diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
index e66f40d55342..cef79bf56abd 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
@@ -1382,6 +1382,7 @@ public ExtendedCodegenProperty(CodegenProperty cp) {
             this.xmlName = cp.xmlName;
             this.xmlNamespace = cp.xmlNamespace;
             this.isXmlWrapped = cp.isXmlWrapped;
+            this.setHasSanitizedName(cp.getHasSanitizedName());
         }
 
         @Override
diff --git a/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache b/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
index 76de06732fd3..cfebd1f9d40a 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
@@ -25,7 +25,28 @@ import { type {{modelName}}, {{modelName}}FromJSONTyped, {{modelName}}ToJSON, {{
 export function instanceOf{{classname}}(value: object): value is {{classname}} {
     {{#vars}}
     {{#required}}
+    {{#hasSanitizedName}}
+    if ((!('{{name}}' in value) && !('{{baseName}}' in value)) || (value['{{name}}'] === undefined && value['{{baseName}}'] === undefined)) return false;
+    {{/hasSanitizedName}}
+    {{^hasSanitizedName}}
     if (!('{{name}}' in value) || value['{{name}}'] === undefined) return false;
+    {{/hasSanitizedName}}
+    {{#isEnum}}
+    {{#allowableValues}}
+    {{#values}}
+    {{#-first}}
+    {{#-last}}
+    {{#hasSanitizedName}}
+    if (value['{{name}}'] !== '{{.}}' && value['{{baseName}}'] !== '{{.}}') return false;
+    {{/hasSanitizedName}}
+    {{^hasSanitizedName}}
+    if (value['{{name}}'] !== '{{.}}') return false;
+    {{/hasSanitizedName}}
+    {{/-last}}
+    {{/-first}}
+    {{/values}}
+    {{/allowableValues}}
+    {{/isEnum}}
     {{/required}}
     {{/vars}}
     return true;
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientCodegenTest.java
index da183535f3ad..4c6965d97b6a 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientCodegenTest.java
@@ -445,6 +445,48 @@ public void testOneOfModelsImportNonPrimitiveTypes() throws IOException {
         TestUtils.assertFileContains(testResponse, "import type { OptionThree } from './OptionThree'");
     }
 
+    @Test(description = "Verify instanceOf checks discriminator value for single-value enums")
+    public void testInstanceOfChecksDiscriminatorValue() throws IOException {
+        File output = generate(Collections.emptyMap(), "src/test/resources/3_0/typescript-fetch/oneOf.yaml");
+
+        // OptionOne should check discriminator value
+        Path optionOne = Paths.get(output + "/models/OptionOne.ts");
+        TestUtils.assertFileExists(optionOne);
+        TestUtils.assertFileContains(optionOne, "value['discriminatorField'] !== 'optionOne'");
+
+        // OptionTwo should check discriminator value
+        Path optionTwo = Paths.get(output + "/models/OptionTwo.ts");
+        TestUtils.assertFileExists(optionTwo);
+        TestUtils.assertFileContains(optionTwo, "value['discriminatorField'] !== 'optionTwo'");
+
+        // TestA should NOT have a value check (foo is a plain string, not a single-value enum)
+        Path testA = Paths.get(output + "/models/TestA.ts");
+        TestUtils.assertFileExists(testA);
+        TestUtils.assertFileNotContains(testA, "value['foo'] !==");
+
+        // SnakeOptionOne: discriminator_field (snake_case baseName) vs discriminatorField (camelCase name)
+        // instanceOf should check both casings for field presence and discriminator value
+        Path snakeOptionOne = Paths.get(output + "/models/SnakeOptionOne.ts");
+        TestUtils.assertFileExists(snakeOptionOne);
+        TestUtils.assertFileContains(snakeOptionOne, "'discriminatorField' in value");
+        TestUtils.assertFileContains(snakeOptionOne, "'discriminator_field' in value");
+        TestUtils.assertFileContains(snakeOptionOne, "value['discriminatorField'] !== 'snakeOptionOne'");
+        TestUtils.assertFileContains(snakeOptionOne, "value['discriminator_field'] !== 'snakeOptionOne'");
+        // Also verify the non-enum required field checks both casings
+        TestUtils.assertFileContains(snakeOptionOne, "'someProperty' in value");
+        TestUtils.assertFileContains(snakeOptionOne, "'some_property' in value");
+
+        // DashedOptionOne: discriminator-field (dashed baseName) vs discriminatorField (camelCase name)
+        Path dashedOptionOne = Paths.get(output + "/models/DashedOptionOne.ts");
+        TestUtils.assertFileExists(dashedOptionOne);
+        TestUtils.assertFileContains(dashedOptionOne, "'discriminatorField' in value");
+        TestUtils.assertFileContains(dashedOptionOne, "'discriminator-field' in value");
+        TestUtils.assertFileContains(dashedOptionOne, "value['discriminatorField'] !== 'dashedOptionOne'");
+        TestUtils.assertFileContains(dashedOptionOne, "value['discriminator-field'] !== 'dashedOptionOne'");
+        TestUtils.assertFileContains(dashedOptionOne, "'someProperty' in value");
+        TestUtils.assertFileContains(dashedOptionOne, "'some-property' in value");
+    }
+
     @Test(description = "Verify validationAttributes works with withoutRuntimeChecks=true")
     public void testValidationAttributesWithWithoutRuntimeChecks() throws IOException {
         Map<String, Object> properties = new HashMap<>();
diff --git a/modules/openapi-generator/src/test/resources/3_0/typescript-fetch/oneOf.yaml b/modules/openapi-generator/src/test/resources/3_0/typescript-fetch/oneOf.yaml
index 958b601804dc..4bc0acc424eb 100644
--- a/modules/openapi-generator/src/test/resources/3_0/typescript-fetch/oneOf.yaml
+++ b/modules/openapi-generator/src/test/resources/3_0/typescript-fetch/oneOf.yaml
@@ -35,6 +35,26 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/TestDiscriminatorResponse'
+  /test-snake-case-discriminator:
+    get:
+      operationId: testSnakeCaseDiscriminator
+      responses:
+        200:
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TestSnakeCaseDiscriminatorResponse'
+  /test-dashed-discriminator:
+    get:
+      operationId: testDashedDiscriminator
+      responses:
+        200:
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TestDashedDiscriminatorResponse'
 components:
   schemas:
     TestArrayResponse:
@@ -93,4 +113,70 @@ components:
             - "optionTwo"
           type: string
       required:
-        - discriminatorField
\ No newline at end of file
+        - discriminatorField
+    TestSnakeCaseDiscriminatorResponse:
+      discriminator:
+        propertyName: discriminator_field
+        mapping:
+          snakeOptionOne: "#/components/schemas/SnakeOptionOne"
+          snakeOptionTwo: "#/components/schemas/SnakeOptionTwo"
+      oneOf:
+        - $ref: "#/components/schemas/SnakeOptionOne"
+        - $ref: "#/components/schemas/SnakeOptionTwo"
+    SnakeOptionOne:
+      type: object
+      properties:
+        discriminator_field:
+          enum:
+            - "snakeOptionOne"
+          type: string
+        some_property:
+          type: string
+      required:
+        - discriminator_field
+        - some_property
+    SnakeOptionTwo:
+      type: object
+      properties:
+        discriminator_field:
+          enum:
+            - "snakeOptionTwo"
+          type: string
+        some_property:
+          type: string
+      required:
+        - discriminator_field
+        - some_property
+    TestDashedDiscriminatorResponse:
+      discriminator:
+        propertyName: discriminator-field
+        mapping:
+          dashedOptionOne: "#/components/schemas/DashedOptionOne"
+          dashedOptionTwo: "#/components/schemas/DashedOptionTwo"
+      oneOf:
+        - $ref: "#/components/schemas/DashedOptionOne"
+        - $ref: "#/components/schemas/DashedOptionTwo"
+    DashedOptionOne:
+      type: object
+      properties:
+        discriminator-field:
+          enum:
+            - "dashedOptionOne"
+          type: string
+        some-property:
+          type: string
+      required:
+        - discriminator-field
+        - some-property
+    DashedOptionTwo:
+      type: object
+      properties:
+        discriminator-field:
+          enum:
+            - "dashedOptionTwo"
+          type: string
+        some-property:
+          type: string
+      required:
+        - discriminator-field
+        - some-property
\ No newline at end of file
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/EnumTest.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/EnumTest.ts
index a5eecc180343..6890904e62b9 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/EnumTest.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/EnumTest.ts
@@ -142,7 +142,7 @@ export type EnumTestEnumNumberEnum = typeof EnumTestEnumNumberEnum[keyof typeof
  * Check if a given object implements the EnumTest interface.
  */
 export function instanceOfEnumTest(value: object): value is EnumTest {
-    if (!('enumStringRequired' in value) || value['enumStringRequired'] === undefined) return false;
+    if ((!('enumStringRequired' in value) && !('enum_string_required' in value)) || (value['enumStringRequired'] === undefined && value['enum_string_required'] === undefined)) return false;
     return true;
 }
 
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/FormatTest.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/FormatTest.ts
index f695e974f39d..822bb60636fb 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/FormatTest.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/models/FormatTest.ts
@@ -122,7 +122,7 @@ export interface FormatTest {
  */
 export function instanceOfFormatTest(value: object): value is FormatTest {
     if (!('number' in value) || value['number'] === undefined) return false;
-    if (!('_byte' in value) || value['_byte'] === undefined) return false;
+    if ((!('_byte' in value) && !('byte' in value)) || (value['_byte'] === undefined && value['byte'] === undefined)) return false;
     if (!('date' in value) || value['date'] === undefined) return false;
     if (!('password' in value) || value['password'] === undefined) return false;
     return true;
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/.openapi-generator/FILES b/samples/client/petstore/typescript-fetch/builds/oneOf/.openapi-generator/FILES
index 20834d7a9398..33963b08ced9 100644
--- a/samples/client/petstore/typescript-fetch/builds/oneOf/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/.openapi-generator/FILES
@@ -1,20 +1,32 @@
 apis/DefaultApi.ts
 apis/index.ts
+docs/DashedOptionOne.md
+docs/DashedOptionTwo.md
 docs/DefaultApi.md
 docs/OptionOne.md
 docs/OptionTwo.md
+docs/SnakeOptionOne.md
+docs/SnakeOptionTwo.md
 docs/TestA.md
 docs/TestArrayResponse.md
 docs/TestB.md
+docs/TestDashedDiscriminatorResponse.md
 docs/TestDiscriminatorResponse.md
 docs/TestResponse.md
+docs/TestSnakeCaseDiscriminatorResponse.md
 index.ts
+models/DashedOptionOne.ts
+models/DashedOptionTwo.ts
 models/OptionOne.ts
 models/OptionTwo.ts
+models/SnakeOptionOne.ts
+models/SnakeOptionTwo.ts
 models/TestA.ts
 models/TestArrayResponse.ts
 models/TestB.ts
+models/TestDashedDiscriminatorResponse.ts
 models/TestDiscriminatorResponse.ts
 models/TestResponse.ts
+models/TestSnakeCaseDiscriminatorResponse.ts
 models/index.ts
 runtime.ts
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/apis/DefaultApi.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/apis/DefaultApi.ts
index 725866801ae3..45e25fa7df26 100644
--- a/samples/client/petstore/typescript-fetch/builds/oneOf/apis/DefaultApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/apis/DefaultApi.ts
@@ -16,16 +16,22 @@
 import * as runtime from '../runtime';
 import type {
   TestArrayResponse,
+  TestDashedDiscriminatorResponse,
   TestDiscriminatorResponse,
   TestResponse,
+  TestSnakeCaseDiscriminatorResponse,
 } from '../models/index';
 import {
     TestArrayResponseFromJSON,
     TestArrayResponseToJSON,
+    TestDashedDiscriminatorResponseFromJSON,
+    TestDashedDiscriminatorResponseToJSON,
     TestDiscriminatorResponseFromJSON,
     TestDiscriminatorResponseToJSON,
     TestResponseFromJSON,
     TestResponseToJSON,
+    TestSnakeCaseDiscriminatorResponseFromJSON,
+    TestSnakeCaseDiscriminatorResponseToJSON,
 } from '../models/index';
 
 /**
@@ -103,6 +109,41 @@ export class DefaultApi extends runtime.BaseAPI {
         return await response.value();
     }
 
+    /**
+     * Creates request options for testDashedDiscriminator without sending the request
+     */
+    async testDashedDiscriminatorRequestOpts(): Promise<runtime.RequestOpts> {
+        const queryParameters: any = {};
+
+        const headerParameters: runtime.HTTPHeaders = {};
+
+
+        let urlPath = `/test-dashed-discriminator`;
+
+        return {
+            path: urlPath,
+            method: 'GET',
+            headers: headerParameters,
+            query: queryParameters,
+        };
+    }
+
+    /**
+     */
+    async testDashedDiscriminatorRaw(initOverrides?: RequestInit | runtime.InitOverrideFunction): Promise<runtime.ApiResponse<TestDashedDiscriminatorResponse>> {
+        const requestOptions = await this.testDashedDiscriminatorRequestOpts();
+        const response = await this.request(requestOptions, initOverrides);
+
+        return new runtime.JSONApiResponse(response, (jsonValue) => TestDashedDiscriminatorResponseFromJSON(jsonValue));
+    }
+
+    /**
+     */
+    async testDashedDiscriminator(initOverrides?: RequestInit | runtime.InitOverrideFunction): Promise<TestDashedDiscriminatorResponse> {
+        const response = await this.testDashedDiscriminatorRaw(initOverrides);
+        return await response.value();
+    }
+
     /**
      * Creates request options for testDiscriminator without sending the request
      */
@@ -138,4 +179,39 @@ export class DefaultApi extends runtime.BaseAPI {
         return await response.value();
     }
 
+    /**
+     * Creates request options for testSnakeCaseDiscriminator without sending the request
+     */
+    async testSnakeCaseDiscriminatorRequestOpts(): Promise<runtime.RequestOpts> {
+        const queryParameters: any = {};
+
+        const headerParameters: runtime.HTTPHeaders = {};
+
+
+        let urlPath = `/test-snake-case-discriminator`;
+
+        return {
+            path: urlPath,
+            method: 'GET',
+            headers: headerParameters,
+            query: queryParameters,
+        };
+    }
+
+    /**
+     */
+    async testSnakeCaseDiscriminatorRaw(initOverrides?: RequestInit | runtime.InitOverrideFunction): Promise<runtime.ApiResponse<TestSnakeCaseDiscriminatorResponse>> {
+        const requestOptions = await this.testSnakeCaseDiscriminatorRequestOpts();
+        const response = await this.request(requestOptions, initOverrides);
+
+        return new runtime.JSONApiResponse(response, (jsonValue) => TestSnakeCaseDiscriminatorResponseFromJSON(jsonValue));
+    }
+
+    /**
+     */
+    async testSnakeCaseDiscriminator(initOverrides?: RequestInit | runtime.InitOverrideFunction): Promise<TestSnakeCaseDiscriminatorResponse> {
+        const response = await this.testSnakeCaseDiscriminatorRaw(initOverrides);
+        return await response.value();
+    }
+
 }
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DashedOptionOne.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DashedOptionOne.md
new file mode 100644
index 000000000000..cd9035c6f5f2
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DashedOptionOne.md
@@ -0,0 +1,36 @@
+
+# DashedOptionOne
+
+
+## Properties
+
+Name | Type
+------------ | -------------
+`discriminatorField` | string
+`someProperty` | string
+
+## Example
+
+```typescript
+import type { DashedOptionOne } from ''
+
+// TODO: Update the object below with actual values
+const example = {
+  "discriminatorField": null,
+  "someProperty": null,
+} satisfies DashedOptionOne
+
+console.log(example)
+
+// Convert the instance to a JSON string
+const exampleJSON: string = JSON.stringify(example)
+console.log(exampleJSON)
+
+// Parse the JSON string back to an object
+const exampleParsed = JSON.parse(exampleJSON) as DashedOptionOne
+console.log(exampleParsed)
+```
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DashedOptionTwo.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DashedOptionTwo.md
new file mode 100644
index 000000000000..521205205876
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DashedOptionTwo.md
@@ -0,0 +1,36 @@
+
+# DashedOptionTwo
+
+
+## Properties
+
+Name | Type
+------------ | -------------
+`discriminatorField` | string
+`someProperty` | string
+
+## Example
+
+```typescript
+import type { DashedOptionTwo } from ''
+
+// TODO: Update the object below with actual values
+const example = {
+  "discriminatorField": null,
+  "someProperty": null,
+} satisfies DashedOptionTwo
+
+console.log(example)
+
+// Convert the instance to a JSON string
+const exampleJSON: string = JSON.stringify(example)
+console.log(exampleJSON)
+
+// Parse the JSON string back to an object
+const exampleParsed = JSON.parse(exampleJSON) as DashedOptionTwo
+console.log(exampleParsed)
+```
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DefaultApi.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DefaultApi.md
index 270369707540..9be5ff63ba97 100644
--- a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DefaultApi.md
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/DefaultApi.md
@@ -6,7 +6,9 @@ All URIs are relative to *http://localhost:3000*
 |------------- | ------------- | -------------|
 | [**test**](DefaultApi.md#test) | **GET** /test |  |
 | [**testArray**](DefaultApi.md#testarray) | **GET** /test-array |  |
+| [**testDashedDiscriminator**](DefaultApi.md#testdasheddiscriminator) | **GET** /test-dashed-discriminator |  |
 | [**testDiscriminator**](DefaultApi.md#testdiscriminator) | **GET** /test-discriminator |  |
+| [**testSnakeCaseDiscriminator**](DefaultApi.md#testsnakecasediscriminator) | **GET** /test-snake-case-discriminator |  |
 
 
 
@@ -124,6 +126,63 @@ No authorization required
 [[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
 
 
+## testDashedDiscriminator
+
+> TestDashedDiscriminatorResponse testDashedDiscriminator()
+
+
+
+### Example
+
+```ts
+import {
+  Configuration,
+  DefaultApi,
+} from '';
+import type { TestDashedDiscriminatorRequest } from '';
+
+async function example() {
+  console.log("🚀 Testing  SDK...");
+  const api = new DefaultApi();
+
+  try {
+    const data = await api.testDashedDiscriminator();
+    console.log(data);
+  } catch (error) {
+    console.error(error);
+  }
+}
+
+// Run the test
+example().catch(console.error);
+```
+
+### Parameters
+
+This endpoint does not need any parameter.
+
+### Return type
+
+[**TestDashedDiscriminatorResponse**](TestDashedDiscriminatorResponse.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+- **Content-Type**: Not defined
+- **Accept**: `application/json`
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | OK |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
 ## testDiscriminator
 
 > TestDiscriminatorResponse testDiscriminator()
@@ -180,3 +239,60 @@ No authorization required
 
 [[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
 
+
+## testSnakeCaseDiscriminator
+
+> TestSnakeCaseDiscriminatorResponse testSnakeCaseDiscriminator()
+
+
+
+### Example
+
+```ts
+import {
+  Configuration,
+  DefaultApi,
+} from '';
+import type { TestSnakeCaseDiscriminatorRequest } from '';
+
+async function example() {
+  console.log("🚀 Testing  SDK...");
+  const api = new DefaultApi();
+
+  try {
+    const data = await api.testSnakeCaseDiscriminator();
+    console.log(data);
+  } catch (error) {
+    console.error(error);
+  }
+}
+
+// Run the test
+example().catch(console.error);
+```
+
+### Parameters
+
+This endpoint does not need any parameter.
+
+### Return type
+
+[**TestSnakeCaseDiscriminatorResponse**](TestSnakeCaseDiscriminatorResponse.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+- **Content-Type**: Not defined
+- **Accept**: `application/json`
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | OK |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/SnakeOptionOne.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/SnakeOptionOne.md
new file mode 100644
index 000000000000..c8d5af7be800
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/SnakeOptionOne.md
@@ -0,0 +1,36 @@
+
+# SnakeOptionOne
+
+
+## Properties
+
+Name | Type
+------------ | -------------
+`discriminatorField` | string
+`someProperty` | string
+
+## Example
+
+```typescript
+import type { SnakeOptionOne } from ''
+
+// TODO: Update the object below with actual values
+const example = {
+  "discriminatorField": null,
+  "someProperty": null,
+} satisfies SnakeOptionOne
+
+console.log(example)
+
+// Convert the instance to a JSON string
+const exampleJSON: string = JSON.stringify(example)
+console.log(exampleJSON)
+
+// Parse the JSON string back to an object
+const exampleParsed = JSON.parse(exampleJSON) as SnakeOptionOne
+console.log(exampleParsed)
+```
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/SnakeOptionTwo.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/SnakeOptionTwo.md
new file mode 100644
index 000000000000..0eed7ae3be8d
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/SnakeOptionTwo.md
@@ -0,0 +1,36 @@
+
+# SnakeOptionTwo
+
+
+## Properties
+
+Name | Type
+------------ | -------------
+`discriminatorField` | string
+`someProperty` | string
+
+## Example
+
+```typescript
+import type { SnakeOptionTwo } from ''
+
+// TODO: Update the object below with actual values
+const example = {
+  "discriminatorField": null,
+  "someProperty": null,
+} satisfies SnakeOptionTwo
+
+console.log(example)
+
+// Convert the instance to a JSON string
+const exampleJSON: string = JSON.stringify(example)
+console.log(exampleJSON)
+
+// Parse the JSON string back to an object
+const exampleParsed = JSON.parse(exampleJSON) as SnakeOptionTwo
+console.log(exampleParsed)
+```
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/TestDashedDiscriminatorResponse.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/TestDashedDiscriminatorResponse.md
new file mode 100644
index 000000000000..fb4ff7140908
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/TestDashedDiscriminatorResponse.md
@@ -0,0 +1,36 @@
+
+# TestDashedDiscriminatorResponse
+
+
+## Properties
+
+Name | Type
+------------ | -------------
+`discriminatorField` | string
+`someProperty` | string
+
+## Example
+
+```typescript
+import type { TestDashedDiscriminatorResponse } from ''
+
+// TODO: Update the object below with actual values
+const example = {
+  "discriminatorField": null,
+  "someProperty": null,
+} satisfies TestDashedDiscriminatorResponse
+
+console.log(example)
+
+// Convert the instance to a JSON string
+const exampleJSON: string = JSON.stringify(example)
+console.log(exampleJSON)
+
+// Parse the JSON string back to an object
+const exampleParsed = JSON.parse(exampleJSON) as TestDashedDiscriminatorResponse
+console.log(exampleParsed)
+```
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/docs/TestSnakeCaseDiscriminatorResponse.md b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/TestSnakeCaseDiscriminatorResponse.md
new file mode 100644
index 000000000000..162301502100
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/docs/TestSnakeCaseDiscriminatorResponse.md
@@ -0,0 +1,36 @@
+
+# TestSnakeCaseDiscriminatorResponse
+
+
+## Properties
+
+Name | Type
+------------ | -------------
+`discriminatorField` | string
+`someProperty` | string
+
+## Example
+
+```typescript
+import type { TestSnakeCaseDiscriminatorResponse } from ''
+
+// TODO: Update the object below with actual values
+const example = {
+  "discriminatorField": null,
+  "someProperty": null,
+} satisfies TestSnakeCaseDiscriminatorResponse
+
+console.log(example)
+
+// Convert the instance to a JSON string
+const exampleJSON: string = JSON.stringify(example)
+console.log(exampleJSON)
+
+// Parse the JSON string back to an object
+const exampleParsed = JSON.parse(exampleJSON) as TestSnakeCaseDiscriminatorResponse
+console.log(exampleParsed)
+```
+
+[[Back to top]](#) [[Back to API list]](../README.md#api-endpoints) [[Back to Model list]](../README.md#models) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/DashedOptionOne.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/DashedOptionOne.ts
new file mode 100644
index 000000000000..b68f211af9b0
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/DashedOptionOne.ts
@@ -0,0 +1,86 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * testing oneOf without discriminator
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+import { mapValues } from '../runtime';
+/**
+ * 
+ * @export
+ * @interface DashedOptionOne
+ */
+export interface DashedOptionOne {
+    /**
+     * 
+     * @type {DashedOptionOneDiscriminatorFieldEnum}
+     * @memberof DashedOptionOne
+     */
+    discriminatorField: DashedOptionOneDiscriminatorFieldEnum;
+    /**
+     * 
+     * @type {string}
+     * @memberof DashedOptionOne
+     */
+    someProperty: string;
+}
+
+
+/**
+ * @export
+ */
+export const DashedOptionOneDiscriminatorFieldEnum = {
+    DashedOptionOne: 'dashedOptionOne'
+} as const;
+export type DashedOptionOneDiscriminatorFieldEnum = typeof DashedOptionOneDiscriminatorFieldEnum[keyof typeof DashedOptionOneDiscriminatorFieldEnum];
+
+
+/**
+ * Check if a given object implements the DashedOptionOne interface.
+ */
+export function instanceOfDashedOptionOne(value: object): value is DashedOptionOne {
+    if ((!('discriminatorField' in value) && !('discriminator-field' in value)) || (value['discriminatorField'] === undefined && value['discriminator-field'] === undefined)) return false;
+    if (value['discriminatorField'] !== 'dashedOptionOne' && value['discriminator-field'] !== 'dashedOptionOne') return false;
+    if ((!('someProperty' in value) && !('some-property' in value)) || (value['someProperty'] === undefined && value['some-property'] === undefined)) return false;
+    return true;
+}
+
+export function DashedOptionOneFromJSON(json: any): DashedOptionOne {
+    return DashedOptionOneFromJSONTyped(json, false);
+}
+
+export function DashedOptionOneFromJSONTyped(json: any, ignoreDiscriminator: boolean): DashedOptionOne {
+    if (json == null) {
+        return json;
+    }
+    return {
+        
+        'discriminatorField': json['discriminator-field'],
+        'someProperty': json['some-property'],
+    };
+}
+
+export function DashedOptionOneToJSON(json: any): DashedOptionOne {
+    return DashedOptionOneToJSONTyped(json, false);
+}
+
+export function DashedOptionOneToJSONTyped(value?: DashedOptionOne | null, ignoreDiscriminator: boolean = false): any {
+    if (value == null) {
+        return value;
+    }
+
+    return {
+        
+        'discriminator-field': value['discriminatorField'],
+        'some-property': value['someProperty'],
+    };
+}
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/DashedOptionTwo.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/DashedOptionTwo.ts
new file mode 100644
index 000000000000..82b85c106023
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/DashedOptionTwo.ts
@@ -0,0 +1,86 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * testing oneOf without discriminator
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+import { mapValues } from '../runtime';
+/**
+ * 
+ * @export
+ * @interface DashedOptionTwo
+ */
+export interface DashedOptionTwo {
+    /**
+     * 
+     * @type {DashedOptionTwoDiscriminatorFieldEnum}
+     * @memberof DashedOptionTwo
+     */
+    discriminatorField: DashedOptionTwoDiscriminatorFieldEnum;
+    /**
+     * 
+     * @type {string}
+     * @memberof DashedOptionTwo
+     */
+    someProperty: string;
+}
+
+
+/**
+ * @export
+ */
+export const DashedOptionTwoDiscriminatorFieldEnum = {
+    DashedOptionTwo: 'dashedOptionTwo'
+} as const;
+export type DashedOptionTwoDiscriminatorFieldEnum = typeof DashedOptionTwoDiscriminatorFieldEnum[keyof typeof DashedOptionTwoDiscriminatorFieldEnum];
+
+
+/**
+ * Check if a given object implements the DashedOptionTwo interface.
+ */
+export function instanceOfDashedOptionTwo(value: object): value is DashedOptionTwo {
+    if ((!('discriminatorField' in value) && !('discriminator-field' in value)) || (value['discriminatorField'] === undefined && value['discriminator-field'] === undefined)) return false;
+    if (value['discriminatorField'] !== 'dashedOptionTwo' && value['discriminator-field'] !== 'dashedOptionTwo') return false;
+    if ((!('someProperty' in value) && !('some-property' in value)) || (value['someProperty'] === undefined && value['some-property'] === undefined)) return false;
+    return true;
+}
+
+export function DashedOptionTwoFromJSON(json: any): DashedOptionTwo {
+    return DashedOptionTwoFromJSONTyped(json, false);
+}
+
+export function DashedOptionTwoFromJSONTyped(json: any, ignoreDiscriminator: boolean): DashedOptionTwo {
+    if (json == null) {
+        return json;
+    }
+    return {
+        
+        'discriminatorField': json['discriminator-field'],
+        'someProperty': json['some-property'],
+    };
+}
+
+export function DashedOptionTwoToJSON(json: any): DashedOptionTwo {
+    return DashedOptionTwoToJSONTyped(json, false);
+}
+
+export function DashedOptionTwoToJSONTyped(value?: DashedOptionTwo | null, ignoreDiscriminator: boolean = false): any {
+    if (value == null) {
+        return value;
+    }
+
+    return {
+        
+        'discriminator-field': value['discriminatorField'],
+        'some-property': value['someProperty'],
+    };
+}
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionOne.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionOne.ts
index 11203f329df9..6f706c9d3592 100644
--- a/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionOne.ts
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionOne.ts
@@ -42,6 +42,7 @@ export type OptionOneDiscriminatorFieldEnum = typeof OptionOneDiscriminatorField
  */
 export function instanceOfOptionOne(value: object): value is OptionOne {
     if (!('discriminatorField' in value) || value['discriminatorField'] === undefined) return false;
+    if (value['discriminatorField'] !== 'optionOne') return false;
     return true;
 }
 
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionTwo.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionTwo.ts
index 67fb9241746f..67df352e4660 100644
--- a/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionTwo.ts
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/OptionTwo.ts
@@ -42,6 +42,7 @@ export type OptionTwoDiscriminatorFieldEnum = typeof OptionTwoDiscriminatorField
  */
 export function instanceOfOptionTwo(value: object): value is OptionTwo {
     if (!('discriminatorField' in value) || value['discriminatorField'] === undefined) return false;
+    if (value['discriminatorField'] !== 'optionTwo') return false;
     return true;
 }
 
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/SnakeOptionOne.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/SnakeOptionOne.ts
new file mode 100644
index 000000000000..389d711fc4aa
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/SnakeOptionOne.ts
@@ -0,0 +1,86 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * testing oneOf without discriminator
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+import { mapValues } from '../runtime';
+/**
+ * 
+ * @export
+ * @interface SnakeOptionOne
+ */
+export interface SnakeOptionOne {
+    /**
+     * 
+     * @type {SnakeOptionOneDiscriminatorFieldEnum}
+     * @memberof SnakeOptionOne
+     */
+    discriminatorField: SnakeOptionOneDiscriminatorFieldEnum;
+    /**
+     * 
+     * @type {string}
+     * @memberof SnakeOptionOne
+     */
+    someProperty: string;
+}
+
+
+/**
+ * @export
+ */
+export const SnakeOptionOneDiscriminatorFieldEnum = {
+    SnakeOptionOne: 'snakeOptionOne'
+} as const;
+export type SnakeOptionOneDiscriminatorFieldEnum = typeof SnakeOptionOneDiscriminatorFieldEnum[keyof typeof SnakeOptionOneDiscriminatorFieldEnum];
+
+
+/**
+ * Check if a given object implements the SnakeOptionOne interface.
+ */
+export function instanceOfSnakeOptionOne(value: object): value is SnakeOptionOne {
+    if ((!('discriminatorField' in value) && !('discriminator_field' in value)) || (value['discriminatorField'] === undefined && value['discriminator_field'] === undefined)) return false;
+    if (value['discriminatorField'] !== 'snakeOptionOne' && value['discriminator_field'] !== 'snakeOptionOne') return false;
+    if ((!('someProperty' in value) && !('some_property' in value)) || (value['someProperty'] === undefined && value['some_property'] === undefined)) return false;
+    return true;
+}
+
+export function SnakeOptionOneFromJSON(json: any): SnakeOptionOne {
+    return SnakeOptionOneFromJSONTyped(json, false);
+}
+
+export function SnakeOptionOneFromJSONTyped(json: any, ignoreDiscriminator: boolean): SnakeOptionOne {
+    if (json == null) {
+        return json;
+    }
+    return {
+        
+        'discriminatorField': json['discriminator_field'],
+        'someProperty': json['some_property'],
+    };
+}
+
+export function SnakeOptionOneToJSON(json: any): SnakeOptionOne {
+    return SnakeOptionOneToJSONTyped(json, false);
+}
+
+export function SnakeOptionOneToJSONTyped(value?: SnakeOptionOne | null, ignoreDiscriminator: boolean = false): any {
+    if (value == null) {
+        return value;
+    }
+
+    return {
+        
+        'discriminator_field': value['discriminatorField'],
+        'some_property': value['someProperty'],
+    };
+}
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/SnakeOptionTwo.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/SnakeOptionTwo.ts
new file mode 100644
index 000000000000..10a96d3698d6
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/SnakeOptionTwo.ts
@@ -0,0 +1,86 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * testing oneOf without discriminator
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+import { mapValues } from '../runtime';
+/**
+ * 
+ * @export
+ * @interface SnakeOptionTwo
+ */
+export interface SnakeOptionTwo {
+    /**
+     * 
+     * @type {SnakeOptionTwoDiscriminatorFieldEnum}
+     * @memberof SnakeOptionTwo
+     */
+    discriminatorField: SnakeOptionTwoDiscriminatorFieldEnum;
+    /**
+     * 
+     * @type {string}
+     * @memberof SnakeOptionTwo
+     */
+    someProperty: string;
+}
+
+
+/**
+ * @export
+ */
+export const SnakeOptionTwoDiscriminatorFieldEnum = {
+    SnakeOptionTwo: 'snakeOptionTwo'
+} as const;
+export type SnakeOptionTwoDiscriminatorFieldEnum = typeof SnakeOptionTwoDiscriminatorFieldEnum[keyof typeof SnakeOptionTwoDiscriminatorFieldEnum];
+
+
+/**
+ * Check if a given object implements the SnakeOptionTwo interface.
+ */
+export function instanceOfSnakeOptionTwo(value: object): value is SnakeOptionTwo {
+    if ((!('discriminatorField' in value) && !('discriminator_field' in value)) || (value['discriminatorField'] === undefined && value['discriminator_field'] === undefined)) return false;
+    if (value['discriminatorField'] !== 'snakeOptionTwo' && value['discriminator_field'] !== 'snakeOptionTwo') return false;
+    if ((!('someProperty' in value) && !('some_property' in value)) || (value['someProperty'] === undefined && value['some_property'] === undefined)) return false;
+    return true;
+}
+
+export function SnakeOptionTwoFromJSON(json: any): SnakeOptionTwo {
+    return SnakeOptionTwoFromJSONTyped(json, false);
+}
+
+export function SnakeOptionTwoFromJSONTyped(json: any, ignoreDiscriminator: boolean): SnakeOptionTwo {
+    if (json == null) {
+        return json;
+    }
+    return {
+        
+        'discriminatorField': json['discriminator_field'],
+        'someProperty': json['some_property'],
+    };
+}
+
+export function SnakeOptionTwoToJSON(json: any): SnakeOptionTwo {
+    return SnakeOptionTwoToJSONTyped(json, false);
+}
+
+export function SnakeOptionTwoToJSONTyped(value?: SnakeOptionTwo | null, ignoreDiscriminator: boolean = false): any {
+    if (value == null) {
+        return value;
+    }
+
+    return {
+        
+        'discriminator_field': value['discriminatorField'],
+        'some_property': value['someProperty'],
+    };
+}
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestDashedDiscriminatorResponse.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestDashedDiscriminatorResponse.ts
new file mode 100644
index 000000000000..dc5d587d0429
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestDashedDiscriminatorResponse.ts
@@ -0,0 +1,72 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * testing oneOf without discriminator
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+import type { DashedOptionOne } from './DashedOptionOne';
+import {
+    instanceOfDashedOptionOne,
+    DashedOptionOneFromJSON,
+    DashedOptionOneFromJSONTyped,
+    DashedOptionOneToJSON,
+} from './DashedOptionOne';
+import type { DashedOptionTwo } from './DashedOptionTwo';
+import {
+    instanceOfDashedOptionTwo,
+    DashedOptionTwoFromJSON,
+    DashedOptionTwoFromJSONTyped,
+    DashedOptionTwoToJSON,
+} from './DashedOptionTwo';
+
+/**
+ * @type TestDashedDiscriminatorResponse
+ * 
+ * @export
+ */
+export type TestDashedDiscriminatorResponse = { discriminatorField: 'dashedOptionOne' } & DashedOptionOne | { discriminatorField: 'dashedOptionTwo' } & DashedOptionTwo;
+
+export function TestDashedDiscriminatorResponseFromJSON(json: any): TestDashedDiscriminatorResponse {
+    return TestDashedDiscriminatorResponseFromJSONTyped(json, false);
+}
+
+export function TestDashedDiscriminatorResponseFromJSONTyped(json: any, ignoreDiscriminator: boolean): TestDashedDiscriminatorResponse {
+    if (json == null) {
+        return json;
+    }
+    switch (json['discriminator-field']) {
+        case 'dashedOptionOne':
+            return Object.assign({}, DashedOptionOneFromJSONTyped(json, true), { discriminatorField: 'dashedOptionOne' } as const);
+        case 'dashedOptionTwo':
+            return Object.assign({}, DashedOptionTwoFromJSONTyped(json, true), { discriminatorField: 'dashedOptionTwo' } as const);
+        default:
+            return json;
+    }
+}
+
+export function TestDashedDiscriminatorResponseToJSON(json: any): any {
+    return TestDashedDiscriminatorResponseToJSONTyped(json, false);
+}
+
+export function TestDashedDiscriminatorResponseToJSONTyped(value?: TestDashedDiscriminatorResponse | null, ignoreDiscriminator: boolean = false): any {
+    if (value == null) {
+        return value;
+    }
+    switch (value['discriminatorField']) {
+        case 'dashedOptionOne':
+            return Object.assign({}, DashedOptionOneToJSON(value), { discriminatorField: 'dashedOptionOne' } as const);
+        case 'dashedOptionTwo':
+            return Object.assign({}, DashedOptionTwoToJSON(value), { discriminatorField: 'dashedOptionTwo' } as const);
+        default:
+            return value;
+    }
+}
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestSnakeCaseDiscriminatorResponse.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestSnakeCaseDiscriminatorResponse.ts
new file mode 100644
index 000000000000..88da169b3516
--- /dev/null
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestSnakeCaseDiscriminatorResponse.ts
@@ -0,0 +1,72 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * testing oneOf without discriminator
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+import type { SnakeOptionOne } from './SnakeOptionOne';
+import {
+    instanceOfSnakeOptionOne,
+    SnakeOptionOneFromJSON,
+    SnakeOptionOneFromJSONTyped,
+    SnakeOptionOneToJSON,
+} from './SnakeOptionOne';
+import type { SnakeOptionTwo } from './SnakeOptionTwo';
+import {
+    instanceOfSnakeOptionTwo,
+    SnakeOptionTwoFromJSON,
+    SnakeOptionTwoFromJSONTyped,
+    SnakeOptionTwoToJSON,
+} from './SnakeOptionTwo';
+
+/**
+ * @type TestSnakeCaseDiscriminatorResponse
+ * 
+ * @export
+ */
+export type TestSnakeCaseDiscriminatorResponse = { discriminatorField: 'snakeOptionOne' } & SnakeOptionOne | { discriminatorField: 'snakeOptionTwo' } & SnakeOptionTwo;
+
+export function TestSnakeCaseDiscriminatorResponseFromJSON(json: any): TestSnakeCaseDiscriminatorResponse {
+    return TestSnakeCaseDiscriminatorResponseFromJSONTyped(json, false);
+}
+
+export function TestSnakeCaseDiscriminatorResponseFromJSONTyped(json: any, ignoreDiscriminator: boolean): TestSnakeCaseDiscriminatorResponse {
+    if (json == null) {
+        return json;
+    }
+    switch (json['discriminator_field']) {
+        case 'snakeOptionOne':
+            return Object.assign({}, SnakeOptionOneFromJSONTyped(json, true), { discriminatorField: 'snakeOptionOne' } as const);
+        case 'snakeOptionTwo':
+            return Object.assign({}, SnakeOptionTwoFromJSONTyped(json, true), { discriminatorField: 'snakeOptionTwo' } as const);
+        default:
+            return json;
+    }
+}
+
+export function TestSnakeCaseDiscriminatorResponseToJSON(json: any): any {
+    return TestSnakeCaseDiscriminatorResponseToJSONTyped(json, false);
+}
+
+export function TestSnakeCaseDiscriminatorResponseToJSONTyped(value?: TestSnakeCaseDiscriminatorResponse | null, ignoreDiscriminator: boolean = false): any {
+    if (value == null) {
+        return value;
+    }
+    switch (value['discriminatorField']) {
+        case 'snakeOptionOne':
+            return Object.assign({}, SnakeOptionOneToJSON(value), { discriminatorField: 'snakeOptionOne' } as const);
+        case 'snakeOptionTwo':
+            return Object.assign({}, SnakeOptionTwoToJSON(value), { discriminatorField: 'snakeOptionTwo' } as const);
+        default:
+            return value;
+    }
+}
+
diff --git a/samples/client/petstore/typescript-fetch/builds/oneOf/models/index.ts b/samples/client/petstore/typescript-fetch/builds/oneOf/models/index.ts
index 79f8303e9ed5..dd6f84c6f02d 100644
--- a/samples/client/petstore/typescript-fetch/builds/oneOf/models/index.ts
+++ b/samples/client/petstore/typescript-fetch/builds/oneOf/models/index.ts
@@ -1,9 +1,15 @@
 /* tslint:disable */
 /* eslint-disable */
+export * from './DashedOptionOne';
+export * from './DashedOptionTwo';
 export * from './OptionOne';
 export * from './OptionTwo';
+export * from './SnakeOptionOne';
+export * from './SnakeOptionTwo';
 export * from './TestA';
 export * from './TestArrayResponse';
 export * from './TestB';
+export * from './TestDashedDiscriminatorResponse';
 export * from './TestDiscriminatorResponse';
 export * from './TestResponse';
+export * from './TestSnakeCaseDiscriminatorResponse';
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/Animal.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/Animal.ts
index 6d1cb238fc7a..790ff584911a 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/Animal.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/Animal.ts
@@ -39,7 +39,7 @@ export interface Animal {
  * Check if a given object implements the Animal interface.
  */
 export function instanceOfAnimal(value: object): value is Animal {
-    if (!('className' in value) || value['className'] === undefined) return false;
+    if ((!('className' in value) && !('class_name' in value)) || (value['className'] === undefined && value['class_name'] === undefined)) return false;
     return true;
 }
 
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/EnumTest.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/EnumTest.ts
index a5eecc180343..6890904e62b9 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/EnumTest.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/EnumTest.ts
@@ -142,7 +142,7 @@ export type EnumTestEnumNumberEnum = typeof EnumTestEnumNumberEnum[keyof typeof
  * Check if a given object implements the EnumTest interface.
  */
 export function instanceOfEnumTest(value: object): value is EnumTest {
-    if (!('enumStringRequired' in value) || value['enumStringRequired'] === undefined) return false;
+    if ((!('enumStringRequired' in value) && !('enum_string_required' in value)) || (value['enumStringRequired'] === undefined && value['enum_string_required'] === undefined)) return false;
     return true;
 }
 
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/FormatTest.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/FormatTest.ts
index f695e974f39d..822bb60636fb 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/FormatTest.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/models/FormatTest.ts
@@ -122,7 +122,7 @@ export interface FormatTest {
  */
 export function instanceOfFormatTest(value: object): value is FormatTest {
     if (!('number' in value) || value['number'] === undefined) return false;
-    if (!('_byte' in value) || value['_byte'] === undefined) return false;
+    if ((!('_byte' in value) && !('byte' in value)) || (value['_byte'] === undefined && value['byte'] === undefined)) return false;
     if (!('date' in value) || value['date'] === undefined) return false;
     if (!('password' in value) || value['password'] === undefined) return false;
     return true;