[Go-server] - Support for Enums in the Path and Query (#16781)

* Add support for Enums to be part of the Path and Query
Supports optional Query Enums and Lists of Enums as well
Add an example endpoint that covers the added scenarios
Added an import mapping for the GoServerCodegen for "fmt"
    when a model is an enum.
Expanded the Enum Model for the Go Server to have validation.
    Copied this logic from the Go Client Enum Model.

* Fix identation of examples

* Pre-allocate the capacity of the slice of Enums to be
the correct size.

* Formatting and updated examples

* Empty-Commit

* Switch to using a map to store the valid enum values

* Fixed pointer derefs missed from previous change in PR

* More fixing of pointer to not pointer

* Create a map for validation and a list of enums for messaging

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoServerCodegen.java

@@ -301,6 +301,7 @@ public class GoServerCodegen extends AbstractGoCodegen {
 
             CodegenModel model = m.getModel();
             if (model.isEnum) {
+                imports.add(createMapping("import", "fmt"));
                 continue;
             }
 

modules/openapi-generator/src/main/resources/go-server/controller-api.mustache

@@ -173,7 +173,16 @@ func (c *{{classname}}Controller) {{nickname}}(w http.ResponseWriter, r *http.Re
 	{{^isDouble}}
 	{{^isLong}}
 	{{^isInteger}}
+	{{^isEnumOrRef}}
 	{{paramName}}Param := {{#routers}}{{#mux}}params["{{baseName}}"]{{/mux}}{{#chi}}chi.URLParam(r, "{{baseName}}"){{/chi}}{{/routers}}
+	{{/isEnumOrRef}}
+	{{#isEnumOrRef}}
+	{{paramName}}Param, err := New{{dataType}}FromValue({{#routers}}{{#mux}}params["{{baseName}}"]{{/mux}}{{#chi}}chi.URLParam(r, "{{baseName}}"){{/chi}}{{/routers}})
+	if err != nil {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	{{/isEnumOrRef}}
 	{{/isInteger}}
 	{{/isLong}}
 	{{/isDouble}}
@@ -329,7 +338,27 @@ func (c *{{classname}}Controller) {{nickname}}(w http.ResponseWriter, r *http.Re
 	{{^items.isDouble}}
 	{{^items.isLong}}
 	{{^items.isInteger}}
-	{{paramName}}Param := strings.Split(query.Get("{{baseName}}"), ",")
+	{{^items.isEnumRef}}
+	var {{paramName}}Param []string
+	if query.Has("{{baseName}}") {
+		{{paramName}}Param = strings.Split(query.Get("{{baseName}}"), ",")
+	}
+	{{/items.isEnumRef}}
+	{{#items.isEnumRef}}
+	var {{paramName}}Param []{{items.dataType}}
+	if query.Has("{{baseName}}") {
+		paramSplits := strings.Split(query.Get("{{baseName}}"), ",")
+		{{paramName}}Param = make([]{{items.dataType}}, 0, len(paramSplits))
+		for _, param := range paramSplits {
+			paramEnum, err := New{{items.dataType}}FromValue(param)
+			if err != nil {
+				c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+				return
+			}
+			{{paramName}}Param = append({{paramName}}Param, paramEnum)
+		}
+	}
+	{{/items.isEnumRef}}
 	{{/items.isInteger}}
 	{{/items.isLong}}
 	{{/items.isDouble}}
@@ -346,11 +375,42 @@ func (c *{{classname}}Controller) {{nickname}}(w http.ResponseWriter, r *http.Re
 	{{#defaultValue}}
 	{{paramName}}Param := "{{defaultValue}}"
 	if query.Has("{{baseName}}") {
-		{{paramName}}Param = query.Get("{{baseName}}")
+		{{paramName}}Param = {{^isString}}{{dataType}}( {{/isString}}query.Get("{{baseName}}"){{^isString}} ){{/isString}}
 	}
 	{{/defaultValue}}
 	{{^defaultValue}}
+	{{^required}}
+	var {{paramName}}Param {{dataType}}
+	if query.Has("{{baseName}}") {
+		{{^isEnumOrRef}}
+		{{paramName}}Param = query.Get("{{baseName}}")
+		{{/isEnumOrRef}}
+		{{#isEnumOrRef}}
+		var err error
+		{{paramName}}Param, err = New{{dataType}}FromValue(query.Get("{{baseName}}"))
+		if err != nil {
+			c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+			return
+		}
+		{{/isEnumOrRef}}
+	}
+	{{/required}}
+	{{#required}}
+	{{^isEnumOrRef}}
 	{{paramName}}Param := query.Get("{{baseName}}")
+	{{/isEnumOrRef}}
+	{{#isEnumOrRef}}
+	if !query.Has("{{baseName}}"){
+		c.errorHandler(w, r, &RequiredError{"{{baseName}}"}, nil)
+		return
+	}
+	{{paramName}}Param, err := New{{dataType}}FromValue(query.Get("{{baseName}}"))
+	if err != nil {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	{{/isEnumOrRef}}
+	{{/required}}
 	{{/defaultValue}}
 	{{/isArray}}
 	{{/isBoolean}}

modules/openapi-generator/src/main/resources/go-server/model.mustache

@@ -17,7 +17,44 @@ const (
 	{{#enumClassPrefix}}{{{classname.toUpperCase}}}_{{/enumClassPrefix}}{{name}} {{{classname}}} = {{{value}}}
 	{{/enumVars}}
 	{{/allowableValues}}
-){{/isEnum}}{{^isEnum}}{{#description}}
+)
+
+// Allowed{{{classname}}}EnumValues is all the allowed values of {{{classname}}} enum
+var Allowed{{{classname}}}EnumValues = []{{{classname}}}{
+	{{#allowableValues}}
+	{{#enumVars}}
+	{{{value}}},
+	{{/enumVars}}
+	{{/allowableValues}}
+}
+
+// valid{{{classname}}}EnumValue provides a map of {{classname}}s for fast verification of use input
+var valid{{{classname}}}EnumValues = map[{{{classname}}}]struct{}{
+	{{#allowableValues}}
+	{{#enumVars}}
+	{{{value}}}: {},
+	{{/enumVars}}
+	{{/allowableValues}}
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v {{{classname}}}) IsValid() bool {
+	_, ok := valid{{{classname}}}EnumValues[v]
+	return ok
+}
+
+// New{{{classname}}}FromValue returns a pointer to a valid {{{classname}}}
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func New{{{classname}}}FromValue(v {{{format}}}{{^format}}{{dataType}}{{/format}}) ({{{classname}}}, error) {
+	ev := {{{classname}}}(v)
+	if ev.IsValid() {
+		return ev, nil
+	} else {
+		return "", fmt.Errorf("invalid value '%v' for {{{classname}}}: valid values are %v", v, Allowed{{{classname}}}EnumValues)
+	}
+}
+
+{{/isEnum}}{{^isEnum}}{{#description}}
 // {{classname}} - {{{description}}}{{/description}}
 type {{classname}} struct {
 {{#parent}}

modules/openapi-generator/src/test/resources/3_0/go-server/petstore.yaml

@@ -157,6 +157,52 @@ paths:
         - petstore_auth:
             - 'read:pets'
       deprecated: true
+  '/pet/filterPets/{gender}':
+    get:
+      tags:
+        - pet
+      summary: Finds Pets
+      operationId: filterPetsByCategory
+      parameters:
+        - name: gender
+          in: path
+          required: true
+          schema:
+            $ref: '#/components/schemas/Gender'
+        - name: species
+          in: query
+          description: Species to filter by
+          required: true
+          style: form
+          explode: false
+          schema:
+            $ref: '#/components/schemas/Species'
+        - name: notSpecies
+          in: query
+          description: Species to omit from results
+          required: false
+          style: form
+          explode: false
+          schema:
+            type: array
+            items:
+              $ref: '#/components/schemas/Species'
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/xml:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Pet'
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Pet'
+        '400':
+          description: Invalid species value
   '/pet/{petId}':
     get:
       tags:
@@ -851,6 +897,20 @@ components:
             - sold
       xml:
         name: Pet
+    Species:
+      title: The species of a pet
+      type: string
+      enum:
+        - cat
+        - dog
+        - fish
+        - goat
+        - pig
+    Gender:
+      type: string
+      enum:
+        - male
+        - female
     ApiResponse:
       title: An uploaded response
       description: Describes the result of uploading an image resource

samples/openapi3/server/petstore/go/go-petstore/go/api_pet.go

@@ -144,7 +144,10 @@ func (c *PetAPIController) DeletePet(w http.ResponseWriter, r *http.Request) {
 // FindPetsByStatus - Finds Pets by status
 func (c *PetAPIController) FindPetsByStatus(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	statusParam := strings.Split(query.Get("status"), ",")
+	var statusParam []string
+	if query.Has("status") {
+		statusParam = strings.Split(query.Get("status"), ",")
+	}
 	result, err := c.service.FindPetsByStatus(r.Context(), statusParam)
 	// If an error occurred, encode the error with the status code
 	if err != nil {
@@ -159,7 +162,10 @@ func (c *PetAPIController) FindPetsByStatus(w http.ResponseWriter, r *http.Reque
 // Deprecated
 func (c *PetAPIController) FindPetsByTags(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	tagsParam := strings.Split(query.Get("tags"), ",")
+	var tagsParam []string
+	if query.Has("tags") {
+		tagsParam = strings.Split(query.Get("tags"), ",")
+	}
 	result, err := c.service.FindPetsByTags(r.Context(), tagsParam)
 	// If an error occurred, encode the error with the status code
 	if err != nil {

samples/server/petstore/go-api-server/.openapi-generator/FILES

@@ -16,10 +16,12 @@ go/logger.go
 go/model_an_object.go
 go/model_api_response.go
 go/model_category.go
+go/model_gender.go
 go/model_order.go
 go/model_order_info.go
 go/model_pet.go
 go/model_special_info.go
+go/model_species.go
 go/model_tag.go
 go/model_user.go
 go/routers.go

samples/server/petstore/go-api-server/api/openapi.yaml

@@ -158,6 +158,54 @@ paths:
       summary: Finds Pets by tags
       tags:
       - pet
+  /pet/filterPets/{gender}:
+    get:
+      operationId: filterPetsByCategory
+      parameters:
+      - explode: false
+        in: path
+        name: gender
+        required: true
+        schema:
+          $ref: '#/components/schemas/Gender'
+        style: simple
+      - description: Species to filter by
+        explode: false
+        in: query
+        name: species
+        required: true
+        schema:
+          $ref: '#/components/schemas/Species'
+        style: form
+      - description: Species to omit from results
+        explode: false
+        in: query
+        name: notSpecies
+        required: false
+        schema:
+          items:
+            $ref: '#/components/schemas/Species'
+          type: array
+        style: form
+      responses:
+        "200":
+          content:
+            application/xml:
+              schema:
+                items:
+                  $ref: '#/components/schemas/Pet'
+                type: array
+            application/json:
+              schema:
+                items:
+                  $ref: '#/components/schemas/Pet'
+                type: array
+          description: successful operation
+        "400":
+          description: Invalid species value
+      summary: Finds Pets
+      tags:
+      - pet
   /pet/{petId}:
     delete:
       description: ""
@@ -1020,6 +1068,20 @@ components:
       type: object
       xml:
         name: Pet
+    Species:
+      enum:
+      - cat
+      - dog
+      - fish
+      - goat
+      - pig
+      title: The species of a pet
+      type: string
+    Gender:
+      enum:
+      - male
+      - female
+      type: string
     ApiResponse:
       description: Describes the result of uploading an image resource
       example:

samples/server/petstore/go-api-server/go/api.go

@@ -23,6 +23,7 @@ import (
 type PetAPIRouter interface { 
 	AddPet(http.ResponseWriter, *http.Request)
 	DeletePet(http.ResponseWriter, *http.Request)
+	FilterPetsByCategory(http.ResponseWriter, *http.Request)
 	FindPetsByStatus(http.ResponseWriter, *http.Request)
 	// Deprecated
 	FindPetsByTags(http.ResponseWriter, *http.Request)
@@ -63,6 +64,7 @@ type UserAPIRouter interface {
 type PetAPIServicer interface { 
 	AddPet(context.Context, Pet) (ImplResponse, error)
 	DeletePet(context.Context, int64, string) (ImplResponse, error)
+	FilterPetsByCategory(context.Context, Gender, Species, []Species) (ImplResponse, error)
 	FindPetsByStatus(context.Context, []string) (ImplResponse, error)
 	// Deprecated
 	FindPetsByTags(context.Context, []string) (ImplResponse, error)

samples/server/petstore/go-api-server/go/api_pet.go

@@ -60,6 +60,11 @@ func (c *PetAPIController) Routes() Routes {
 			"/v2/pet/{petId}",
 			c.DeletePet,
 		},
+		"FilterPetsByCategory": Route{
+			strings.ToUpper("Get"),
+			"/v2/pet/filterPets/{gender}",
+			c.FilterPetsByCategory,
+		},
 		"FindPetsByStatus": Route{
 			strings.ToUpper("Get"),
 			"/v2/pet/findByStatus",
@@ -147,10 +152,54 @@ func (c *PetAPIController) DeletePet(w http.ResponseWriter, r *http.Request) {
 	EncodeJSONResponse(result.Body, &result.Code, result.Headers, w)
 }
 
+// FilterPetsByCategory - Finds Pets
+func (c *PetAPIController) FilterPetsByCategory(w http.ResponseWriter, r *http.Request) {
+	params := mux.Vars(r)
+	query := r.URL.Query()
+	genderParam, err := NewGenderFromValue(params["gender"])
+	if err != nil {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	if !query.Has("species"){
+		c.errorHandler(w, r, &RequiredError{"species"}, nil)
+		return
+	}
+	speciesParam, err := NewSpeciesFromValue(query.Get("species"))
+	if err != nil {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	var notSpeciesParam []Species
+	if query.Has("notSpecies") {
+		paramSplits := strings.Split(query.Get("notSpecies"), ",")
+		notSpeciesParam = make([]Species, 0, len(paramSplits))
+		for _, param := range paramSplits {
+			paramEnum, err := NewSpeciesFromValue(param)
+			if err != nil {
+				c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+				return
+			}
+			notSpeciesParam = append(notSpeciesParam, paramEnum)
+		}
+	}
+	result, err := c.service.FilterPetsByCategory(r.Context(), genderParam, speciesParam, notSpeciesParam)
+	// If an error occurred, encode the error with the status code
+	if err != nil {
+		c.errorHandler(w, r, err, &result)
+		return
+	}
+	// If no error, encode the body and the result code
+	EncodeJSONResponse(result.Body, &result.Code, result.Headers, w)
+}
+
 // FindPetsByStatus - Finds Pets by status
 func (c *PetAPIController) FindPetsByStatus(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	statusParam := strings.Split(query.Get("status"), ",")
+	var statusParam []string
+	if query.Has("status") {
+		statusParam = strings.Split(query.Get("status"), ",")
+	}
 	result, err := c.service.FindPetsByStatus(r.Context(), statusParam)
 	// If an error occurred, encode the error with the status code
 	if err != nil {
@@ -165,7 +214,10 @@ func (c *PetAPIController) FindPetsByStatus(w http.ResponseWriter, r *http.Reque
 // Deprecated
 func (c *PetAPIController) FindPetsByTags(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	tagsParam := strings.Split(query.Get("tags"), ",")
+	var tagsParam []string
+	if query.Has("tags") {
+		tagsParam = strings.Split(query.Get("tags"), ",")
+	}
 	result, err := c.service.FindPetsByTags(r.Context(), tagsParam)
 	// If an error occurred, encode the error with the status code
 	if err != nil {

samples/server/petstore/go-api-server/go/api_pet_service.go

@@ -52,6 +52,20 @@ func (s *PetAPIService) DeletePet(ctx context.Context, petId int64, apiKey strin
 	return Response(http.StatusNotImplemented, nil), errors.New("DeletePet method not implemented")
 }
 
+// FilterPetsByCategory - Finds Pets
+func (s *PetAPIService) FilterPetsByCategory(ctx context.Context, gender Gender, species Species, notSpecies []Species) (ImplResponse, error) {
+	// TODO - update FilterPetsByCategory with the required logic for this service method.
+	// Add api_pet_service.go to the .openapi-generator-ignore to avoid overwriting this service implementation when updating open api generation.
+
+	// TODO: Uncomment the next line to return response Response(200, []Pet{}) or use other options such as http.Ok ...
+	// return Response(200, []Pet{}), nil
+
+	// TODO: Uncomment the next line to return response Response(400, {}) or use other options such as http.Ok ...
+	// return Response(400, nil),nil
+
+	return Response(http.StatusNotImplemented, nil), errors.New("FilterPetsByCategory method not implemented")
+}
+
 // FindPetsByStatus - Finds Pets by status
 func (s *PetAPIService) FindPetsByStatus(ctx context.Context, status []string) (ImplResponse, error) {
 	// TODO - update FindPetsByStatus with the required logic for this service method.

samples/server/petstore/go-api-server/go/model_gender.go

@@ -0,0 +1,66 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Generated by: OpenAPI Generator (https://openapi-generator.tech)
+ */
+
+package petstoreserver
+
+
+import (
+	"fmt"
+)
+
+
+
+type Gender string
+
+// List of Gender
+const (
+	MALE Gender = "male"
+	FEMALE Gender = "female"
+)
+
+// AllowedGenderEnumValues is all the allowed values of Gender enum
+var AllowedGenderEnumValues = []Gender{
+	"male",
+	"female",
+}
+
+// validGenderEnumValue provides a map of Genders for fast verification of use input
+var validGenderEnumValues = map[Gender]struct{}{
+	"male": {},
+	"female": {},
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v Gender) IsValid() bool {
+	_, ok := validGenderEnumValues[v]
+	return ok
+}
+
+// NewGenderFromValue returns a pointer to a valid Gender
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewGenderFromValue(v string) (Gender, error) {
+	ev := Gender(v)
+	if ev.IsValid() {
+		return ev, nil
+	} else {
+		return "", fmt.Errorf("invalid value '%v' for Gender: valid values are %v", v, AllowedGenderEnumValues)
+	}
+}
+
+
+
+// AssertGenderRequired checks if the required fields are not zero-ed
+func AssertGenderRequired(obj Gender) error {
+	return nil
+}
+
+// AssertGenderConstraints checks if the values respects the defined constraints
+func AssertGenderConstraints(obj Gender) error {
+	return nil
+}

samples/server/petstore/go-api-server/go/model_species.go

@@ -0,0 +1,75 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Generated by: OpenAPI Generator (https://openapi-generator.tech)
+ */
+
+package petstoreserver
+
+
+import (
+	"fmt"
+)
+
+
+
+type Species string
+
+// List of Species
+const (
+	CAT Species = "cat"
+	DOG Species = "dog"
+	FISH Species = "fish"
+	GOAT Species = "goat"
+	PIG Species = "pig"
+)
+
+// AllowedSpeciesEnumValues is all the allowed values of Species enum
+var AllowedSpeciesEnumValues = []Species{
+	"cat",
+	"dog",
+	"fish",
+	"goat",
+	"pig",
+}
+
+// validSpeciesEnumValue provides a map of Speciess for fast verification of use input
+var validSpeciesEnumValues = map[Species]struct{}{
+	"cat": {},
+	"dog": {},
+	"fish": {},
+	"goat": {},
+	"pig": {},
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v Species) IsValid() bool {
+	_, ok := validSpeciesEnumValues[v]
+	return ok
+}
+
+// NewSpeciesFromValue returns a pointer to a valid Species
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewSpeciesFromValue(v string) (Species, error) {
+	ev := Species(v)
+	if ev.IsValid() {
+		return ev, nil
+	} else {
+		return "", fmt.Errorf("invalid value '%v' for Species: valid values are %v", v, AllowedSpeciesEnumValues)
+	}
+}
+
+
+
+// AssertSpeciesRequired checks if the required fields are not zero-ed
+func AssertSpeciesRequired(obj Species) error {
+	return nil
+}
+
+// AssertSpeciesConstraints checks if the values respects the defined constraints
+func AssertSpeciesConstraints(obj Species) error {
+	return nil
+}

samples/server/petstore/go-chi-server/.openapi-generator/FILES

@@ -16,10 +16,12 @@ go/logger.go
 go/model_an_object.go
 go/model_api_response.go
 go/model_category.go
+go/model_gender.go
 go/model_order.go
 go/model_order_info.go
 go/model_pet.go
 go/model_special_info.go
+go/model_species.go
 go/model_tag.go
 go/model_user.go
 go/routers.go

samples/server/petstore/go-chi-server/api/openapi.yaml

@@ -158,6 +158,54 @@ paths:
       summary: Finds Pets by tags
       tags:
       - pet
+  /pet/filterPets/{gender}:
+    get:
+      operationId: filterPetsByCategory
+      parameters:
+      - explode: false
+        in: path
+        name: gender
+        required: true
+        schema:
+          $ref: '#/components/schemas/Gender'
+        style: simple
+      - description: Species to filter by
+        explode: false
+        in: query
+        name: species
+        required: true
+        schema:
+          $ref: '#/components/schemas/Species'
+        style: form
+      - description: Species to omit from results
+        explode: false
+        in: query
+        name: notSpecies
+        required: false
+        schema:
+          items:
+            $ref: '#/components/schemas/Species'
+          type: array
+        style: form
+      responses:
+        "200":
+          content:
+            application/xml:
+              schema:
+                items:
+                  $ref: '#/components/schemas/Pet'
+                type: array
+            application/json:
+              schema:
+                items:
+                  $ref: '#/components/schemas/Pet'
+                type: array
+          description: successful operation
+        "400":
+          description: Invalid species value
+      summary: Finds Pets
+      tags:
+      - pet
   /pet/{petId}:
     delete:
       description: ""
@@ -1020,6 +1068,20 @@ components:
       type: object
       xml:
         name: Pet
+    Species:
+      enum:
+      - cat
+      - dog
+      - fish
+      - goat
+      - pig
+      title: The species of a pet
+      type: string
+    Gender:
+      enum:
+      - male
+      - female
+      type: string
     ApiResponse:
       description: Describes the result of uploading an image resource
       example:

samples/server/petstore/go-chi-server/go/api.go

@@ -23,6 +23,7 @@ import (
 type PetAPIRouter interface { 
 	AddPet(http.ResponseWriter, *http.Request)
 	DeletePet(http.ResponseWriter, *http.Request)
+	FilterPetsByCategory(http.ResponseWriter, *http.Request)
 	FindPetsByStatus(http.ResponseWriter, *http.Request)
 	// Deprecated
 	FindPetsByTags(http.ResponseWriter, *http.Request)
@@ -63,6 +64,7 @@ type UserAPIRouter interface {
 type PetAPIServicer interface { 
 	AddPet(context.Context, Pet) (ImplResponse, error)
 	DeletePet(context.Context, int64, string) (ImplResponse, error)
+	FilterPetsByCategory(context.Context, Gender, Species, []Species) (ImplResponse, error)
 	FindPetsByStatus(context.Context, []string) (ImplResponse, error)
 	// Deprecated
 	FindPetsByTags(context.Context, []string) (ImplResponse, error)

samples/server/petstore/go-chi-server/go/api_pet.go

@@ -60,6 +60,11 @@ func (c *PetAPIController) Routes() Routes {
 			"/v2/pet/{petId}",
 			c.DeletePet,
 		},
+		"FilterPetsByCategory": Route{
+			strings.ToUpper("Get"),
+			"/v2/pet/filterPets/{gender}",
+			c.FilterPetsByCategory,
+		},
 		"FindPetsByStatus": Route{
 			strings.ToUpper("Get"),
 			"/v2/pet/findByStatus",
@@ -146,10 +151,53 @@ func (c *PetAPIController) DeletePet(w http.ResponseWriter, r *http.Request) {
 	EncodeJSONResponse(result.Body, &result.Code, result.Headers, w)
 }
 
+// FilterPetsByCategory - Finds Pets
+func (c *PetAPIController) FilterPetsByCategory(w http.ResponseWriter, r *http.Request) {
+	query := r.URL.Query()
+	genderParam, err := NewGenderFromValue(chi.URLParam(r, "gender"))
+	if err != nil {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	if !query.Has("species"){
+		c.errorHandler(w, r, &RequiredError{"species"}, nil)
+		return
+	}
+	speciesParam, err := NewSpeciesFromValue(query.Get("species"))
+	if err != nil {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	var notSpeciesParam []Species
+	if query.Has("notSpecies") {
+		paramSplits := strings.Split(query.Get("notSpecies"), ",")
+		notSpeciesParam = make([]Species, 0, len(paramSplits))
+		for _, param := range paramSplits {
+			paramEnum, err := NewSpeciesFromValue(param)
+			if err != nil {
+				c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+				return
+			}
+			notSpeciesParam = append(notSpeciesParam, paramEnum)
+		}
+	}
+	result, err := c.service.FilterPetsByCategory(r.Context(), genderParam, speciesParam, notSpeciesParam)
+	// If an error occurred, encode the error with the status code
+	if err != nil {
+		c.errorHandler(w, r, err, &result)
+		return
+	}
+	// If no error, encode the body and the result code
+	EncodeJSONResponse(result.Body, &result.Code, result.Headers, w)
+}
+
 // FindPetsByStatus - Finds Pets by status
 func (c *PetAPIController) FindPetsByStatus(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	statusParam := strings.Split(query.Get("status"), ",")
+	var statusParam []string
+	if query.Has("status") {
+		statusParam = strings.Split(query.Get("status"), ",")
+	}
 	result, err := c.service.FindPetsByStatus(r.Context(), statusParam)
 	// If an error occurred, encode the error with the status code
 	if err != nil {
@@ -164,7 +212,10 @@ func (c *PetAPIController) FindPetsByStatus(w http.ResponseWriter, r *http.Reque
 // Deprecated
 func (c *PetAPIController) FindPetsByTags(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	tagsParam := strings.Split(query.Get("tags"), ",")
+	var tagsParam []string
+	if query.Has("tags") {
+		tagsParam = strings.Split(query.Get("tags"), ",")
+	}
 	result, err := c.service.FindPetsByTags(r.Context(), tagsParam)
 	// If an error occurred, encode the error with the status code
 	if err != nil {

samples/server/petstore/go-chi-server/go/api_pet_service.go

@@ -52,6 +52,20 @@ func (s *PetAPIService) DeletePet(ctx context.Context, petId int64, apiKey strin
 	return Response(http.StatusNotImplemented, nil), errors.New("DeletePet method not implemented")
 }
 
+// FilterPetsByCategory - Finds Pets
+func (s *PetAPIService) FilterPetsByCategory(ctx context.Context, gender Gender, species Species, notSpecies []Species) (ImplResponse, error) {
+	// TODO - update FilterPetsByCategory with the required logic for this service method.
+	// Add api_pet_service.go to the .openapi-generator-ignore to avoid overwriting this service implementation when updating open api generation.
+
+	// TODO: Uncomment the next line to return response Response(200, []Pet{}) or use other options such as http.Ok ...
+	// return Response(200, []Pet{}), nil
+
+	// TODO: Uncomment the next line to return response Response(400, {}) or use other options such as http.Ok ...
+	// return Response(400, nil),nil
+
+	return Response(http.StatusNotImplemented, nil), errors.New("FilterPetsByCategory method not implemented")
+}
+
 // FindPetsByStatus - Finds Pets by status
 func (s *PetAPIService) FindPetsByStatus(ctx context.Context, status []string) (ImplResponse, error) {
 	// TODO - update FindPetsByStatus with the required logic for this service method.

samples/server/petstore/go-chi-server/go/model_gender.go

@@ -0,0 +1,66 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Generated by: OpenAPI Generator (https://openapi-generator.tech)
+ */
+
+package petstoreserver
+
+
+import (
+	"fmt"
+)
+
+
+
+type Gender string
+
+// List of Gender
+const (
+	MALE Gender = "male"
+	FEMALE Gender = "female"
+)
+
+// AllowedGenderEnumValues is all the allowed values of Gender enum
+var AllowedGenderEnumValues = []Gender{
+	"male",
+	"female",
+}
+
+// validGenderEnumValue provides a map of Genders for fast verification of use input
+var validGenderEnumValues = map[Gender]struct{}{
+	"male": {},
+	"female": {},
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v Gender) IsValid() bool {
+	_, ok := validGenderEnumValues[v]
+	return ok
+}
+
+// NewGenderFromValue returns a pointer to a valid Gender
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewGenderFromValue(v string) (Gender, error) {
+	ev := Gender(v)
+	if ev.IsValid() {
+		return ev, nil
+	} else {
+		return "", fmt.Errorf("invalid value '%v' for Gender: valid values are %v", v, AllowedGenderEnumValues)
+	}
+}
+
+
+
+// AssertGenderRequired checks if the required fields are not zero-ed
+func AssertGenderRequired(obj Gender) error {
+	return nil
+}
+
+// AssertGenderConstraints checks if the values respects the defined constraints
+func AssertGenderConstraints(obj Gender) error {
+	return nil
+}

samples/server/petstore/go-chi-server/go/model_species.go

@@ -0,0 +1,75 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Generated by: OpenAPI Generator (https://openapi-generator.tech)
+ */
+
+package petstoreserver
+
+
+import (
+	"fmt"
+)
+
+
+
+type Species string
+
+// List of Species
+const (
+	CAT Species = "cat"
+	DOG Species = "dog"
+	FISH Species = "fish"
+	GOAT Species = "goat"
+	PIG Species = "pig"
+)
+
+// AllowedSpeciesEnumValues is all the allowed values of Species enum
+var AllowedSpeciesEnumValues = []Species{
+	"cat",
+	"dog",
+	"fish",
+	"goat",
+	"pig",
+}
+
+// validSpeciesEnumValue provides a map of Speciess for fast verification of use input
+var validSpeciesEnumValues = map[Species]struct{}{
+	"cat": {},
+	"dog": {},
+	"fish": {},
+	"goat": {},
+	"pig": {},
+}
+
+// IsValid return true if the value is valid for the enum, false otherwise
+func (v Species) IsValid() bool {
+	_, ok := validSpeciesEnumValues[v]
+	return ok
+}
+
+// NewSpeciesFromValue returns a pointer to a valid Species
+// for the value passed as argument, or an error if the value passed is not allowed by the enum
+func NewSpeciesFromValue(v string) (Species, error) {
+	ev := Species(v)
+	if ev.IsValid() {
+		return ev, nil
+	} else {
+		return "", fmt.Errorf("invalid value '%v' for Species: valid values are %v", v, AllowedSpeciesEnumValues)
+	}
+}
+
+
+
+// AssertSpeciesRequired checks if the required fields are not zero-ed
+func AssertSpeciesRequired(obj Species) error {
+	return nil
+}
+
+// AssertSpeciesConstraints checks if the values respects the defined constraints
+func AssertSpeciesConstraints(obj Species) error {
+	return nil
+}