FIX #21407 - use referenced string enum schema in requestBody if available

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

@@ -397,6 +397,9 @@ public static enum ENUM_PROPERTY_NAMING_TYPE {camelCase, PascalCase, snake_case,
     public static final String REMOVE_ENUM_VALUE_PREFIX = "removeEnumValuePrefix";
     public static final String REMOVE_ENUM_VALUE_PREFIX_DESC = "Remove the common prefix of enum values";
 
+    public static final String USE_STRING_ENUM_SCHEMA_REF_FOR_REQUEST_BODY = "useStringEnumSchemaRefForRequestBody";
+    public static final String USE_STRING_ENUM_SCHEMA_REF_FOR_REQUEST_BODY_DESC = "A boolean flag that controls how the parameter type for a referenced string enum in a request body is generated. When set to true, the generator will use the referenced schema instead of a plain String type";
+
     public static final String SKIP_ONEOF_ANYOF_GETTER = "skipOneOfAnyOfGetter";
     public static final String SKIP_ONEOF_ANYOF_GETTER_DESC = "Skip the generation of getter for sub-schemas in oneOf/anyOf models.";
 

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

@@ -7794,8 +7794,13 @@ protected void updateRequestBodyForArray(CodegenParameter codegenParameter, Sche
         }
     }
 
-    protected void updateRequestBodyForString(CodegenParameter codegenParameter, Schema schema, Set<String> imports, String bodyParameterName) {
-        updateRequestBodyForPrimitiveType(codegenParameter, schema, bodyParameterName, imports);
+    protected void updateRequestBodyForString(CodegenParameter codegenParameter, Schema schema, String name, Set<String> imports, String bodyParameterName) {
+        if (convertPropertyToBoolean(CodegenConstants.USE_STRING_ENUM_SCHEMA_REF_FOR_REQUEST_BODY) && !StringUtils.isEmpty(name)) {
+            addBodyModelSchema(codegenParameter, name, schema, imports, bodyParameterName, false);
+        } else {
+            updateRequestBodyForPrimitiveType(codegenParameter, schema, bodyParameterName, imports);
+        }
+
         if (ModelUtils.isByteArraySchema(schema)) {
             codegenParameter.setIsString(false);
             codegenParameter.isByteArray = true;
@@ -7996,7 +8001,7 @@ public CodegenParameter fromRequestBody(RequestBody body, Set<String> imports, S
             // swagger v2 only, type file
             codegenParameter.isFile = true;
         } else if (ModelUtils.isStringSchema(schema)) {
-            updateRequestBodyForString(codegenParameter, schema, imports, bodyParameterName);
+            updateRequestBodyForString(codegenParameter, schema, name, imports, bodyParameterName);
         } else if (ModelUtils.isNumberSchema(schema)) {
             updateRequestBodyForPrimitiveType(codegenParameter, schema, bodyParameterName, imports);
             codegenParameter.isNumeric = Boolean.TRUE;

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

@@ -48,6 +48,7 @@
 import org.openapitools.codegen.utils.SemVer;
 import org.slf4j.LoggerFactory;
 import org.testng.Assert;
+import org.testng.annotations.DataProvider;
 import org.testng.annotations.Ignore;
 import org.testng.annotations.Test;
 
@@ -5015,4 +5016,49 @@ public void testSingleRequestParameter_hasSingleParamTrue() {
         // When & Then
         assertThat(codegenOperation.getHasSingleParam()).isTrue();
     }
+
+    @DataProvider(name = "testRequestBodyWithStringEnumSchemaData")
+    private Object[][] testRequestBodyWithStringEnumSchemaData() {
+        return new Object[][]{
+                {false, "String"},
+                {true, "Letter"}
+        };
+    }
+
+    @Test(dataProvider = "testRequestBodyWithStringEnumSchemaData")
+    public void testRequestBodyWithStringEnumSchema(boolean useStringEnumSchemaRefForRequestBody, String expectedDataType) {
+        // Given
+        OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/issue_21407.yaml");
+        DefaultCodegen codegen = new DefaultCodegen();
+        codegen.setOpenAPI(openAPI);
+        codegen.additionalProperties().put(CodegenConstants.USE_STRING_ENUM_SCHEMA_REF_FOR_REQUEST_BODY, useStringEnumSchemaRefForRequestBody);
+        String path = "/v1/resource-class/send-using-schema";
+
+        // When
+        CodegenOperation codegenOperation = codegen.fromOperation(path, "POST", openAPI.getPaths().get(path).getPost(), null);
+
+        // Then
+        assertThat(codegenOperation.bodyParam).satisfies(bodyParam -> {
+            assertThat(bodyParam).isNotNull();
+            assertThat(bodyParam.getDataType()).isEqualTo(expectedDataType);
+        });
+    }
+
+    @Test
+    public void testRequestBodyWithStringSchema() {
+        // Given
+        OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/issue_21407.yaml");
+        DefaultCodegen codegen = new DefaultCodegen();
+        codegen.setOpenAPI(openAPI);
+        String path = "/v1/resource-class/send-using-string";
+
+        // When
+        CodegenOperation codegenOperation = codegen.fromOperation(path, "POST", openAPI.getPaths().get(path).getPost(), null);
+
+        // Then
+        assertThat(codegenOperation.bodyParam).satisfies(bodyParam -> {
+            assertThat(bodyParam).isNotNull();
+            assertThat(bodyParam.getDataType()).isEqualTo("String");
+        });
+    }
 }

modules/openapi-generator/src/test/resources/3_0/issue_21407.yaml

@@ -0,0 +1,48 @@
+openapi: 3.0.1
+info:
+  title: sample spec
+  description: "Sample spec"
+  version: 0.0.1
+tags:
+- name: ResourceClass
+paths:
+  /v1/resource-class/send-using-schema:
+    post:
+      tags:
+      - ResourceClass
+      description: Add @Operation annotation to provide a description
+      operationId: send-using-schema
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/Letter"
+      responses:
+        "200":
+          description: OK - the request has succeeded.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Letter"
+  /v1/resource-class/send-using-string:
+    post:
+      tags:
+        - ResourceClass
+      description: Add @Operation annotation to provide a description
+      operationId: send-using-string
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: string
+      responses:
+        "204":
+          description: "No Content - the request has been successfully processed,\
+            \ but there is no additional content."
+components:
+  schemas:
+    Letter:
+      type: string
+      enum:
+      - A
+      - B