fix(go-server): use operationId consistently to fix uncompilable output for duplicate operationIds

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

@@ -15,7 +15,7 @@ type {{classname}} struct {
 {{#isDeprecated}}
 // Deprecated
 {{/isDeprecated}}
-func (api *{{classname}}) {{nickname}}(c *gin.Context) {
+func (api *{{classname}}) {{operationId}}(c *gin.Context) {
 	// Your handler implementation
 	c.JSON(200, gin.H{"status": "OK"})
 }

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

@@ -10,12 +10,12 @@ type {{classname}} interface {
 
 
     {{#operation}}
-    // {{nickname}} {{httpMethod}} {{{basePathWithoutHost}}}{{{path}}}{{#summary}}
+    // {{operationId}} {{httpMethod}} {{{basePathWithoutHost}}}{{{path}}}{{#summary}}
     // {{{.}}} {{/summary}}
     {{#isDeprecated}}
     // Deprecated
     {{/isDeprecated}}
-     {{nickname}}(c *gin.Context)
+     {{operationId}}(c *gin.Context)
 
     {{/operation}}
     {{/operations}}

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

@@ -92,11 +92,11 @@ func (c *{{classname}}Controller) OrderedRoutes() []Route {
 
 {{#operations}}{{#operation}}
 
-// {{nickname}} - {{{summary}}}
+// {{operationId}} - {{{summary}}}
 {{#isDeprecated}}
 // Deprecated
 {{/isDeprecated}}
-func (c *{{classname}}Controller) {{nickname}}(w http.ResponseWriter, r *http.Request) {
+func (c *{{classname}}Controller) {{operationId}}(w http.ResponseWriter, r *http.Request) {
 	{{#hasFormParams}}
 	{{#isMultipart}}
 	if err := r.ParseMultipartForm(32 << 20); err != nil {
@@ -641,7 +641,7 @@ func (c *{{classname}}Controller) {{nickname}}(w http.ResponseWriter, r *http.Re
 	{{/isArray}}
 	{{/isBodyParam}}
 	{{/allParams}}
-	result, err := c.service.{{nickname}}(r.Context(){{#allParams}}, {{#isNullable}}{{#isBodyParam}}&{{/isBodyParam}}{{/isNullable}}{{paramName}}Param{{/allParams}})
+	result, err := c.service.{{operationId}}(r.Context(){{#allParams}}, {{#isNullable}}{{#isBodyParam}}&{{/isBodyParam}}{{/isNullable}}{{paramName}}Param{{/allParams}})
 	// If an error occurred, encode the error with the status code
 	if err != nil {
 		c.errorHandler(w, r, err, &result)

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

@@ -19,12 +19,12 @@ func New{{classname}}Service() *{{classname}}Service {
 	return &{{classname}}Service{}
 }{{#operations}}{{#operation}}
 
-// {{nickname}} - {{summary}}
+// {{operationId}} - {{summary}}
 {{#isDeprecated}}
 // Deprecated
 {{/isDeprecated}}
-func (s *{{classname}}Service) {{nickname}}(ctx context.Context{{#allParams}}, {{paramName}} {{#isNullable}}*{{/isNullable}}{{dataType}}{{/allParams}}) (ImplResponse, error) {
-	// TODO - update {{nickname}} with the required logic for this service method.
+func (s *{{classname}}Service) {{operationId}}(ctx context.Context{{#allParams}}, {{paramName}} {{#isNullable}}*{{/isNullable}}{{dataType}}{{/allParams}}) (ImplResponse, error) {
+	// TODO - update {{operationId}} with the required logic for this service method.
 	// Add {{classFilename}}_service.go to the .openapi-generator-ignore to avoid overwriting this service implementation when updating open api generation.
 
 {{#responses}}
@@ -39,5 +39,5 @@ func (s *{{classname}}Service) {{nickname}}(ctx context.Context{{#allParams}}, {
 
 {{/dataType}}
 {{/responses}}
-	return Response(http.StatusNotImplemented, nil), errors.New("{{nickname}} method not implemented")
+	return Response(http.StatusNotImplemented, nil), errors.New("{{operationId}} method not implemented")
 }{{/operation}}{{/operations}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/goginserver/GoGinServerCodegenTest.java

@@ -20,10 +20,12 @@
 import org.openapitools.codegen.DefaultGenerator;
 import org.openapitools.codegen.TestUtils;
 import org.openapitools.codegen.config.CodegenConfigurator;
+import org.testng.Assert;
 import org.testng.annotations.Test;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.List;
@@ -85,6 +87,42 @@ public void verifyInterfaceOnly() throws IOException {
                 "type PetAPI interface");
     }
 
+    @Test
+    public void verifyDuplicateOperationIdsAreConsistent() throws IOException {
+        // Regression test for duplicate auto-generated operationIds (e.g. /foo and /foo/).
+        // go-gin-server's routers.mustache references handleFunctions.<Class>.{{operationId}}
+        // while interface-api.mustache/controller-api.mustache used to declare the method
+        // with {{nickname}}. nickname and operationId were deduplicated by two independent
+        // passes with inconsistent counter conventions (_1 vs _0), so routers referenced
+        // FooGet_0 while the handler/interface declared FooGet_1, producing uncompilable
+        // code. The fix makes those templates use {{operationId}} consistently.
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = createDefaultCodegenConfigurator(output)
+                .setInputSpec("src/test/resources/3_0/go-gin-server/duplicate-operation-ids.yaml");
+
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(configurator.toClientOptInput()).generate();
+        files.forEach(File::deleteOnExit);
+
+        // routers.go uses {{operationId}} to reference the handler method on the generated struct.
+        TestUtils.assertFileContains(Paths.get(output + "/go/routers.go"),
+                "handleFunctions.DefaultAPI.FooGet_0");
+        // controller-api.mustache now uses {{operationId}} for the handler method, matching
+        // the {{operationId}} reference in routers.go.
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default.go"),
+                "func (api *DefaultAPI) FooGet_0(");
+
+        // Negative assertion: the divergent _1 name must not appear anywhere.
+        String routers = new String(Files.readAllBytes(Paths.get(output + "/go/routers.go")), StandardCharsets.UTF_8);
+        String apiDefault = new String(Files.readAllBytes(Paths.get(output + "/go/api_default.go")), StandardCharsets.UTF_8);
+        Assert.assertFalse(routers.contains("FooGet_1"),
+                "nickname diverged from operationId (FooGet_1 present in routers.go)");
+        Assert.assertFalse(apiDefault.contains("FooGet_1"),
+                "nickname diverged from operationId (FooGet_1 present in api_default.go)");
+    }
+
     private static CodegenConfigurator createDefaultCodegenConfigurator(File output) {
         return new CodegenConfigurator()
                 .setGeneratorName("go-gin-server")

modules/openapi-generator/src/test/java/org/openapitools/codegen/goserver/GoServerCodegenTest.java

@@ -25,6 +25,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.List;
@@ -74,6 +75,58 @@ public void verifyOrder() throws IOException {
 
     }
 
+    @Test
+    public void verifyDuplicateOperationIdsAreConsistent() throws IOException {
+        // Regression test for duplicate auto-generated operationIds (e.g. /foo and /foo/).
+        // Previously nickname and operationId were deduplicated by two independent passes with
+        // inconsistent counter conventions (_1 vs _0), so the route map / interfaces used
+        // {{operationId}} (e.g. FooGet_0) while the controller handler / service stub used
+        // {{nickname}} (e.g. FooGet_1), producing uncompilable code.
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = createDefaultCodegenConfigurator(output)
+                .setInputSpec("src/test/resources/3_0/go-server/duplicate-operation-ids.yaml");
+
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(configurator.toClientOptInput()).generate();
+        files.forEach(File::deleteOnExit);
+
+        // The deduplicated operationId pair is FooGet and FooGet_0; routes, handlers and
+        // service stubs must all reference the same name (templates use {{operationId}}).
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default.go"),
+                "\"FooGet\": Route{");
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default.go"),
+                "\"FooGet_0\": Route{");
+
+        // Route handler reference (uses {{operationId}}) and handler method definition
+        // (uses {{nickname}}) must reference the same name.
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default.go"),
+                "c.FooGet_0,");
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default.go"),
+                "func (c *DefaultAPIController) FooGet_0(");
+        // Service call inside the handler must also use the deduplicated operationId.
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default.go"),
+                "c.service.FooGet_0(");
+
+        // The interface (api.go) and the service stub must declare FooGet_0 too.
+        TestUtils.assertFileContains(Paths.get(output + "/go/api.go"),
+                "FooGet_0(");
+        TestUtils.assertFileContains(Paths.get(output + "/go/api_default_service.go"),
+                "func (s *DefaultAPIService) FooGet_0(");
+
+        // Negative assertions: the divergent _1 name must not appear anywhere.
+        String apiDefault = new String(Files.readAllBytes(Paths.get(output + "/go/api_default.go")), StandardCharsets.UTF_8);
+        String api = new String(Files.readAllBytes(Paths.get(output + "/go/api.go")), StandardCharsets.UTF_8);
+        String apiService = new String(Files.readAllBytes(Paths.get(output + "/go/api_default_service.go")), StandardCharsets.UTF_8);
+        Assert.assertFalse(apiDefault.contains("FooGet_1"),
+                "nickname diverged from operationId (FooGet_1 present in api_default.go)");
+        Assert.assertFalse(api.contains("FooGet_1"),
+                "nickname diverged from operationId (FooGet_1 present in api.go)");
+        Assert.assertFalse(apiService.contains("FooGet_1"),
+                "nickname diverged from operationId (FooGet_1 present in api_default_service.go)");
+    }
+
     private static CodegenConfigurator createDefaultCodegenConfigurator(File output) {
         return new CodegenConfigurator()
                 .setGeneratorName("go-server")

modules/openapi-generator/src/test/resources/3_0/go-gin-server/duplicate-operation-ids.yaml

@@ -0,0 +1,21 @@
+openapi: 3.0.1
+
+info:
+  version: 1.0.0
+  title: Duplicate auto-generated operationIds
+
+paths:
+  /foo:
+    get:
+      tags:
+        - default
+      responses:
+        '200':
+          description: ok
+  /foo/:
+    get:
+      tags:
+        - default
+      responses:
+        '200':
+          description: ok

modules/openapi-generator/src/test/resources/3_0/go-server/duplicate-operation-ids.yaml

@@ -0,0 +1,21 @@
+openapi: 3.0.1
+
+info:
+  version: 1.0.0
+  title: Duplicate auto-generated operationIds
+
+paths:
+  /foo:
+    get:
+      tags:
+        - default
+      responses:
+        '200':
+          description: ok
+  /foo/:
+    get:
+      tags:
+        - default
+      responses:
+        '200':
+          description: ok