Add tests with optional body for go-server (#22034)

* add tests with optional body for go-server

* update workfllow

.github/workflows/samples-go.yaml

@@ -6,13 +6,13 @@ on:
       - 'samples/server/petstore/go-echo-server/**'
       - 'samples/server/petstore/go-api-server/**'
       - 'samples/server/petstore/go-chi-server/**'
-      - 'samples/server/others/go-server/no-body-path-params/**'
+      - 'samples/server/others/go-server/**'
   pull_request:
     paths:
       - 'samples/server/petstore/go-echo-server/**'
       - 'samples/server/petstore/go-api-server/**'
       - 'samples/server/petstore/go-chi-server/**'
-      - 'samples/server/others/go-server/no-body-path-params/**'
+      - 'samples/server/others/go-server/**'
 
 jobs:
   build:
@@ -26,6 +26,7 @@ jobs:
           - samples/server/petstore/go-api-server/
           - samples/server/petstore/go-chi-server/
           - samples/server/others/go-server/no-body-path-params/
+          - samples/server/others/go-server/optional-body/
     steps:
       - uses: actions/checkout@v5
       - uses: actions/setup-go@v6
@@ -58,4 +59,4 @@ jobs:
           go mod tidy
       - name: Run tests
         working-directory: ${{ matrix.sample }}
-        run: go test ./samples_tests -v
+        run: go test ./samples_tests -v

bin/configs/go-server-optional-body.yaml

@@ -0,0 +1,8 @@
+generatorName: go-server
+outputDir: samples/server/others/go-server/optional-body
+inputSpec: modules/openapi-generator/src/test/resources/3_0/optional_body.yaml
+templateDir: modules/openapi-generator/src/main/resources/go-server
+additionalProperties:
+  hideGenerationTimestamp: "true"
+  packageName: petstoreserver
+  addResponseHeaders: true

modules/openapi-generator/src/test/resources/3_0/optional_body.yaml

@@ -0,0 +1,35 @@
+openapi: 3.0.3
+info:
+  title: optional body
+  version: 1.0.1
+servers:
+  - url: https://api.123.com/api/v1
+tags:
+  - name: just-api
+    description: Everything about API functions
+paths:
+  /silly:
+    post:
+      tags:
+        - just-api
+      operationId: send_optional_payload
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/Payload"
+      responses:
+        '200':
+          description: Successful operation
+          content:
+            application/text:
+              schema:
+                type: string
+components:
+  schemas:
+    Payload:
+      type: object
+      properties:
+        token:
+          type: string
+          description: Some kind of token - usually received by Email

samples/server/others/go-server/optional-body/.openapi-generator-ignore

@@ -0,0 +1,23 @@
+# OpenAPI Generator Ignore
+# Generated by openapi-generator https://github.com/openapitools/openapi-generator
+
+# Use this file to prevent files from being overwritten by the generator.
+# The patterns follow closely to .gitignore or .dockerignore.
+
+# As an example, the C# client generator defines ApiClient.cs.
+# You can make changes and tell OpenAPI Generator to ignore just this file by uncommenting the following line:
+#ApiClient.cs
+
+# You can match any string of characters against a directory, file or extension with a single asterisk (*):
+#foo/*/qux
+# The above matches foo/bar/qux and foo/baz/qux, but not foo/bar/baz/qux
+
+# You can recursively match patterns against a directory, file or extension with a double asterisk (**):
+#foo/**/qux
+# This matches foo/bar/qux, foo/baz/qux, and foo/bar/baz/qux
+
+# You can also negate patterns with an exclamation (!).
+# For example, you can ignore all files in a docs folder with the file extension .md:
+#docs/*.md
+# Then explicitly reverse the ignore rule for a single file:
+#!docs/README.md

samples/server/others/go-server/optional-body/.openapi-generator/FILES

@@ -0,0 +1,14 @@
+Dockerfile
+README.md
+api/openapi.yaml
+go.mod
+go/api.go
+go/api_just_api.go
+go/api_just_api_service.go
+go/error.go
+go/helpers.go
+go/impl.go
+go/logger.go
+go/model_payload.go
+go/routers.go
+main.go

samples/server/others/go-server/optional-body/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.16.0-SNAPSHOT

samples/server/others/go-server/optional-body/Dockerfile

@@ -0,0 +1,15 @@
+FROM golang:1.19 AS build
+WORKDIR /go/src
+COPY go ./go
+COPY main.go .
+COPY go.sum .
+COPY go.mod .
+
+ENV CGO_ENABLED=0
+
+RUN go build -o petstoreserver .
+
+FROM scratch AS runtime
+COPY --from=build /go/src/petstoreserver ./
+EXPOSE 8080/tcp
+ENTRYPOINT ["./petstoreserver"]

samples/server/others/go-server/optional-body/README.md

@@ -0,0 +1,35 @@
+# Go API Server for petstoreserver
+
+No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+
+## Overview
+This server was generated by the [openapi-generator]
+(https://openapi-generator.tech) project.
+By using the [OpenAPI-Spec](https://github.com/OAI/OpenAPI-Specification) from a remote server, you can easily generate a server stub.
+
+To see how to make this your own, look here:
+
+[README](https://openapi-generator.tech)
+
+- API version: 1.0.1
+- Generator version: 7.16.0-SNAPSHOT
+
+
+### Running the server
+To run the server, follow these simple steps:
+
+```
+go run main.go
+```
+
+The server will be available on `http://localhost:8080`.
+
+To run the server in a docker container
+```
+docker build --network=host -t petstoreserver .
+```
+
+Once image is built use
+```
+docker run --rm -it petstoreserver
+```

samples/server/others/go-server/optional-body/api/openapi.yaml

@@ -0,0 +1,37 @@
+openapi: 3.0.3
+info:
+  title: optional body
+  version: 1.0.1
+servers:
+- url: https://api.123.com/api/v1
+tags:
+- description: Everything about API functions
+  name: just-api
+paths:
+  /silly:
+    post:
+      operationId: send_optional_payload
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/Payload"
+      responses:
+        "200":
+          content:
+            application/text:
+              schema:
+                type: string
+          description: Successful operation
+      tags:
+      - just-api
+components:
+  schemas:
+    Payload:
+      example:
+        token: token
+      properties:
+        token:
+          description: Some kind of token - usually received by Email
+          type: string
+      type: object

samples/server/others/go-server/optional-body/go.mod

@@ -0,0 +1,4 @@
+module github.com/GIT_USER_ID/GIT_REPO_ID
+
+go 1.18
+

samples/server/others/go-server/optional-body/go/api.go

@@ -0,0 +1,34 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"context"
+	"net/http"
+)
+
+
+
+// JustApiAPIRouter defines the required methods for binding the api requests to a responses for the JustApiAPI
+// The JustApiAPIRouter implementation should parse necessary information from the http request,
+// pass the data to a JustApiAPIServicer to perform the required actions, then write the service results to the http response.
+type JustApiAPIRouter interface { 
+	SendOptionalPayload(http.ResponseWriter, *http.Request)
+}
+
+
+// JustApiAPIServicer defines the api actions for the JustApiAPI service
+// This interface intended to stay up to date with the openapi yaml used to generate it,
+// while the service implementation can be ignored with the .openapi-generator-ignore file
+// and updated with the logic required for the API.
+type JustApiAPIServicer interface { 
+	SendOptionalPayload(context.Context, Payload) (ImplResponse, error)
+}

samples/server/others/go-server/optional-body/go/api_just_api.go

@@ -0,0 +1,102 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+)
+
+// JustApiAPIController binds http requests to an api service and writes the service results to the http response
+type JustApiAPIController struct {
+	service JustApiAPIServicer
+	errorHandler ErrorHandler
+}
+
+// JustApiAPIOption for how the controller is set up.
+type JustApiAPIOption func(*JustApiAPIController)
+
+// WithJustApiAPIErrorHandler inject ErrorHandler into controller
+func WithJustApiAPIErrorHandler(h ErrorHandler) JustApiAPIOption {
+	return func(c *JustApiAPIController) {
+		c.errorHandler = h
+	}
+}
+
+// NewJustApiAPIController creates a default api controller
+func NewJustApiAPIController(s JustApiAPIServicer, opts ...JustApiAPIOption) *JustApiAPIController {
+	controller := &JustApiAPIController{
+		service:      s,
+		errorHandler: DefaultErrorHandler,
+	}
+
+	for _, opt := range opts {
+		opt(controller)
+	}
+
+	return controller
+}
+
+// Routes returns all the api routes for the JustApiAPIController
+func (c *JustApiAPIController) Routes() Routes {
+	return Routes{
+		"SendOptionalPayload": Route{
+			"SendOptionalPayload",
+			strings.ToUpper("Post"),
+			"/api/v1/silly",
+			c.SendOptionalPayload,
+		},
+	}
+}
+
+// OrderedRoutes returns all the api routes in a deterministic order for the JustApiAPIController
+func (c *JustApiAPIController) OrderedRoutes() []Route {
+	return []Route{
+		Route{
+			"SendOptionalPayload",
+			strings.ToUpper("Post"),
+			"/api/v1/silly",
+			c.SendOptionalPayload,
+		},
+	}
+}
+
+
+
+// SendOptionalPayload - 
+func (c *JustApiAPIController) SendOptionalPayload(w http.ResponseWriter, r *http.Request) {
+	var payloadParam Payload
+	d := json.NewDecoder(r.Body)
+	d.DisallowUnknownFields()
+	if err := d.Decode(&payloadParam); err != nil && !errors.Is(err, io.EOF) {
+		c.errorHandler(w, r, &ParsingError{Err: err}, nil)
+		return
+	}
+	if err := AssertPayloadRequired(payloadParam); err != nil {
+		c.errorHandler(w, r, err, nil)
+		return
+	}
+	if err := AssertPayloadConstraints(payloadParam); err != nil {
+		c.errorHandler(w, r, err, nil)
+		return
+	}
+	result, err := c.service.SendOptionalPayload(r.Context(), payloadParam)
+	// 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)
+}

samples/server/others/go-server/optional-body/go/api_just_api_service.go

@@ -0,0 +1,39 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"context"
+	"net/http"
+	"errors"
+)
+
+// JustApiAPIService is a service that implements the logic for the JustApiAPIServicer
+// This service should implement the business logic for every endpoint for the JustApiAPI API.
+// Include any external packages or services that will be required by this service.
+type JustApiAPIService struct {
+}
+
+// NewJustApiAPIService creates a default api service
+func NewJustApiAPIService() *JustApiAPIService {
+	return &JustApiAPIService{}
+}
+
+// SendOptionalPayload - 
+func (s *JustApiAPIService) SendOptionalPayload(ctx context.Context, payload Payload) (ImplResponse, error) {
+	// TODO - update SendOptionalPayload with the required logic for this service method.
+	// Add api_just_api_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, string{}) or use other options such as http.Ok ...
+	// return Response(200, string{}), nil
+
+	return Response(http.StatusNotImplemented, nil), errors.New("SendOptionalPayload method not implemented")
+}

samples/server/others/go-server/optional-body/go/error.go

@@ -0,0 +1,74 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+var (
+	// ErrTypeAssertionError is thrown when type an interface does not match the asserted type
+	ErrTypeAssertionError = errors.New("unable to assert type")
+)
+
+// ParsingError indicates that an error has occurred when parsing request parameters
+type ParsingError struct {
+	Param string
+	Err   error
+}
+
+func (e *ParsingError) Unwrap() error {
+	return e.Err
+}
+
+func (e *ParsingError) Error() string {
+	if e.Param == "" {
+		return e.Err.Error()
+	}
+
+	return e.Param + ": " + e.Err.Error()
+}
+
+// RequiredError indicates that an error has occurred when parsing request parameters
+type RequiredError struct {
+	Field string
+}
+
+func (e *RequiredError) Error() string {
+	return fmt.Sprintf("required field '%s' is zero value.", e.Field)
+}
+
+// ErrorHandler defines the required method for handling error. You may implement it and inject this into a controller if
+// you would like errors to be handled differently from the DefaultErrorHandler
+type ErrorHandler func(w http.ResponseWriter, r *http.Request, err error, result *ImplResponse)
+
+// DefaultErrorHandler defines the default logic on how to handle errors from the controller. Any errors from parsing
+// request params will return a StatusBadRequest. Otherwise, the error code originating from the servicer will be used.
+func DefaultErrorHandler(w http.ResponseWriter, _ *http.Request, err error, result *ImplResponse) {
+	var parsingErr *ParsingError
+	if ok := errors.As(err, &parsingErr); ok {
+		// Handle parsing errors
+		_ = EncodeJSONResponse(err.Error(), func(i int) *int { return &i }(http.StatusBadRequest), map[string][]string{}, w)
+		return
+	}
+
+	var requiredErr *RequiredError
+	if ok := errors.As(err, &requiredErr); ok {
+		// Handle missing required errors
+		_ = EncodeJSONResponse(err.Error(), func(i int) *int { return &i }(http.StatusUnprocessableEntity), map[string][]string{}, w)
+		return
+	} 
+
+	// Handle all other errors
+	_ = EncodeJSONResponse(err.Error(), &result.Code, result.Headers, w)
+}

samples/server/others/go-server/optional-body/go/helpers.go

@@ -0,0 +1,371 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"mime/multipart"
+	"net/http"
+	"net/url"
+	"os"
+	"reflect"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const errMsgRequiredMissing = "required parameter is missing"
+const errMsgMinValueConstraint = "provided parameter is not respecting minimum value constraint"
+const errMsgMaxValueConstraint = "provided parameter is not respecting maximum value constraint"
+
+// Response return a ImplResponse struct filled
+func Response(code int, body interface{}) ImplResponse {
+	return ImplResponse {
+		Code: code,
+		Headers: nil,
+		Body: body,
+	}
+}
+
+// ResponseWithHeaders return a ImplResponse struct filled, including headers
+func ResponseWithHeaders(code int, headers map[string][]string, body interface{}) ImplResponse {
+	return ImplResponse {
+		Code: code,
+		Headers: headers,
+		Body: body,
+	}
+}
+
+// IsZeroValue checks if the val is the zero-ed value.
+func IsZeroValue(val interface{}) bool {
+	return val == nil || reflect.DeepEqual(val, reflect.Zero(reflect.TypeOf(val)).Interface())
+}
+
+// AssertRecurseInterfaceRequired recursively checks each struct in a slice against the callback.
+// This method traverse nested slices in a preorder fashion.
+func AssertRecurseInterfaceRequired[T any](obj interface{}, callback func(T) error) error {
+	return AssertRecurseValueRequired(reflect.ValueOf(obj), callback)
+}
+
+// AssertRecurseValueRequired checks each struct in the nested slice against the callback.
+// This method traverse nested slices in a preorder fashion. ErrTypeAssertionError is thrown if
+// the underlying struct does not match type T.
+func AssertRecurseValueRequired[T any](value reflect.Value, callback func(T) error) error {
+	switch value.Kind() {
+	// If it is a struct we check using callback
+	case reflect.Struct:
+		obj, ok := value.Interface().(T)
+		if !ok {
+			return ErrTypeAssertionError
+		}
+
+		if err := callback(obj); err != nil {
+			return err
+		}
+
+	// If it is a slice we continue recursion
+	case reflect.Slice:
+		for i := 0; i < value.Len(); i++ {
+			if err := AssertRecurseValueRequired(value.Index(i), callback); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// EncodeJSONResponse uses the json encoder to write an interface to the http response with an optional status code
+func EncodeJSONResponse(i interface{}, status *int, headers map[string][]string, w http.ResponseWriter) error {
+	wHeader := w.Header()
+	for key, values := range headers {
+		for _, value := range values {
+			wHeader.Add(key, value)
+		}
+	}
+
+	f, ok := i.(*os.File)
+	if ok {
+		data, err := io.ReadAll(f)
+		if err != nil {
+			return err
+		}
+		wHeader.Set("Content-Type", http.DetectContentType(data))
+		wHeader.Set("Content-Disposition", "attachment; filename="+f.Name())
+		if status != nil {
+			w.WriteHeader(*status)
+		} else {
+			w.WriteHeader(http.StatusOK)
+		}
+		_, err = w.Write(data)
+		return err
+	}
+	wHeader.Set("Content-Type", "application/json; charset=UTF-8")
+
+	if status != nil {
+		w.WriteHeader(*status)
+	} else {
+		w.WriteHeader(http.StatusOK)
+	}
+
+	if i != nil {
+		return json.NewEncoder(w).Encode(i)
+	}
+
+	return nil
+}
+
+// ReadFormFileToTempFile reads file data from a request form and writes it to a temporary file
+func ReadFormFileToTempFile(r *http.Request, key string) (*os.File, error) {
+	_, fileHeader, err := r.FormFile(key)
+	if err != nil {
+		return nil, err
+	}
+
+	return readFileHeaderToTempFile(fileHeader)
+}
+
+// ReadFormFilesToTempFiles reads files array data from a request form and writes it to a temporary files
+func ReadFormFilesToTempFiles(r *http.Request, key string) ([]*os.File, error) {
+	if err := r.ParseMultipartForm(32 << 20); err != nil {
+		return nil, err
+	}
+
+	files := make([]*os.File, 0, len(r.MultipartForm.File[key]))
+
+	for _, fileHeader := range r.MultipartForm.File[key] {
+		file, err := readFileHeaderToTempFile(fileHeader)
+		if err != nil {
+			return nil, err
+		}
+
+		files = append(files, file)
+	}
+
+	return files, nil
+}
+
+// readFileHeaderToTempFile reads multipart.FileHeader and writes it to a temporary file
+func readFileHeaderToTempFile(fileHeader *multipart.FileHeader) (*os.File, error) {
+	formFile, err := fileHeader.Open()
+	if err != nil {
+		return nil, err
+	}
+
+	defer formFile.Close()
+
+	// Use .* as suffix, because the asterisk is a placeholder for the random value,
+	// and the period allows consumers of this file to remove the suffix to obtain the original file name
+	file, err := os.CreateTemp("", fileHeader.Filename+".*")
+	if err != nil {
+		return nil, err
+	}
+
+	defer file.Close()
+
+	_, err = io.Copy(file, formFile)
+	if err != nil {
+		return nil, err
+	}
+	
+	return file, nil
+}
+
+func parseTimes(param string) ([]time.Time, error) {
+	splits := strings.Split(param, ",")
+	times := make([]time.Time, 0, len(splits))
+	for _, v := range splits {
+		t, err := parseTime(v)
+		if err != nil {
+			return nil, err
+		}
+		times = append(times, t)
+	}
+	return times, nil
+}
+
+// parseTime will parses a string parameter into a time.Time using the RFC3339 format
+func parseTime(param string) (time.Time, error) {
+	if param == "" {
+		return time.Time{}, nil
+	}
+	return time.Parse(time.RFC3339, param)
+}
+
+type Number interface {
+	~int32 | ~int64 | ~float32 | ~float64
+}
+
+type ParseString[T Number | string | bool] func(v string) (T, error)
+
+// parseFloat64 parses a string parameter to an float64.
+func parseFloat64(param string) (float64, error) {
+	if param == "" {
+		return 0, nil
+	}
+
+	return strconv.ParseFloat(param, 64)
+}
+
+// parseFloat32 parses a string parameter to an float32.
+func parseFloat32(param string) (float32, error) {
+	if param == "" {
+		return 0, nil
+	}
+
+	v, err := strconv.ParseFloat(param, 32)
+	return float32(v), err
+}
+
+// parseInt64 parses a string parameter to an int64.
+func parseInt64(param string) (int64, error) {
+	if param == "" {
+		return 0, nil
+	}
+
+	return strconv.ParseInt(param, 10, 64)
+}
+
+// parseInt32 parses a string parameter to an int32.
+func parseInt32(param string) (int32, error) {
+	if param == "" {
+		return 0, nil
+	}
+
+	val, err := strconv.ParseInt(param, 10, 32)
+	return int32(val), err
+}
+
+// parseBool parses a string parameter to an bool.
+func parseBool(param string) (bool, error) {
+	if param == "" {
+		return false, nil
+	}
+
+	return strconv.ParseBool(param)
+}
+
+type Operation[T Number | string | bool] func(actual string) (T, bool, error)
+
+func WithRequire[T Number | string | bool](parse ParseString[T]) Operation[T] {
+	var empty T
+	return func(actual string) (T, bool, error) {
+		if actual == "" {
+			return empty, false, errors.New(errMsgRequiredMissing)
+		}
+
+		v, err := parse(actual)
+		return v, false, err
+	}
+}
+
+func WithDefaultOrParse[T Number | string | bool](def T, parse ParseString[T]) Operation[T] {
+	return func(actual string) (T, bool, error) {
+		if actual == "" {
+			return def, true, nil
+		}
+
+		v, err := parse(actual)
+		return v, false, err
+	}
+}
+
+func WithParse[T Number | string | bool](parse ParseString[T]) Operation[T] {
+	return func(actual string) (T, bool, error) {
+		v, err := parse(actual)
+		return v, false, err
+	}
+}
+
+type Constraint[T Number | string | bool] func(actual T) error
+
+func WithMinimum[T Number](expected T) Constraint[T] {
+	return func(actual T) error {
+		if actual < expected {
+			return errors.New(errMsgMinValueConstraint)
+		}
+
+		return nil
+	}
+}
+
+func WithMaximum[T Number](expected T) Constraint[T] {
+	return func(actual T) error {
+		if actual > expected {
+			return errors.New(errMsgMaxValueConstraint)
+		}
+
+		return nil
+	}
+}
+
+// parseNumericParameter parses a numeric parameter to its respective type.
+func parseNumericParameter[T Number](param string, fn Operation[T], checks ...Constraint[T]) (T, error) {
+	v, ok, err := fn(param)
+	if err != nil {
+		return 0, err
+	}
+
+	if !ok {
+		for _, check := range checks {
+			if err := check(v); err != nil {
+				return 0, err
+			}
+		}
+	}
+
+	return v, nil
+}
+
+// parseBoolParameter parses a string parameter to a bool
+func parseBoolParameter(param string, fn Operation[bool]) (bool, error) {
+	v, _, err := fn(param)
+	return v, err
+}
+
+// parseNumericArrayParameter parses a string parameter containing array of values to its respective type.
+func parseNumericArrayParameter[T Number](param, delim string, required bool, fn Operation[T], checks ...Constraint[T]) ([]T, error) {
+	if param == "" {
+		if required {
+			return nil, errors.New(errMsgRequiredMissing)
+		}
+
+		return nil, nil
+	}
+
+	str := strings.Split(param, delim)
+	values := make([]T, len(str))
+
+	for i, s := range str {
+		v, ok, err := fn(s)
+		if err != nil {
+			return nil, err
+		}
+
+		if !ok {
+			for _, check := range checks {
+				if err := check(v); err != nil {
+					return nil, err
+				}
+			}
+		}
+
+		values[i] = v
+	}
+
+	return values, nil
+}
+
+// parseQuery parses query parameters and returns an error if any malformed value pairs are encountered.
+func parseQuery(rawQuery string) (url.Values, error) {
+	return url.ParseQuery(rawQuery)
+}

samples/server/others/go-server/optional-body/go/impl.go

@@ -0,0 +1,18 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+// ImplResponse defines an implementation response with error code and the associated body
+type ImplResponse struct {
+	Code int
+	Headers map[string][]string
+	Body interface{}
+}

samples/server/others/go-server/optional-body/go/logger.go

@@ -0,0 +1,33 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"net/http"
+	"log"
+	"time"
+)
+
+func Logger(inner http.Handler, name string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+
+		inner.ServeHTTP(w, r)
+
+		log.Printf(
+			"%s %s %s %s",
+			r.Method,
+			r.RequestURI,
+			name,
+			time.Since(start),
+		)
+	})
+}

samples/server/others/go-server/optional-body/go/model_payload.go

@@ -0,0 +1,30 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+
+
+
+type Payload struct {
+
+	// Some kind of token - usually received by Email
+	Token string `json:"token,omitempty"`
+}
+
+// AssertPayloadRequired checks if the required fields are not zero-ed
+func AssertPayloadRequired(obj Payload) error {
+	return nil
+}
+
+// AssertPayloadConstraints checks if the values respects the defined constraints
+func AssertPayloadConstraints(obj Payload) error {
+	return nil
+}

samples/server/others/go-server/optional-body/go/routers.go

@@ -0,0 +1,52 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package petstoreserver
+
+import (
+	"net/http"
+	"github.com/gorilla/mux"
+)
+
+// A Route defines the parameters for an api endpoint
+type Route struct {
+	Name        string
+	Method	    string
+	Pattern	    string
+	HandlerFunc http.HandlerFunc
+}
+
+// Routes is a map of defined api endpoints
+type Routes map[string]Route
+
+// Router defines the required methods for retrieving api routes
+type Router interface {
+	Routes() Routes
+	OrderedRoutes() []Route
+}
+
+// NewRouter creates a new router for any number of api routers
+func NewRouter(routers ...Router) *mux.Router {
+	router := mux.NewRouter().StrictSlash(true)
+	for _, api := range routers {
+		for _, route := range api.OrderedRoutes() {
+			var handler http.Handler = route.HandlerFunc
+			handler = Logger(handler, route.Name)
+
+			router.
+				Methods(route.Method).
+				Path(route.Pattern).
+				Name(route.Name).
+				Handler(handler)
+		}
+	}
+
+	return router
+}

samples/server/others/go-server/optional-body/main.go

@@ -0,0 +1,29 @@
+// Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
+
+/*
+ * optional body
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * API version: 1.0.1
+ */
+
+package main
+
+import (
+	"log"
+	"net/http"
+
+	petstoreserver "github.com/GIT_USER_ID/GIT_REPO_ID/go"
+)
+
+func main() {
+	log.Printf("Server started")
+
+	JustApiAPIService := petstoreserver.NewJustApiAPIService()
+	JustApiAPIController := petstoreserver.NewJustApiAPIController(JustApiAPIService)
+
+	router := petstoreserver.NewRouter(JustApiAPIController)
+
+	log.Fatal(http.ListenAndServe(":8080", router))
+}