Resolve several issues in generated Go code (#8491)

* [go] use regular stdlib import names

* [go] support primitive oneOf types

See #8489

* [go] improve pbv/pbr handling

Improves the way pass-by-value and pass-by-reference variables are used.

Closes #8489

* [go] improve generated documentation

* [go] adopt pointer changes in interface

* [go] regenerate sample

* [go] resolve pointer issues

* [go] regenerate clients and avoid pointers on primitive return values

* [go] improve Exec() return value handling

* [go] regernate files

* [go] use go modules

* [go] properly handle polymorph decode

If polymorphism without discriminator was used, the previous code was unable to properly decode the vaules. By using a strict decoder, which rejects unknown fields, type guessing now works.

* [go] make GetActualInstance not panic on nil

* [go] return GenericOpenAPIError as pointer

* [go] clarify helper function godoc

* [go] address test regression error type

* [go] regenerate go samples

* [go] resolve go mod issues and test regressions

* [go] resolve merge conflicts and regenerate

* [go] resolve merge conflicts

* [go] Replace spaces with tabs

Co-authored-by: Jiri Kuncar <[email protected]>

* [go] Replace spaces with tabs

Co-authored-by: Jiri Kuncar <[email protected]>

Co-authored-by: Jiri Kuncar <[email protected]>

Author: aeneasr

modules/openapi-generator/src/main/resources/go/README.mustache

@@ -30,7 +30,7 @@ go get golang.org/x/net/context
 Put the package under your project folder and add the following in import:
 
 ```golang
-import sw "./{{packageName}}"
+import {{packageName}} "{{gitHost}}/{{gitUserId}}/{{gitRepoId}}{{#isGoSubmodule}}/{{packageName}}{{/isGoSubmodule}}"
 ```
 
 To use a proxy, set the environment variable `HTTP_PROXY`:
@@ -48,15 +48,15 @@ Default configuration comes with `Servers` field that contains server objects as
 For using other server than the one defined on index 0 set context value `sw.ContextServerIndex` of type `int`.
 
 ```golang
-ctx := context.WithValue(context.Background(), sw.ContextServerIndex, 1)
+ctx := context.WithValue(context.Background(), {{packageName}}.ContextServerIndex, 1)
 ```
 
 ### Templated Server URL
 
 Templated server URL is formatted using default variables from configuration or from context value `sw.ContextServerVariables` of type `map[string]string`.
 
 ```golang
-ctx := context.WithValue(context.Background(), sw.ContextServerVariables, map[string]string{
+ctx := context.WithValue(context.Background(), {{packageName}}.ContextServerVariables, map[string]string{
 	"basePath": "v2",
 })
 ```
@@ -70,10 +70,10 @@ An operation is uniquely identified by `"{classname}Service.{nickname}"` string.
 Similar rules for overriding default operation server index and variables applies by using `sw.ContextOperationServerIndices` and `sw.ContextOperationServerVariables` context maps.
 
 ```
-ctx := context.WithValue(context.Background(), sw.ContextOperationServerIndices, map[string]int{
+ctx := context.WithValue(context.Background(), {{packageName}}.ContextOperationServerIndices, map[string]int{
 	"{classname}Service.{nickname}": 2,
 })
-ctx = context.WithValue(context.Background(), sw.ContextOperationServerVariables, map[string]map[string]string{
+ctx = context.WithValue(context.Background(), {{packageName}}.ContextOperationServerVariables, map[string]map[string]string{
 	"{classname}Service.{nickname}": {
 		"port": "8443",
 	},
@@ -117,7 +117,7 @@ Note, each API key must be added to a map of `map[string]APIKey` where the key i
 Example
 
 ```golang
-auth := context.WithValue(context.Background(), sw.ContextAccessToken, "BEARERTOKENSTRING")
+auth := context.WithValue(context.Background(), sw.ContextAccessToken, "BEARER_TOKEN_STRING")
 r, err := client.Service.Operation(auth, args)
 ```
 
@@ -142,7 +142,7 @@ r, err := client.Service.Operation(auth, args)
 Example
 
 ```golang
-	authConfig := sw.HttpSignatureAuth{
+	authConfig := client.HttpSignatureAuth{
 		KeyId:                "my-key-id",
 		PrivateKeyPath:       "rsa.pem",
 		Passphrase:           "my-passphrase",

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

@@ -4,17 +4,17 @@ package {{packageName}}
 {{#operations}}
 import (
 	"bytes"
-	_context "context"
-	_ioutil "io/ioutil"
-	_nethttp "net/http"
-	_neturl "net/url"
+	"context"
+	"io/ioutil"
+	"net/http"
+	"net/url"
 {{#imports}}	"{{import}}"
 {{/imports}}
 )
 
 // Linger please
 var (
-	_ _context.Context
+	_ context.Context
 )
 {{#generateInterfaces}}
 
@@ -28,22 +28,22 @@ type {{classname}} interface {
 	{{{unescapedNotes}}}
 	{{/notes}}
 
-	 @param ctx _context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().{{#pathParams}}
+	 @param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().{{#pathParams}}
 	 @param {{paramName}}{{#description}} {{{.}}}{{/description}}{{/pathParams}}
 	 @return {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request
 	{{#isDeprecated}}
 
 	Deprecated
 	{{/isDeprecated}}
 	*/
-	{{{nickname}}}(ctx _context.Context{{#pathParams}}, {{paramName}} {{{dataType}}}{{/pathParams}}) {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request
+	{{{nickname}}}(ctx context.Context{{#pathParams}}, {{paramName}} {{{dataType}}}{{/pathParams}}) {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request
 
 	// {{nickname}}Execute executes the request{{#returnType}}
 	//  @return {{{.}}}{{/returnType}}
 	{{#isDeprecated}}
 	// Deprecated
 	{{/isDeprecated}}
-	{{nickname}}Execute(r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request) ({{#returnType}}{{{.}}}, {{/returnType}}*_nethttp.Response, error)
+	{{nickname}}Execute(r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request) ({{#returnType}}{{^isArray}}{{^returnTypeIsPrimitive}}*{{/returnTypeIsPrimitive}}{{/isArray}}{{{.}}}, {{/returnType}}*http.Response, error)
 	{{/operation}}
 }
 {{/generateInterfaces}}
@@ -53,8 +53,11 @@ type {{classname}}Service service
 {{#operation}}
 
 type {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request struct {
-	ctx _context.Context
-	ApiService {{#generateInterfaces}}{{classname}}{{/generateInterfaces}}{{^generateInterfaces}}*{{classname}}Service{{/generateInterfaces}}
+	ctx context.Context{{#generateInterfaces}}
+	ApiService {{classname}}
+{{/generateInterfaces}}{{^generateInterfaces}}
+	ApiService *{{classname}}Service
+{{/generateInterfaces}}
 {{#allParams}}
 	{{paramName}} {{^isPathParam}}*{{/isPathParam}}{{{dataType}}}
 {{/allParams}}
@@ -71,7 +74,7 @@ func (r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Reques
 	return r
 }{{/isPathParam}}{{/allParams}}
 
-func (r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request) Execute() ({{#returnType}}{{{.}}}, {{/returnType}}*_nethttp.Response, error) {
+func (r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request) Execute() ({{#returnType}}{{^isArray}}{{^returnTypeIsPrimitive}}*{{/returnTypeIsPrimitive}}{{/isArray}}{{{.}}}, {{/returnType}}*http.Response, error) {
 	return r.ApiService.{{nickname}}Execute(r)
 }
 
@@ -82,15 +85,15 @@ func (r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Reques
 {{{unescapedNotes}}}
 {{/notes}}
 
- @param ctx _context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().{{#pathParams}}
+ @param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().{{#pathParams}}
  @param {{paramName}}{{#description}} {{{.}}}{{/description}}{{/pathParams}}
  @return {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request
 {{#isDeprecated}}
 
 Deprecated
 {{/isDeprecated}}
 */
-func (a *{{{classname}}}Service) {{{nickname}}}(ctx _context.Context{{#pathParams}}, {{paramName}} {{{dataType}}}{{/pathParams}}) {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request {
+func (a *{{{classname}}}Service) {{{nickname}}}(ctx context.Context{{#pathParams}}, {{paramName}} {{{dataType}}}{{/pathParams}}) {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request {
 	return {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request{
 		ApiService: a,
 		ctx: ctx,
@@ -105,27 +108,27 @@ func (a *{{{classname}}}Service) {{{nickname}}}(ctx _context.Context{{#pathParam
 {{#isDeprecated}}
 // Deprecated
 {{/isDeprecated}}
-func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request) ({{#returnType}}{{{.}}}, {{/returnType}}*_nethttp.Response, error) {
+func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&classname}}{{/structPrefix}}Api{{operationId}}Request) ({{#returnType}}{{^isArray}}{{^returnTypeIsPrimitive}}*{{/returnTypeIsPrimitive}}{{/isArray}}{{{.}}}, {{/returnType}}*http.Response, error) {
 	var (
-		localVarHTTPMethod   = _nethttp.Method{{httpMethod}}
+		localVarHTTPMethod   = http.Method{{httpMethod}}
 		localVarPostBody     interface{}
 		formFiles            []formFile
 		{{#returnType}}
-		localVarReturnValue  {{{.}}}
+		localVarReturnValue  {{^isArray}}{{^returnTypeIsPrimitive}}*{{/returnTypeIsPrimitive}}{{/isArray}}{{{.}}}
 		{{/returnType}}
 	)
 
 	localBasePath, err := a.client.cfg.ServerURLWithContext(r.ctx, "{{{classname}}}Service.{{{nickname}}}")
 	if err != nil {
-		return {{#returnType}}localVarReturnValue, {{/returnType}}nil, GenericOpenAPIError{error: err.Error()}
+		return {{#returnType}}localVarReturnValue, {{/returnType}}nil, &GenericOpenAPIError{error: err.Error()}
 	}
 
 	localVarPath := localBasePath + "{{{path}}}"{{#pathParams}}
-	localVarPath = strings.Replace(localVarPath, "{"+"{{baseName}}"+"}", _neturl.PathEscape(parameterToString(r.{{paramName}}, "{{collectionFormat}}")), -1){{/pathParams}}
+	localVarPath = strings.Replace(localVarPath, "{"+"{{baseName}}"+"}", url.PathEscape(parameterToString(r.{{paramName}}, "{{collectionFormat}}")), -1){{/pathParams}}
 
 	localVarHeaderParams := make(map[string]string)
-	localVarQueryParams := _neturl.Values{}
-	localVarFormParams := _neturl.Values{}
+	localVarQueryParams := url.Values{}
+	localVarFormParams := url.Values{}
 	{{#allParams}}
 	{{#required}}
 	{{^isPathParam}}
@@ -265,7 +268,7 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 	}
 {{/required}}
 	if {{paramName}}LocalVarFile != nil {
-		fbs, _ := _ioutil.ReadAll({{paramName}}LocalVarFile)
+		fbs, _ := ioutil.ReadAll({{paramName}}LocalVarFile)
 		{{paramName}}LocalVarFileBytes = fbs
 		{{paramName}}LocalVarFileName = {{paramName}}LocalVarFile.Name()
 		{{paramName}}LocalVarFile.Close()
@@ -344,15 +347,15 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 		return {{#returnType}}localVarReturnValue, {{/returnType}}localVarHTTPResponse, err
 	}
 
-	localVarBody, err := _ioutil.ReadAll(localVarHTTPResponse.Body)
+	localVarBody, err := ioutil.ReadAll(localVarHTTPResponse.Body)
 	localVarHTTPResponse.Body.Close()
-	localVarHTTPResponse.Body = _ioutil.NopCloser(bytes.NewBuffer(localVarBody))
+	localVarHTTPResponse.Body = ioutil.NopCloser(bytes.NewBuffer(localVarBody))
 	if err != nil {
 		return {{#returnType}}localVarReturnValue, {{/returnType}}localVarHTTPResponse, err
 	}
 
 	if localVarHTTPResponse.StatusCode >= 300 {
-		newErr := GenericOpenAPIError{
+		newErr := &GenericOpenAPIError{
 			body:  localVarBody,
 			error: localVarHTTPResponse.Status,
 		}
@@ -399,7 +402,7 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 	{{#returnType}}
 	err = a.client.decode(&localVarReturnValue, localVarBody, localVarHTTPResponse.Header.Get("Content-Type"))
 	if err != nil {
-		newErr := GenericOpenAPIError{
+		newErr := &GenericOpenAPIError{
 			body:  localVarBody,
 			error: err.Error(),
 		}

modules/openapi-generator/src/main/resources/go/api_doc.mustache

@@ -41,8 +41,8 @@ func main() {
     {{/allParams}}
 
     configuration := {{goImportAlias}}.NewConfiguration()
-    api_client := {{goImportAlias}}.NewAPIClient(configuration)
-    resp, r, err := api_client.{{classname}}.{{operationId}}(context.Background(){{#pathParams}}, {{paramName}}{{/pathParams}}){{#allParams}}{{^isPathParam}}.{{vendorExtensions.x-export-param-name}}({{paramName}}){{/isPathParam}}{{/allParams}}.Execute()
+    apiClient := {{goImportAlias}}.NewAPIClient(configuration)
+    resp, r, err := apiClient.{{classname}}.{{operationId}}(context.Background(){{#pathParams}}, {{paramName}}{{/pathParams}}){{#allParams}}{{^isPathParam}}.{{vendorExtensions.x-export-param-name}}({{paramName}}){{/isPathParam}}{{/allParams}}.Execute()
     if err != nil {
         fmt.Fprintf(os.Stderr, "Error when calling `{{classname}}.{{operationId}}``: %v\n", err)
         fmt.Fprintf(os.Stderr, "Full HTTP response: %v\n", r)

modules/openapi-generator/src/main/resources/go/client.mustache

@@ -477,6 +477,13 @@ func reportError(format string, a ...interface{}) error {
 	return fmt.Errorf(format, a...)
 }
 
+// A wrapper for strict JSON decoding
+func newStrictDecoder(data []byte) *json.Decoder {
+	dec := json.NewDecoder(bytes.NewBuffer(data))
+	dec.DisallowUnknownFields()
+	return dec
+}
+
 // Set request body from an interface{}
 func setBody(body interface{}, contentType string) (bodyBuf *bytes.Buffer, err error) {
 	if bodyBuf == nil {

modules/openapi-generator/src/main/resources/go/go.mod.mustache

@@ -3,7 +3,7 @@ module {{gitHost}}/{{gitUserId}}/{{gitRepoId}}{{#isGoSubmodule}}/{{packageName}}
 go 1.13
 
 require (
-	golang.org/x/oauth2 v0.0.0-20210218202405-ba52d332ba99
+	golang.org/x/oauth2 v0.0.0-20210323180902-22b0adad7558
 	{{#withAWSV4Signature}}
 	github.com/aws/aws-sdk-go v1.34.14
 	{{/withAWSV4Signature}}

modules/openapi-generator/src/main/resources/go/model_oneof.mustache

@@ -1,14 +1,16 @@
 // {{classname}} - {{{description}}}{{^description}}struct for {{{classname}}}{{/description}}
 type {{classname}} struct {
 	{{#oneOf}}
-	{{{.}}} *{{{.}}}
+	{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}} *{{{.}}}
 	{{/oneOf}}
 }
 
 {{#oneOf}}
 // {{{.}}}As{{classname}} is a convenience function that returns {{{.}}} wrapped in {{classname}}
-func {{{.}}}As{{classname}}(v *{{{.}}}) {{classname}} {
-	return {{classname}}{ {{{.}}}: v}
+func {{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}}As{{classname}}(v *{{{.}}}) {{classname}} {
+	return {{classname}}{
+		{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}}: v,
+	}
 }
 
 {{/oneOf}}
@@ -29,7 +31,7 @@ func (dst *{{classname}}) UnmarshalJSON(data []byte) error {
 	{{#-first}}
 	// use discriminator value to speed up the lookup
 	var jsonDict map[string]interface{}
-	err = json.Unmarshal(data, &jsonDict)
+	err = newStrictDecoder(data).Decode(&jsonDict)
 	if err != nil {
 		return fmt.Errorf("Failed to unmarshal JSON into map for the discriminator lookup.")
 	}
@@ -84,24 +86,24 @@ func (dst *{{classname}}) UnmarshalJSON(data []byte) error {
 	{{^useOneOfDiscriminatorLookup}}
 	match := 0
 	{{#oneOf}}
-	// try to unmarshal data into {{{.}}}
-	err = json.Unmarshal(data, &dst.{{{.}}})
+	// try to unmarshal data into {{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}}
+	err = newStrictDecoder(data).Decode(&dst.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}})
 	if err == nil {
-		json{{{.}}}, _ := json.Marshal(dst.{{{.}}})
-		if string(json{{{.}}}) == "{}" { // empty struct
-			dst.{{{.}}} = nil
+		json{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}}, _ := json.Marshal(dst.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}})
+		if string(json{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}}) == "{}" { // empty struct
+			dst.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}} = nil
 		} else {
 			match++
 		}
 	} else {
-		dst.{{{.}}} = nil
+		dst.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}} = nil
 	}
 
 	{{/oneOf}}
 	if match > 1 { // more than 1 match
 		// reset to nil
 		{{#oneOf}}
-		dst.{{{.}}} = nil
+		dst.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}} = nil
 		{{/oneOf}}
 
 		return fmt.Errorf("Data matches more than one schema in oneOf({{classname}})")
@@ -116,8 +118,8 @@ func (dst *{{classname}}) UnmarshalJSON(data []byte) error {
 // Marshal data from the first non-nil pointers in the struct to JSON
 func (src {{classname}}) MarshalJSON() ([]byte, error) {
 {{#oneOf}}
-	if src.{{{.}}} != nil {
-		return json.Marshal(&src.{{{.}}})
+	if src.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}} != nil {
+		return json.Marshal(&src.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}})
 	}
 
 {{/oneOf}}
@@ -126,9 +128,12 @@ func (src {{classname}}) MarshalJSON() ([]byte, error) {
 
 // Get the actual instance
 func (obj *{{classname}}) GetActualInstance() (interface{}) {
+	if obj == nil {
+		return nil
+	}
 {{#oneOf}}
-	if obj.{{{.}}} != nil {
-		return obj.{{{.}}}
+	if obj.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}} != nil {
+		return obj.{{#lambda.titlecase}}{{{.}}}{{/lambda.titlecase}}
 	}
 
 {{/oneOf}}