decode(json, @jason_decode_opts)
+  end
+
+  def jason_decode(json, module) do
+    json
+    |> jason_decode()
+    |> case do
+      {:ok, decoded} -> {:ok, to_struct(decoded, module)}
+      {:error, _} = error -> error
+    end
+  end
+
  @doc """
  Update the provided model with a deserialization of a nested value
  """
-  @spec deserialize(struct(), :atom, :atom, struct(), keyword()) :: struct()
-  def deserialize(model, field, :list, mod, options) do
+  @spec deserialize(struct(), atom(), :date | :datetime | :list | :map | :struct, module()) ::
+          struct()
+  def deserialize(model, field, :list, module) do
    model
-    |> Map.update!(field, &(Poison.Decode.decode(&1, Keyword.merge(options, [as: [struct(mod)]]))))
+    |> Map.update!(field, fn
+      nil ->
+        nil
+
+      list ->
+        Enum.map(list, &to_struct(&1, module))
+    end)
  end

-  def deserialize(model, field, :struct, mod, options) do
+  def deserialize(model, field, :struct, module) do
    model
-    |> Map.update!(field, &(Poison.Decode.decode(&1, Keyword.merge(options, [as: struct(mod)]))))
+    |> Map.update!(field, fn
+      nil ->
+        nil
+
+      value ->
+        to_struct(value, module)
+    end)
  end

-  def deserialize(model, field, :map, mod, options) do
+  def deserialize(model, field, :map, module) do
    maybe_transform_map = fn
      nil ->
        nil

      existing_value ->
        Map.new(existing_value, fn
-          {key, val} ->
-            {key, Poison.Decode.decode(val, Keyword.merge(options, as: struct(mod)))}
+          {key, value} ->
+            {key, to_struct(value, module)}
        end)
    end

    Map.update!(model, field, maybe_transform_map)
  end

-  def deserialize(model, field, :date, _, _options) do
+  def deserialize(model, field, :date, _) do
    value = Map.get(model, field)
+
+    case is_binary(value) do
+      true ->
+        case Date.from_iso8601(value) do
+          {:ok, date} -> Map.put(model, field, date)
+          _ -> model
+        end
+
+      false ->
+        model
+    end
+  end
+
+  def deserialize(model, field, :datetime, _) do
+    value = Map.get(model, field)
+
    case is_binary(value) do
      true ->
        case DateTime.from_iso8601(value) do
@ -46,4 +90,23 @@ defmodule {{moduleName}}.Deserializer do
        model
    end
  end
+
+  defp to_struct(map_or_list, module)
+  defp to_struct(nil, _), do: nil
+
+  defp to_struct(list, module) when is_list(list) and is_atom(module) do
+    Enum.map(list, &to_struct(&1, module))
+  end
+
+  defp to_struct(map, module) when is_map(map) and is_atom(module) do
+    model = struct(module)
+
+    model
+    |> Map.keys()
+    |> List.delete(:__struct__)
+    |> Enum.reduce(model, fn field, acc ->
+      Map.replace(acc, field, Map.get(map, Atom.to_string(field)))
+    end)
+    |> module.decode()
+  end
 end
--- a/modules/openapi-generator/src/main/resources/elixir/mix.exs.mustache
+++ b/modules/openapi-generator/src/main/resources/elixir/mix.exs.mustache
@ -9,7 +9,9 @@ defmodule {{moduleName}}.Mixfile do
      build_embedded: Mix.env() == :prod,
      start_permanent: Mix.env() == :prod,
      package: package(),
-      description: "{{appDescription}}",
+      description: """
+      {{appDescription}}
+      """,
      deps: deps()
    ]
  end
--- a/modules/openapi-generator/src/main/resources/elixir/model.mustache
+++ b/modules/openapi-generator/src/main/resources/elixir/model.mustache
@ -4,7 +4,7 @@
  {{&description}}
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    {{#vars}}{{#atom}}{{&baseName}}{{/atom}}{{^-last}},
    {{/-last}}{{/vars}}
@ -14,22 +14,21 @@
    {{#vars}}{{#atom}}{{&baseName}}{{/atom}} => {{{datatype}}}{{#isNullable}} | nil{{/isNullable}}{{^isNullable}}{{^required}} | nil{{/required}}{{/isNullable}}{{^-last}},
    {{/-last}}{{/vars}}
  }
-end

-defimpl Poison.Decoder, for: {{&moduleName}}.Model.{{&classname}} do
 {{#hasComplexVars}}
-  import {{&moduleName}}.Deserializer
-  def decode(value, options) do
+  alias {{&moduleName}}.Deserializer
+
+  def decode(value) do
    value
    {{#vars}}
    {{^isPrimitiveType}}
-    {{#baseType}}|> deserialize({{#atom}}{{&baseName}}{{/atom}}, {{#isArray}}:list, {{&moduleName}}.Model.{{{items.baseType}}}{{/isArray}}{{#isMap}}:map, {{&moduleName}}.Model.{{{items.baseType}}}{{/isMap}}{{#isDate}}:date, nil{{/isDate}}{{#isDateTime}}:date, nil{{/isDateTime}}{{^isDate}}{{^isDateTime}}{{^isMap}}{{^isArray}}:struct, {{moduleName}}.Model.{{baseType}}{{/isArray}}{{/isMap}}{{/isDateTime}}{{/isDate}}, options)
+    {{#baseType}} |> Deserializer.deserialize({{#atom}}{{&baseName}}{{/atom}}, {{#isArray}}:list, {{&moduleName}}.Model.{{{items.baseType}}}{{/isArray}}{{#isMap}}:map, {{&moduleName}}.Model.{{{items.baseType}}}{{/isMap}}{{#isDate}}:date, nil{{/isDate}}{{#isDateTime}}:datetime, nil{{/isDateTime}}{{^isDate}}{{^isDateTime}}{{^isMap}}{{^isArray}}:struct, {{moduleName}}.Model.{{baseType}}{{/isArray}}{{/isMap}}{{/isDateTime}}{{/isDate}})
    {{/baseType}}
    {{/isPrimitiveType}}
    {{/vars}}
 {{/hasComplexVars}}
 {{^hasComplexVars}}
-  def decode(value, _options) do
+  def decode(value) do
    value
 {{/hasComplexVars}}
  end
--- a/modules/openapi-generator/src/main/resources/elixir/request_builder.ex.mustache
+++ b/modules/openapi-generator/src/main/resources/elixir/request_builder.ex.mustache
@ -94,7 +94,7 @@ defmodule {{moduleName}}.RequestBuilder do
      Tesla.Multipart.add_field(
        multipart,
        key,
-        Poison.encode!(value),
+        Jason.encode!(value),
        headers: [{:"Content-Type", "application/json"}]
      )
    end)
@ -146,8 +146,8 @@ defmodule {{moduleName}}.RequestBuilder do
    Map.put_new(request, :body, "")
  end

-  @type status_code :: 100..599
-  @type response_mapping :: [{status_code, struct() | false}]
+  @type status_code :: :default | 100..599
+  @type response_mapping :: [{status_code, false | %{} | module()}]

  @doc """
  Evaluate the response from a Tesla request.
@ -185,5 +185,11 @@ defmodule {{moduleName}}.RequestBuilder do

  defp decode(%Tesla.Env{} = env, false), do: {:ok, env}

-  defp decode(%Tesla.Env{body: body}, struct), do: Poison.decode(body, as: struct)
+  defp decode(%Tesla.Env{body: body}, %{}) do
+    {{moduleName}}.Deserializer.jason_decode(body)
+  end
+
+  defp decode(%Tesla.Env{body: body}, module) do
+    {{moduleName}}.Deserializer.jason_decode(body, module)
+  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/another_fake.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/another_fake.ex
@ -36,7 +36,7 @@ defmodule OpenapiPetstore.Api.AnotherFake do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Client{}}
+      {200, OpenapiPetstore.Model.Client}
    ])
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/default.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/default.ex
@ -32,7 +32,7 @@ defmodule OpenapiPetstore.Api.Default do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {:default, %OpenapiPetstore.Model.FooGetDefaultResponse{}}
+      {:default, OpenapiPetstore.Model.FooGetDefaultResponse}
    ])
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/fake.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/fake.ex
@ -33,7 +33,7 @@ defmodule OpenapiPetstore.Api.Fake do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.FakeBigDecimalMap200Response{}}
+      {200, OpenapiPetstore.Model.FakeBigDecimalMap200Response}
    ])
  end

@ -61,7 +61,7 @@ defmodule OpenapiPetstore.Api.Fake do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.HealthCheckResult{}}
+      {200, OpenapiPetstore.Model.HealthCheckResult}
    ])
  end

@ -117,7 +117,7 @@ defmodule OpenapiPetstore.Api.Fake do
  - `{:ok, boolean()}` on success
  - `{:error, Tesla.Env.t}` on failure
  """
-  @spec fake_outer_boolean_serialize(Tesla.Env.client, keyword()) :: {:ok, Boolean.t} | {:error, Tesla.Env.t}
+  @spec fake_outer_boolean_serialize(Tesla.Env.client, keyword()) :: {:ok, boolean()} | {:error, Tesla.Env.t}
  def fake_outer_boolean_serialize(connection, opts \\ []) do
    optional_params = %{
      :body => :body
@ -169,7 +169,7 @@ defmodule OpenapiPetstore.Api.Fake do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.OuterComposite{}}
+      {200, OpenapiPetstore.Model.OuterComposite}
    ])
  end

@ -187,7 +187,7 @@ defmodule OpenapiPetstore.Api.Fake do
  - `{:ok, float()}` on success
  - `{:error, Tesla.Env.t}` on failure
  """
-  @spec fake_outer_number_serialize(Tesla.Env.client, keyword()) :: {:ok, Float.t} | {:error, Tesla.Env.t}
+  @spec fake_outer_number_serialize(Tesla.Env.client, keyword()) :: {:ok, float()} | {:error, Tesla.Env.t}
  def fake_outer_number_serialize(connection, opts \\ []) do
    optional_params = %{
      :body => :body
@ -269,7 +269,7 @@ defmodule OpenapiPetstore.Api.Fake do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.OuterObjectWithEnumProperty{}}
+      {200, OpenapiPetstore.Model.OuterObjectWithEnumProperty}
    ])
  end

@ -391,7 +391,7 @@ defmodule OpenapiPetstore.Api.Fake do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Client{}}
+      {200, OpenapiPetstore.Model.Client}
    ])
  end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/fake_classname_tags123.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/fake_classname_tags123.ex
@ -36,7 +36,7 @@ defmodule OpenapiPetstore.Api.FakeClassnameTags123 do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Client{}}
+      {200, OpenapiPetstore.Model.Client}
    ])
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/pet.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/pet.ex
@ -105,7 +105,7 @@ defmodule OpenapiPetstore.Api.Pet do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, [%OpenapiPetstore.Model.Pet{}]},
+      {200, OpenapiPetstore.Model.Pet},
      {400, false}
    ])
  end
@ -137,7 +137,7 @@ defmodule OpenapiPetstore.Api.Pet do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, [%OpenapiPetstore.Model.Pet{}]},
+      {200, OpenapiPetstore.Model.Pet},
      {400, false}
    ])
  end
@ -168,7 +168,7 @@ defmodule OpenapiPetstore.Api.Pet do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Pet{}},
+      {200, OpenapiPetstore.Model.Pet},
      {400, false},
      {404, false}
    ])
@ -283,7 +283,7 @@ defmodule OpenapiPetstore.Api.Pet do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.ApiResponse{}}
+      {200, OpenapiPetstore.Model.ApiResponse}
    ])
  end

@ -321,7 +321,7 @@ defmodule OpenapiPetstore.Api.Pet do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.ApiResponse{}}
+      {200, OpenapiPetstore.Model.ApiResponse}
    ])
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/store.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/store.ex
@ -95,7 +95,7 @@ defmodule OpenapiPetstore.Api.Store do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Order{}},
+      {200, OpenapiPetstore.Model.Order},
      {400, false},
      {404, false}
    ])
@ -128,7 +128,7 @@ defmodule OpenapiPetstore.Api.Store do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Order{}},
+      {200, OpenapiPetstore.Model.Order},
      {400, false}
    ])
  end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/user.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/user.ex
@ -159,7 +159,7 @@ defmodule OpenapiPetstore.Api.User do
    connection
    |> Connection.request(request)
    |> evaluate_response([
-      {200, %OpenapiPetstore.Model.User{}},
+      {200, OpenapiPetstore.Model.User},
      {400, false},
      {404, false}
    ])
--- a/samples/client/petstore/elixir/lib/openapi_petstore/connection.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/connection.ex
@ -153,7 +153,7 @@ defmodule OpenapiPetstore.Connection do

    tesla_options = Application.get_env(:tesla, __MODULE__, [])
    middleware = Keyword.get(tesla_options, :middleware, [])
-    json_engine = Keyword.get(tesla_options, :json, Poison)
+    json_engine = Keyword.get(tesla_options, :json, Jason)

    user_agent =
      Keyword.get(
--- a/samples/client/petstore/elixir/lib/openapi_petstore/deserializer.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/deserializer.ex
@ -6,37 +6,81 @@ defmodule OpenapiPetstore.Deserializer do
  Helper functions for deserializing responses into models
  """

+  @jason_decode_opts [keys: :strings]
+
+  def jason_decode(json) do
+    Jason.decode(json, @jason_decode_opts)
+  end
+
+  def jason_decode(json, module) do
+    json
+    |> jason_decode()
+    |> case do
+      {:ok, decoded} -> {:ok, to_struct(decoded, module)}
+      {:error, _} = error -> error
+    end
+  end
+
  @doc """
  Update the provided model with a deserialization of a nested value
  """
-  @spec deserialize(struct(), :atom, :atom, struct(), keyword()) :: struct()
-  def deserialize(model, field, :list, mod, options) do
+  @spec deserialize(struct(), atom(), :date | :datetime | :list | :map | :struct, module()) ::
+          struct()
+  def deserialize(model, field, :list, module) do
    model
-    |> Map.update!(field, &(Poison.Decode.decode(&1, Keyword.merge(options, [as: [struct(mod)]]))))
+    |> Map.update!(field, fn
+      nil ->
+        nil
+
+      list ->
+        Enum.map(list, &to_struct(&1, module))
+    end)
  end

-  def deserialize(model, field, :struct, mod, options) do
+  def deserialize(model, field, :struct, module) do
    model
-    |> Map.update!(field, &(Poison.Decode.decode(&1, Keyword.merge(options, [as: struct(mod)]))))
+    |> Map.update!(field, fn
+      nil ->
+        nil
+
+      value ->
+        to_struct(value, module)
+    end)
  end

-  def deserialize(model, field, :map, mod, options) do
+  def deserialize(model, field, :map, module) do
    maybe_transform_map = fn
      nil ->
        nil

      existing_value ->
        Map.new(existing_value, fn
-          {key, val} ->
-            {key, Poison.Decode.decode(val, Keyword.merge(options, as: struct(mod)))}
+          {key, value} ->
+            {key, to_struct(value, module)}
        end)
    end

    Map.update!(model, field, maybe_transform_map)
  end

-  def deserialize(model, field, :date, _, _options) do
+  def deserialize(model, field, :date, _) do
    value = Map.get(model, field)
+
+    case is_binary(value) do
+      true ->
+        case Date.from_iso8601(value) do
+          {:ok, date} -> Map.put(model, field, date)
+          _ -> model
+        end
+
+      false ->
+        model
+    end
+  end
+
+  def deserialize(model, field, :datetime, _) do
+    value = Map.get(model, field)
+
    case is_binary(value) do
      true ->
        case DateTime.from_iso8601(value) do
@ -48,4 +92,23 @@ defmodule OpenapiPetstore.Deserializer do
        model
    end
  end
+
+  defp to_struct(map_or_list, module)
+  defp to_struct(nil, _), do: nil
+
+  defp to_struct(list, module) when is_list(list) and is_atom(module) do
+    Enum.map(list, &to_struct(&1, module))
+  end
+
+  defp to_struct(map, module) when is_map(map) and is_atom(module) do
+    model = struct(module)
+
+    model
+    |> Map.keys()
+    |> List.delete(:__struct__)
+    |> Enum.reduce(model, fn field, acc ->
+      Map.replace(acc, field, Map.get(map, Atom.to_string(field)))
+    end)
+    |> module.decode()
+  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/_foo_get_default_response.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/_foo_get_default_response.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.FooGetDefaultResponse do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :string
  ]
@ -14,13 +14,12 @@ defmodule OpenapiPetstore.Model.FooGetDefaultResponse do
  @type t :: %__MODULE__{
    :string => OpenapiPetstore.Model.Foo.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.FooGetDefaultResponse do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:string, :struct, OpenapiPetstore.Model.Foo, options)
+     |> Deserializer.deserialize(:string, :struct, OpenapiPetstore.Model.Foo)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/_special_model_name_.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/_special_model_name_.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.SpecialModelName do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :"$special[property.name]"
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.SpecialModelName do
  @type t :: %__MODULE__{
    :"$special[property.name]" => integer() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.SpecialModelName do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/additional_properties_class.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/additional_properties_class.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.AdditionalPropertiesClass do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :map_property,
    :map_of_map_property
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.AdditionalPropertiesClass do
    :map_property => %{optional(String.t) => String.t} | nil,
    :map_of_map_property => %{optional(String.t) => %{optional(String.t) => String.t}} | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.AdditionalPropertiesClass do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/all_of_with_single_ref.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/all_of_with_single_ref.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.AllOfWithSingleRef do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :username,
    :SingleRefType
@ -16,13 +16,12 @@ defmodule OpenapiPetstore.Model.AllOfWithSingleRef do
    :username => String.t | nil,
    :SingleRefType => OpenapiPetstore.Model.SingleRefType.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.AllOfWithSingleRef do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:SingleRefType, :struct, OpenapiPetstore.Model.SingleRefType, options)
+     |> Deserializer.deserialize(:SingleRefType, :struct, OpenapiPetstore.Model.SingleRefType)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/animal.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/animal.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Animal do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :className,
    :color
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.Animal do
    :className => String.t,
    :color => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Animal do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/api_response.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/api_response.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ApiResponse do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :code,
    :type,
@ -18,10 +18,8 @@ defmodule OpenapiPetstore.Model.ApiResponse do
    :type => String.t | nil,
    :message => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ApiResponse do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/array_of_array_of_number_only.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/array_of_array_of_number_only.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ArrayOfArrayOfNumberOnly do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :ArrayArrayNumber
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.ArrayOfArrayOfNumberOnly do
  @type t :: %__MODULE__{
    :ArrayArrayNumber => [[float()]] | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ArrayOfArrayOfNumberOnly do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/array_of_number_only.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/array_of_number_only.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ArrayOfNumberOnly do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :ArrayNumber
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.ArrayOfNumberOnly do
  @type t :: %__MODULE__{
    :ArrayNumber => [float()] | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ArrayOfNumberOnly do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/array_test.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/array_test.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ArrayTest do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :array_of_string,
    :array_array_of_integer,
@ -18,10 +18,8 @@ defmodule OpenapiPetstore.Model.ArrayTest do
    :array_array_of_integer => [[integer()]] | nil,
    :array_array_of_model => [[OpenapiPetstore.Model.ReadOnlyFirst.t]] | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ArrayTest do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/capitalization.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/capitalization.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Capitalization do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :smallCamel,
    :CapitalCamel,
@ -24,10 +24,8 @@ defmodule OpenapiPetstore.Model.Capitalization do
    :SCA_ETH_Flow_Points => String.t | nil,
    :ATT_NAME => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Capitalization do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/cat.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/cat.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Cat do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :className,
    :color,
@ -18,10 +18,8 @@ defmodule OpenapiPetstore.Model.Cat do
    :color => String.t | nil,
    :declawed => boolean() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Cat do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/category.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/category.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Category do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :id,
    :name
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.Category do
    :id => integer() | nil,
    :name => String.t
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Category do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/class_model.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/class_model.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ClassModel do
  Model for testing model with \"_class\" property
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :_class
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.ClassModel do
  @type t :: %__MODULE__{
    :_class => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ClassModel do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/client.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/client.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Client do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :client
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.Client do
  @type t :: %__MODULE__{
    :client => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Client do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/deprecated_object.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/deprecated_object.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.DeprecatedObject do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :name
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.DeprecatedObject do
  @type t :: %__MODULE__{
    :name => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.DeprecatedObject do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/dog.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/dog.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Dog do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :className,
    :color,
@ -18,10 +18,8 @@ defmodule OpenapiPetstore.Model.Dog do
    :color => String.t | nil,
    :breed => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Dog do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/enum_arrays.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/enum_arrays.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.EnumArrays do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :just_symbol,
    :array_enum
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.EnumArrays do
    :just_symbol => String.t | nil,
    :array_enum => [String.t] | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.EnumArrays do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/enum_class.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/enum_class.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.EnumClass do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.EnumClass do
  @type t :: %__MODULE__{
    
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.EnumClass do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/enum_test.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/enum_test.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.EnumTest do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :enum_string,
    :enum_string_required,
@ -28,16 +28,15 @@ defmodule OpenapiPetstore.Model.EnumTest do
    :outerEnumDefaultValue => OpenapiPetstore.Model.OuterEnumDefaultValue.t | nil,
    :outerEnumIntegerDefaultValue => OpenapiPetstore.Model.OuterEnumIntegerDefaultValue.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.EnumTest do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:outerEnum, :struct, OpenapiPetstore.Model.OuterEnum, options)
-    |> deserialize(:outerEnumInteger, :struct, OpenapiPetstore.Model.OuterEnumInteger, options)
-    |> deserialize(:outerEnumDefaultValue, :struct, OpenapiPetstore.Model.OuterEnumDefaultValue, options)
-    |> deserialize(:outerEnumIntegerDefaultValue, :struct, OpenapiPetstore.Model.OuterEnumIntegerDefaultValue, options)
+     |> Deserializer.deserialize(:outerEnum, :struct, OpenapiPetstore.Model.OuterEnum)
+     |> Deserializer.deserialize(:outerEnumInteger, :struct, OpenapiPetstore.Model.OuterEnumInteger)
+     |> Deserializer.deserialize(:outerEnumDefaultValue, :struct, OpenapiPetstore.Model.OuterEnumDefaultValue)
+     |> Deserializer.deserialize(:outerEnumIntegerDefaultValue, :struct, OpenapiPetstore.Model.OuterEnumIntegerDefaultValue)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/fake_big_decimal_map_200_response.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/fake_big_decimal_map_200_response.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.FakeBigDecimalMap200Response do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :someId,
    :someMap
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.FakeBigDecimalMap200Response do
    :someId => float() | nil,
    :someMap => %{optional(String.t) => float()} | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.FakeBigDecimalMap200Response do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/file.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/file.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.File do
  Must be named `File` for test.
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :sourceURI
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.File do
  @type t :: %__MODULE__{
    :sourceURI => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.File do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/file_schema_test_class.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/file_schema_test_class.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.FileSchemaTestClass do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :file,
    :files
@ -16,14 +16,13 @@ defmodule OpenapiPetstore.Model.FileSchemaTestClass do
    :file => OpenapiPetstore.Model.File.t | nil,
    :files => [OpenapiPetstore.Model.File.t] | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.FileSchemaTestClass do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:file, :struct, OpenapiPetstore.Model.File, options)
-    |> deserialize(:files, :list, OpenapiPetstore.Model.File, options)
+     |> Deserializer.deserialize(:file, :struct, OpenapiPetstore.Model.File)
+     |> Deserializer.deserialize(:files, :list, OpenapiPetstore.Model.File)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/foo.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/foo.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Foo do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :bar
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.Foo do
  @type t :: %__MODULE__{
    :bar => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Foo do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/format_test.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/format_test.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.FormatTest do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :integer,
    :int32,
@ -44,13 +44,13 @@ defmodule OpenapiPetstore.Model.FormatTest do
    :pattern_with_digits => String.t | nil,
    :pattern_with_digits_and_delimiter => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.FormatTest do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:date, :date, nil, options)
+     |> Deserializer.deserialize(:date, :date, nil)
+     |> Deserializer.deserialize(:dateTime, :datetime, nil)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/has_only_read_only.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/has_only_read_only.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.HasOnlyReadOnly do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :bar,
    :foo
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.HasOnlyReadOnly do
    :bar => String.t | nil,
    :foo => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.HasOnlyReadOnly do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/health_check_result.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/health_check_result.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.HealthCheckResult do
  Just a string to inform instance is up and running. Make it nullable in hope to get it as pointer in generated model.
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :NullableMessage
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.HealthCheckResult do
  @type t :: %__MODULE__{
    :NullableMessage => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.HealthCheckResult do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/list.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/list.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.List do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :"123-list"
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.List do
  @type t :: %__MODULE__{
    :"123-list" => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.List do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/map_test.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/map_test.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.MapTest do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :map_map_of_string,
    :map_of_enum_string,
@ -20,10 +20,8 @@ defmodule OpenapiPetstore.Model.MapTest do
    :direct_map => %{optional(String.t) => boolean()} | nil,
    :indirect_map => %{optional(String.t) => boolean()} | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.MapTest do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/mixed_properties_and_additional_properties_class.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/mixed_properties_and_additional_properties_class.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.MixedPropertiesAndAdditionalPropertiesClass do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :uuid,
    :dateTime,
@ -18,13 +18,13 @@ defmodule OpenapiPetstore.Model.MixedPropertiesAndAdditionalPropertiesClass do
    :dateTime => DateTime.t | nil,
    :map => %{optional(String.t) => OpenapiPetstore.Model.Animal.t} | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.MixedPropertiesAndAdditionalPropertiesClass do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:map, :map, OpenapiPetstore.Model.Animal, options)
+     |> Deserializer.deserialize(:dateTime, :datetime, nil)
+     |> Deserializer.deserialize(:map, :map, OpenapiPetstore.Model.Animal)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/model_200_response.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/model_200_response.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Model200Response do
  Model for testing model name starting with number
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :name,
    :class
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.Model200Response do
    :name => integer() | nil,
    :class => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Model200Response do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/name.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/name.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Name do
  Model for testing model name same as property name
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :name,
    :snake_case,
@ -20,10 +20,8 @@ defmodule OpenapiPetstore.Model.Name do
    :property => String.t | nil,
    :"123Number" => integer() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Name do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/nullable_class.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/nullable_class.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.NullableClass do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :integer_prop,
    :number_prop,
@ -36,13 +36,13 @@ defmodule OpenapiPetstore.Model.NullableClass do
    :object_and_items_nullable_prop => %{optional(String.t) => map()} | nil,
    :object_items_nullable => %{optional(String.t) => map()} | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.NullableClass do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:date_prop, :date, nil, options)
+     |> Deserializer.deserialize(:date_prop, :date, nil)
+     |> Deserializer.deserialize(:datetime_prop, :datetime, nil)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/number_only.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/number_only.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.NumberOnly do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :JustNumber
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.NumberOnly do
  @type t :: %__MODULE__{
    :JustNumber => float() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.NumberOnly do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/object_with_deprecated_fields.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/object_with_deprecated_fields.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ObjectWithDeprecatedFields do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :uuid,
    :id,
@ -18,15 +18,14 @@ defmodule OpenapiPetstore.Model.ObjectWithDeprecatedFields do
    :uuid => String.t | nil,
    :id => float() | nil,
    :deprecatedRef => OpenapiPetstore.Model.DeprecatedObject.t | nil,
-    :bars => [OpenapiPetstore.Model.String.t] | nil
+    :bars => [String.t] | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ObjectWithDeprecatedFields do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:deprecatedRef, :struct, OpenapiPetstore.Model.DeprecatedObject, options)
+     |> Deserializer.deserialize(:deprecatedRef, :struct, OpenapiPetstore.Model.DeprecatedObject)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/order.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/order.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Order do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :id,
    :petId,
@ -24,11 +24,12 @@ defmodule OpenapiPetstore.Model.Order do
    :status => String.t | nil,
    :complete => boolean() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Order do
-  def decode(value, _options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
+     |> Deserializer.deserialize(:shipDate, :datetime, nil)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_composite.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_composite.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.OuterComposite do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :my_number,
    :my_string,
@ -18,10 +18,8 @@ defmodule OpenapiPetstore.Model.OuterComposite do
    :my_string => String.t | nil,
    :my_boolean => boolean() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.OuterComposite do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.OuterEnum do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.OuterEnum do
  @type t :: %__MODULE__{
    
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.OuterEnum do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum_default_value.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum_default_value.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.OuterEnumDefaultValue do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.OuterEnumDefaultValue do
  @type t :: %__MODULE__{
    
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.OuterEnumDefaultValue do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum_integer.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum_integer.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.OuterEnumInteger do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.OuterEnumInteger do
  @type t :: %__MODULE__{
    
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.OuterEnumInteger do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum_integer_default_value.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_enum_integer_default_value.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.OuterEnumIntegerDefaultValue do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.OuterEnumIntegerDefaultValue do
  @type t :: %__MODULE__{
    
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.OuterEnumIntegerDefaultValue do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_object_with_enum_property.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/outer_object_with_enum_property.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.OuterObjectWithEnumProperty do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :value
  ]
@ -14,13 +14,12 @@ defmodule OpenapiPetstore.Model.OuterObjectWithEnumProperty do
  @type t :: %__MODULE__{
    :value => OpenapiPetstore.Model.OuterEnumInteger.t
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.OuterObjectWithEnumProperty do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:value, :struct, OpenapiPetstore.Model.OuterEnumInteger, options)
+     |> Deserializer.deserialize(:value, :struct, OpenapiPetstore.Model.OuterEnumInteger)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/pet.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/pet.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Pet do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :id,
    :category,
@ -24,14 +24,13 @@ defmodule OpenapiPetstore.Model.Pet do
    :tags => [OpenapiPetstore.Model.Tag.t] | nil,
    :status => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Pet do
-  import OpenapiPetstore.Deserializer
-  def decode(value, options) do
+  alias OpenapiPetstore.Deserializer
+
+  def decode(value) do
    value
-    |> deserialize(:category, :struct, OpenapiPetstore.Model.Category, options)
-    |> deserialize(:tags, :list, OpenapiPetstore.Model.Tag, options)
+     |> Deserializer.deserialize(:category, :struct, OpenapiPetstore.Model.Category)
+     |> Deserializer.deserialize(:tags, :list, OpenapiPetstore.Model.Tag)
  end
 end

--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/read_only_first.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/read_only_first.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.ReadOnlyFirst do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :bar,
    :baz
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.ReadOnlyFirst do
    :bar => String.t | nil,
    :baz => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.ReadOnlyFirst do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/return.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/return.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Return do
  Model for testing reserved words
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :return
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.Return do
  @type t :: %__MODULE__{
    :return => integer() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Return do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/single_ref_type.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/single_ref_type.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.SingleRefType do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    
  ]
@ -14,10 +14,8 @@ defmodule OpenapiPetstore.Model.SingleRefType do
  @type t :: %__MODULE__{
    
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.SingleRefType do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/tag.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/tag.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.Tag do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :id,
    :name
@ -16,10 +16,8 @@ defmodule OpenapiPetstore.Model.Tag do
    :id => integer() | nil,
    :name => String.t | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.Tag do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/model/user.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/model/user.ex
@ -6,7 +6,7 @@ defmodule OpenapiPetstore.Model.User do
  
  """

-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
  defstruct [
    :id,
    :username,
@ -28,10 +28,8 @@ defmodule OpenapiPetstore.Model.User do
    :phone => String.t | nil,
    :userStatus => integer() | nil
  }
-end

-defimpl Poison.Decoder, for: OpenapiPetstore.Model.User do
-  def decode(value, _options) do
+  def decode(value) do
    value
  end
 end
--- a/samples/client/petstore/elixir/lib/openapi_petstore/request_builder.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/request_builder.ex
@ -96,7 +96,7 @@ defmodule OpenapiPetstore.RequestBuilder do
      Tesla.Multipart.add_field(
        multipart,
        key,
-        Poison.encode!(value),
+        Jason.encode!(value),
        headers: [{:"Content-Type", "application/json"}]
      )
    end)
@ -148,8 +148,8 @@ defmodule OpenapiPetstore.RequestBuilder do
    Map.put_new(request, :body, "")
  end

-  @type status_code :: 100..599
-  @type response_mapping :: [{status_code, struct() | false}]
+  @type status_code :: :default | 100..599
+  @type response_mapping :: [{status_code, false | %{} | module()}]

  @doc """
  Evaluate the response from a Tesla request.
@ -187,5 +187,11 @@ defmodule OpenapiPetstore.RequestBuilder do

  defp decode(%Tesla.Env{} = env, false), do: {:ok, env}

-  defp decode(%Tesla.Env{body: body}, struct), do: Poison.decode(body, as: struct)
+  defp decode(%Tesla.Env{body: body}, %{}) do
+    OpenapiPetstore.Deserializer.jason_decode(body)
+  end
+
+  defp decode(%Tesla.Env{body: body}, module) do
+    OpenapiPetstore.Deserializer.jason_decode(body, module)
+  end
 end
--- a/samples/client/petstore/elixir/mix.exs
+++ b/samples/client/petstore/elixir/mix.exs
@ -9,7 +9,9 @@ defmodule OpenapiPetstore.Mixfile do
      build_embedded: Mix.env() == :prod,
      start_permanent: Mix.env() == :prod,
      package: package(),
-      description: "This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \&quot; \\",
+      description: """
+      This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \&quot; \\
+      """,
      deps: deps()
    ]
  end
@ -33,9 +35,10 @@ defmodule OpenapiPetstore.Mixfile do
  # Type "mix help deps" for more examples and options
  defp deps do
    [
-      {:tesla, "~> 1.4"},
-      {:poison, "~> 3.0"},
-      {:ex_doc, "~> 0.28", only: :dev, runtime: false}
+      {:tesla, "~> 1.7"},
+      {:jason, "~> 1.4"},
+      {:ex_doc, "~> 0.30", only: :dev, runtime: false},
+      {:dialyxir, "~> 1.3", only: [:dev, :test], runtime: false}
    ]
  end

--- a/samples/client/petstore/elixir/test/deserializer_test.exs
+++ b/samples/client/petstore/elixir/test/deserializer_test.exs
@ -0,0 +1,49 @@
+defmodule DeserializerTest do
+  use ExUnit.Case, async: true
+  alias OpenapiPetstore.Deserializer
+  alias OpenapiPetstore.Model.{Category, Pet, Tag}
+
+  @valid_json """
+  {
+    "id": 14,
+    "category": {
+      "id": 75,
+      "name": "sea dragons"
+    },
+    "name": "Nagga",
+    "photoUrls": [
+      "https://example.com/nagga1.jpg",
+      "https://example.com/nagga2.jpg"
+    ],
+    "tags": [
+      {
+        "id": 99,
+        "name": "dragon"
+      },
+      {
+        "id": 23,
+        "name": "sea"
+      }
+    ],
+    "status": "foo"
+  }
+  """
+
+  test "jason_decode/2 with valid JSON" do
+    assert Deserializer.jason_decode(@valid_json, Pet) ==
+             {:ok,
+              %Pet{
+                id: 14,
+                category: %Category{id: 75, name: "sea dragons"},
+                name: "Nagga",
+                photoUrls: ["https://example.com/nagga1.jpg", "https://example.com/nagga2.jpg"],
+                tags: [%Tag{id: 99, name: "dragon"}, %Tag{id: 23, name: "sea"}],
+                status: "foo"
+              }}
+  end
+
+  test "jason_decode/2 with invalid JSON" do
+    assert Deserializer.jason_decode(~s/{: 1}/, Pet) ==
+             {:error, %Jason.DecodeError{data: "{: 1}", position: 1, token: nil}}
+  end
+end
--- a/samples/client/petstore/elixir/test/format_test.exs
+++ b/samples/client/petstore/elixir/test/format_test.exs
@ -0,0 +1,84 @@
+defmodule FormatTest do
+  use ExUnit.Case, async: true
+  alias OpenapiPetstore.Model.FormatTest
+
+  test "decode all properties (not nil)" do
+    assert %FormatTest{
+             integer: 1,
+             int32: 2,
+             int64: 3,
+             number: 4.1,
+             float: 5.2,
+             double: 6.3,
+             decimal: "7.4",
+             string: "Hello world!",
+             byte: "U3dhZ2dlciByb2Nrcw==",
+             binary: <<1, 2, 3>>,
+             date: "2013-10-20",
+             dateTime: "2013-10-20T19:20:30+01:00",
+             uuid: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
+             password: "green?horse",
+             pattern_with_digits: "1234567890",
+             pattern_with_digits_and_delimiter: "Image_01"
+           }
+           |> FormatTest.decode() ==
+             %FormatTest{
+               integer: 1,
+               int32: 2,
+               int64: 3,
+               number: 4.1,
+               float: 5.2,
+               double: 6.3,
+               decimal: "7.4",
+               string: "Hello world!",
+               byte: "U3dhZ2dlciByb2Nrcw==",
+               binary: <<1, 2, 3>>,
+               date: ~D[2013-10-20],
+               dateTime: ~U[2013-10-20T18:20:30Z],
+               uuid: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
+               password: "green?horse",
+               pattern_with_digits: "1234567890",
+               pattern_with_digits_and_delimiter: "Image_01"
+             }
+  end
+
+  test "decode all properties (some are nil)" do
+    assert %FormatTest{
+             integer: nil,
+             int32: nil,
+             int64: nil,
+             number: 4.1,
+             float: nil,
+             double: nil,
+             decimal: nil,
+             string: nil,
+             byte: "U3dhZ2dlciByb2Nrcw==",
+             binary: nil,
+             date: "2013-10-20",
+             dateTime: nil,
+             uuid: nil,
+             password: "green?horse",
+             pattern_with_digits: nil,
+             pattern_with_digits_and_delimiter: nil
+           }
+           |> FormatTest.decode() ==
+             %FormatTest{
+               integer: nil,
+               int32: nil,
+               int64: nil,
+               number: 4.1,
+               float: nil,
+               double: nil,
+               decimal: nil,
+               string: nil,
+               byte: "U3dhZ2dlciByb2Nrcw==",
+               binary: nil,
+               date: ~D[2013-10-20],
+               dateTime: nil,
+               uuid: nil,
+               password: "green?horse",
+               pattern_with_digits: nil,
+               pattern_with_digits_and_delimiter: nil
+             }
+  end
+end
--- a/samples/client/petstore/elixir/test/mixed_properties_and_additional_properties_class_test.exs
+++ b/samples/client/petstore/elixir/test/mixed_properties_and_additional_properties_class_test.exs
@ -0,0 +1,46 @@
+defmodule MixedPropertiesAndAdditionalPropertiesClass do
+  use ExUnit.Case, async: true
+  alias OpenapiPetstore.Model.MixedPropertiesAndAdditionalPropertiesClass, as: Model
+  alias OpenapiPetstore.Model.Animal
+
+  test "decode all properties (not nil)" do
+    assert %Model{
+             uuid: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
+             dateTime: "2013-10-20T19:20:30+01:00",
+             map: %{
+               "doggie" => %{"className" => "DOG", "color" => "yellow", "breed" => "Shiba Inu"},
+               "meow" => %{"className" => "CAT", "color" => "white", "declawed" => false}
+             }
+           }
+           |> Model.decode() ==
+             %Model{
+               uuid: "3fa85f64-5717-4562-b3fc-2c963f66afa6",
+               dateTime: ~U[2013-10-20T18:20:30Z],
+               map: %{
+                 # TODO values should be Dog and Cat structs instead of an Animal
+                 "doggie" => %Animal{
+                   className: "DOG",
+                   color: "yellow"
+                 },
+                 "meow" => %Animal{
+                   className: "CAT",
+                   color: "white"
+                 }
+               }
+             }
+  end
+
+  test "decode all properties (nil)" do
+    assert %Model{
+             uuid: nil,
+             dateTime: nil,
+             map: nil
+           }
+           |> Model.decode() ==
+             %Model{
+               uuid: nil,
+               dateTime: nil,
+               map: nil
+             }
+  end
+end
--- a/samples/client/petstore/elixir/test/pet_test.exs
+++ b/samples/client/petstore/elixir/test/pet_test.exs
@ -1,60 +1,66 @@
 defmodule PetTest do
-    use ExUnit.Case
-    alias OpenapiPetstore.Connection
-    alias OpenapiPetstore.Api.Pet, as: PetApi
-    alias OpenapiPetstore.Model.Pet
-    alias OpenapiPetstore.Model.Category
-    alias OpenapiPetstore.Model.Tag
+  use ExUnit.Case, async: true
+  alias OpenapiPetstore.Connection
+  alias OpenapiPetstore.Api.Pet, as: PetApi
+  alias OpenapiPetstore.Model.Pet
+  alias OpenapiPetstore.Model.Category
+  alias OpenapiPetstore.Model.Tag

-    test "add and delete a pet" do
-        petId = 10007
-        pet = %Pet{
-            :id => petId,
-            :name => "elixir client test",
-            :photoUrls => ["http://test_elixir_unit_test.com"],
-            :category => %Category{:id => petId, :name=> "test elixir category"},
-            :tags => [%Tag{:id => petId, :name => "test elixir tag"}],
-        }
-        {:ok, response} = PetApi.add_pet(Connection.new, pet)
-        assert response.status == 200
+  setup do
+    %{connection: Connection.new()}
+  end

-        {:ok, pet} = PetApi.get_pet_by_id(Connection.new, petId)
-        assert pet.id == petId
-        assert pet.name == "elixir client test"
-        assert List.first(pet.photoUrls) == "http://test_elixir_unit_test.com"
-        assert pet.category.id == petId
-        assert pet.category.name == "test elixir category"
-        assert List.first(pet.tags) == %Tag{:id => petId, :name => "test elixir tag"}
+  test "add and delete a pet", %{connection: connection} do
+    petId = 10007

-        {:ok, response} = PetApi.delete_pet(Connection.new, petId)
-        assert response.status == 200
-        {:ok, response} = PetApi.get_pet_by_id(Connection.new, petId)
-        assert response.status == 404
-    end
+    pet = %Pet{
+      :id => petId,
+      :name => "elixir client test",
+      :photoUrls => ["http://test_elixir_unit_test.com"],
+      :category => %Category{:id => petId, :name => "test elixir category"},
+      :tags => [%Tag{:id => petId, :name => "test elixir tag"}]
+    }

-    test "update a pet" do
-        petId = 10007
-        pet = %Pet{
-            :id => petId,
-            :name => "elixir client updatePet",
-            :status => "pending",
-            :photoUrls => ["http://test_elixir_unit_test.com"]
-        }
-        {:ok, response} = PetApi.update_pet(Connection.new, pet)
-        assert response.status == 200
+    {:ok, %Tesla.Env{} = response} = PetApi.add_pet(connection, pet)
+    assert response.status == 200

-        {:ok, pet} = PetApi.get_pet_by_id(Connection.new, petId)
-        assert pet.id == petId
-        assert pet.name == "elixir client updatePet"
-        assert pet.status == "pending"
-    end
+    {:ok, pet} = PetApi.get_pet_by_id(connection, petId)
+    assert pet.id == petId
+    assert pet.name == "elixir client test"
+    assert pet.photoUrls == ["http://test_elixir_unit_test.com"]
+    assert pet.category == %Category{id: petId, name: "test elixir category"}
+    assert pet.tags == [%Tag{:id => petId, :name => "test elixir tag"}]

-    test "find pet by status" do
-        {:ok, listPets} = PetApi.find_pets_by_status(Connection.new, "available")
-        assert List.first(listPets) != nil
+    {:ok, response} = PetApi.delete_pet(connection, petId)
+    assert response.status == 200
+    {:ok, response} = PetApi.get_pet_by_id(connection, petId)
+    assert response.status == 404
+  end

-        {:ok, listPets} = PetApi.find_pets_by_status(Connection.new, "unknown_and_incorrect_status")
-        assert List.first(listPets) == nil
-    end
+  test "update a pet", %{connection: connection} do
+    petId = 10007

+    pet = %Pet{
+      :id => petId,
+      :name => "elixir client updatePet",
+      :status => "pending",
+      :photoUrls => ["http://test_elixir_unit_test.com"]
+    }
+
+    {:ok, response} = PetApi.update_pet(connection, pet)
+    assert response.status == 200
+
+    {:ok, pet} = PetApi.get_pet_by_id(connection, petId)
+    assert pet.id == petId
+    assert pet.name == "elixir client updatePet"
+    assert pet.status == "pending"
+  end
+
+  test "find pet by status", %{connection: connection} do
+    {:ok, listPets} = PetApi.find_pets_by_status(connection, "available")
+    assert List.first(listPets) != nil
+
+    {:ok, listPets} = PetApi.find_pets_by_status(connection, "unknown_and_incorrect_status")
+    assert List.first(listPets) == nil
+  end
 end
--- a/samples/client/petstore/elixir/test/store_test.exs
+++ b/samples/client/petstore/elixir/test/store_test.exs
@ -0,0 +1,17 @@
+defmodule StoreTest do
+  use ExUnit.Case, async: true
+  alias OpenapiPetstore.Connection
+  alias OpenapiPetstore.Api.Store, as: StoreApi
+
+  setup do
+    %{connection: Connection.new()}
+  end
+
+  test "fetch inventory", %{connection: connection} do
+    {:ok, inventory} = StoreApi.get_inventory(connection)
+
+    assert is_map(inventory)
+    assert Enum.all?(Map.keys(inventory), &is_binary/1)
+    assert Enum.all?(Map.values(inventory), &is_integer/1)
+  end
+end