[http-client-java] fix discriminator with no subtypes

.chronus/changes/java_fix_discriminator_no_subtypes-2026-2-18-19-29-57.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-java"
+---
+
+Fix discriminator property not generated when model has @discriminator but no known subtypes

packages/http-client-java/emitter/src/code-model-builder.ts

@@ -2829,13 +2829,15 @@ export class CodeModelBuilder {
     }
 
     // discriminator
-    if (type.discriminatedSubtypes && type.discriminatorProperty) {
+    if (type.discriminatorProperty) {
       objectSchema.discriminator = new Discriminator(
         this.processModelProperty(type.discriminatorProperty),
       );
-      for (const discriminatorValue in type.discriminatedSubtypes) {
-        const subType = type.discriminatedSubtypes[discriminatorValue];
-        this.processSchema(subType, subType.name);
+      if (type.discriminatedSubtypes) {
+        for (const discriminatorValue in type.discriminatedSubtypes) {
+          const subType = type.discriminatedSubtypes[discriminatorValue];
+          this.processSchema(subType, subType.name);
+        }
       }
     }
 

packages/http-client-java/generator/http-client-generator-test/src/main/java/tsptest/discriminatoredgecases/DiscriminatorEdgeCasesAsyncClient.java

@@ -20,6 +20,7 @@
 import tsptest.discriminatoredgecases.implementation.DiscriminatorEdgeCasesClientImpl;
 import tsptest.discriminatoredgecases.models.ChildWithAnotherDiscriminator;
 import tsptest.discriminatoredgecases.models.ChildWithRequiredPropertyAsDiscriminator;
+import tsptest.discriminatoredgecases.models.ModelWithDiscriminatorNoSubtypes;
 
 /**
  * Initializes a new instance of the asynchronous DiscriminatorEdgeCasesClient type.
@@ -94,6 +95,32 @@ public Mono<Response<BinaryData>> getChildNewDiscrimWithResponse(RequestOptions
         return this.serviceClient.getChildNewDiscrimWithResponseAsync(requestOptions);
     }
 
+    /**
+     * The getNoSubtypes operation.
+     * <p><strong>Response Body Schema</strong></p>
+     * 
+     * <pre>
+     * {@code
+     * {
+     *     kind: String (Required)
+     *     name: String (Required)
+     * }
+     * }
+     * </pre>
+     * 
+     * @param requestOptions The options to configure the HTTP request before HTTP client sends it.
+     * @throws HttpResponseException thrown if the request is rejected by server.
+     * @throws ClientAuthenticationException thrown if the request is rejected by server on status code 401.
+     * @throws ResourceNotFoundException thrown if the request is rejected by server on status code 404.
+     * @throws ResourceModifiedException thrown if the request is rejected by server on status code 409.
+     * @return model with along with {@link Response} on successful completion of {@link Mono}.
+     */
+    @Generated
+    @ServiceMethod(returns = ReturnType.SINGLE)
+    public Mono<Response<BinaryData>> getNoSubtypesWithResponse(RequestOptions requestOptions) {
+        return this.serviceClient.getNoSubtypesWithResponseAsync(requestOptions);
+    }
+
     /**
      * The getChildRequiredDiscrim operation.
      * 
@@ -131,4 +158,23 @@ public Mono<ChildWithAnotherDiscriminator> getChildNewDiscrim() {
         return getChildNewDiscrimWithResponse(requestOptions).flatMap(FluxUtil::toMono)
             .map(protocolMethodData -> protocolMethodData.toObject(ChildWithAnotherDiscriminator.class));
     }
+
+    /**
+     * The getNoSubtypes operation.
+     * 
+     * @throws HttpResponseException thrown if the request is rejected by server.
+     * @throws ClientAuthenticationException thrown if the request is rejected by server on status code 401.
+     * @throws ResourceNotFoundException thrown if the request is rejected by server on status code 404.
+     * @throws ResourceModifiedException thrown if the request is rejected by server on status code 409.
+     * @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent.
+     * @return model with on successful completion of {@link Mono}.
+     */
+    @Generated
+    @ServiceMethod(returns = ReturnType.SINGLE)
+    public Mono<ModelWithDiscriminatorNoSubtypes> getNoSubtypes() {
+        // Generated convenience method for getNoSubtypesWithResponse
+        RequestOptions requestOptions = new RequestOptions();
+        return getNoSubtypesWithResponse(requestOptions).flatMap(FluxUtil::toMono)
+            .map(protocolMethodData -> protocolMethodData.toObject(ModelWithDiscriminatorNoSubtypes.class));
+    }
 }

packages/http-client-java/generator/http-client-generator-test/src/main/java/tsptest/discriminatoredgecases/DiscriminatorEdgeCasesClient.java

@@ -18,6 +18,7 @@
 import tsptest.discriminatoredgecases.implementation.DiscriminatorEdgeCasesClientImpl;
 import tsptest.discriminatoredgecases.models.ChildWithAnotherDiscriminator;
 import tsptest.discriminatoredgecases.models.ChildWithRequiredPropertyAsDiscriminator;
+import tsptest.discriminatoredgecases.models.ModelWithDiscriminatorNoSubtypes;
 
 /**
  * Initializes a new instance of the synchronous DiscriminatorEdgeCasesClient type.
@@ -92,6 +93,32 @@ public Response<BinaryData> getChildNewDiscrimWithResponse(RequestOptions reques
         return this.serviceClient.getChildNewDiscrimWithResponse(requestOptions);
     }
 
+    /**
+     * The getNoSubtypes operation.
+     * <p><strong>Response Body Schema</strong></p>
+     * 
+     * <pre>
+     * {@code
+     * {
+     *     kind: String (Required)
+     *     name: String (Required)
+     * }
+     * }
+     * </pre>
+     * 
+     * @param requestOptions The options to configure the HTTP request before HTTP client sends it.
+     * @throws HttpResponseException thrown if the request is rejected by server.
+     * @throws ClientAuthenticationException thrown if the request is rejected by server on status code 401.
+     * @throws ResourceNotFoundException thrown if the request is rejected by server on status code 404.
+     * @throws ResourceModifiedException thrown if the request is rejected by server on status code 409.
+     * @return model with along with {@link Response}.
+     */
+    @Generated
+    @ServiceMethod(returns = ReturnType.SINGLE)
+    public Response<BinaryData> getNoSubtypesWithResponse(RequestOptions requestOptions) {
+        return this.serviceClient.getNoSubtypesWithResponse(requestOptions);
+    }
+
     /**
      * The getChildRequiredDiscrim operation.
      * 
@@ -128,4 +155,22 @@ public ChildWithAnotherDiscriminator getChildNewDiscrim() {
         RequestOptions requestOptions = new RequestOptions();
         return getChildNewDiscrimWithResponse(requestOptions).getValue().toObject(ChildWithAnotherDiscriminator.class);
     }
+
+    /**
+     * The getNoSubtypes operation.
+     * 
+     * @throws HttpResponseException thrown if the request is rejected by server.
+     * @throws ClientAuthenticationException thrown if the request is rejected by server on status code 401.
+     * @throws ResourceNotFoundException thrown if the request is rejected by server on status code 404.
+     * @throws ResourceModifiedException thrown if the request is rejected by server on status code 409.
+     * @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent.
+     * @return model with.
+     */
+    @Generated
+    @ServiceMethod(returns = ReturnType.SINGLE)
+    public ModelWithDiscriminatorNoSubtypes getNoSubtypes() {
+        // Generated convenience method for getNoSubtypesWithResponse
+        RequestOptions requestOptions = new RequestOptions();
+        return getNoSubtypesWithResponse(requestOptions).getValue().toObject(ModelWithDiscriminatorNoSubtypes.class);
+    }
 }

packages/http-client-java/generator/http-client-generator-test/src/main/java/tsptest/discriminatoredgecases/implementation/DiscriminatorEdgeCasesClientImpl.java

@@ -160,6 +160,24 @@ Mono<Response<BinaryData>> getChildNewDiscrim(@HostParam("endpoint") String endp
         @UnexpectedResponseExceptionType(HttpResponseException.class)
         Response<BinaryData> getChildNewDiscrimSync(@HostParam("endpoint") String endpoint,
             @HeaderParam("Accept") String accept, RequestOptions requestOptions, Context context);
+
+        @Get("/model/nosubtypes")
+        @ExpectedResponses({ 200 })
+        @UnexpectedResponseExceptionType(value = ClientAuthenticationException.class, code = { 401 })
+        @UnexpectedResponseExceptionType(value = ResourceNotFoundException.class, code = { 404 })
+        @UnexpectedResponseExceptionType(value = ResourceModifiedException.class, code = { 409 })
+        @UnexpectedResponseExceptionType(HttpResponseException.class)
+        Mono<Response<BinaryData>> getNoSubtypes(@HostParam("endpoint") String endpoint,
+            @HeaderParam("Accept") String accept, RequestOptions requestOptions, Context context);
+
+        @Get("/model/nosubtypes")
+        @ExpectedResponses({ 200 })
+        @UnexpectedResponseExceptionType(value = ClientAuthenticationException.class, code = { 401 })
+        @UnexpectedResponseExceptionType(value = ResourceNotFoundException.class, code = { 404 })
+        @UnexpectedResponseExceptionType(value = ResourceModifiedException.class, code = { 409 })
+        @UnexpectedResponseExceptionType(HttpResponseException.class)
+        Response<BinaryData> getNoSubtypesSync(@HostParam("endpoint") String endpoint,
+            @HeaderParam("Accept") String accept, RequestOptions requestOptions, Context context);
     }
 
     /**
@@ -273,4 +291,57 @@ public Response<BinaryData> getChildNewDiscrimWithResponse(RequestOptions reques
         final String accept = "application/json";
         return service.getChildNewDiscrimSync(this.getEndpoint(), accept, requestOptions, Context.NONE);
     }
+
+    /**
+     * The getNoSubtypes operation.
+     * <p><strong>Response Body Schema</strong></p>
+     * 
+     * <pre>
+     * {@code
+     * {
+     *     kind: String (Required)
+     *     name: String (Required)
+     * }
+     * }
+     * </pre>
+     * 
+     * @param requestOptions The options to configure the HTTP request before HTTP client sends it.
+     * @throws HttpResponseException thrown if the request is rejected by server.
+     * @throws ClientAuthenticationException thrown if the request is rejected by server on status code 401.
+     * @throws ResourceNotFoundException thrown if the request is rejected by server on status code 404.
+     * @throws ResourceModifiedException thrown if the request is rejected by server on status code 409.
+     * @return model with along with {@link Response} on successful completion of {@link Mono}.
+     */
+    @ServiceMethod(returns = ReturnType.SINGLE)
+    public Mono<Response<BinaryData>> getNoSubtypesWithResponseAsync(RequestOptions requestOptions) {
+        final String accept = "application/json";
+        return FluxUtil
+            .withContext(context -> service.getNoSubtypes(this.getEndpoint(), accept, requestOptions, context));
+    }
+
+    /**
+     * The getNoSubtypes operation.
+     * <p><strong>Response Body Schema</strong></p>
+     * 
+     * <pre>
+     * {@code
+     * {
+     *     kind: String (Required)
+     *     name: String (Required)
+     * }
+     * }
+     * </pre>
+     * 
+     * @param requestOptions The options to configure the HTTP request before HTTP client sends it.
+     * @throws HttpResponseException thrown if the request is rejected by server.
+     * @throws ClientAuthenticationException thrown if the request is rejected by server on status code 401.
+     * @throws ResourceNotFoundException thrown if the request is rejected by server on status code 404.
+     * @throws ResourceModifiedException thrown if the request is rejected by server on status code 409.
+     * @return model with along with {@link Response}.
+     */
+    @ServiceMethod(returns = ReturnType.SINGLE)
+    public Response<BinaryData> getNoSubtypesWithResponse(RequestOptions requestOptions) {
+        final String accept = "application/json";
+        return service.getNoSubtypesSync(this.getEndpoint(), accept, requestOptions, Context.NONE);
+    }
 }

packages/http-client-java/generator/http-client-generator-test/src/main/java/tsptest/discriminatoredgecases/models/ModelWithDiscriminatorNoSubtypes.java

@@ -0,0 +1,107 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+// Code generated by Microsoft (R) TypeSpec Code Generator.
+
+package tsptest.discriminatoredgecases.models;
+
+import com.azure.core.annotation.Generated;
+import com.azure.core.annotation.Immutable;
+import com.azure.json.JsonReader;
+import com.azure.json.JsonSerializable;
+import com.azure.json.JsonToken;
+import com.azure.json.JsonWriter;
+import java.io.IOException;
+
+/**
+ * Model with.
+ */
+@Immutable
+public final class ModelWithDiscriminatorNoSubtypes implements JsonSerializable<ModelWithDiscriminatorNoSubtypes> {
+    /*
+     * The kind property.
+     */
+    @Generated
+    private String kind = "ModelWithDiscriminatorNoSubtypes";
+
+    /*
+     * The name property.
+     */
+    @Generated
+    private final String name;
+
+    /**
+     * Creates an instance of ModelWithDiscriminatorNoSubtypes class.
+     * 
+     * @param name the name value to set.
+     */
+    @Generated
+    private ModelWithDiscriminatorNoSubtypes(String name) {
+        this.name = name;
+    }
+
+    /**
+     * Get the kind property: The kind property.
+     * 
+     * @return the kind value.
+     */
+    @Generated
+    public String getKind() {
+        return this.kind;
+    }
+
+    /**
+     * Get the name property: The name property.
+     * 
+     * @return the name value.
+     */
+    @Generated
+    public String getName() {
+        return this.name;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Generated
+    @Override
+    public JsonWriter toJson(JsonWriter jsonWriter) throws IOException {
+        jsonWriter.writeStartObject();
+        jsonWriter.writeStringField("name", this.name);
+        jsonWriter.writeStringField("kind", this.kind);
+        return jsonWriter.writeEndObject();
+    }
+
+    /**
+     * Reads an instance of ModelWithDiscriminatorNoSubtypes from the JsonReader.
+     * 
+     * @param jsonReader The JsonReader being read.
+     * @return An instance of ModelWithDiscriminatorNoSubtypes if the JsonReader was pointing to an instance of it, or
+     * null if it was pointing to JSON null.
+     * @throws IllegalStateException If the deserialized JSON object was missing any required properties.
+     * @throws IOException If an error occurs while reading the ModelWithDiscriminatorNoSubtypes.
+     */
+    @Generated
+    public static ModelWithDiscriminatorNoSubtypes fromJson(JsonReader jsonReader) throws IOException {
+        return jsonReader.readObject(reader -> {
+            String name = null;
+            String kind = null;
+            while (reader.nextToken() != JsonToken.END_OBJECT) {
+                String fieldName = reader.getFieldName();
+                reader.nextToken();
+
+                if ("name".equals(fieldName)) {
+                    name = reader.getString();
+                } else if ("kind".equals(fieldName)) {
+                    kind = reader.getString();
+                } else {
+                    reader.skipChildren();
+                }
+            }
+            ModelWithDiscriminatorNoSubtypes deserializedModelWithDiscriminatorNoSubtypes
+                = new ModelWithDiscriminatorNoSubtypes(name);
+            deserializedModelWithDiscriminatorNoSubtypes.kind = kind;
+
+            return deserializedModelWithDiscriminatorNoSubtypes;
+        });
+    }
+}