DGS-1546 Map JsonMappingException to 400 response (#243)

core/src/main/java/io/confluent/rest/Application.java

@@ -77,6 +77,7 @@
 import io.confluent.rest.exceptions.ConstraintViolationExceptionMapper;
 import io.confluent.rest.exceptions.GenericExceptionMapper;
 import io.confluent.rest.exceptions.WebApplicationExceptionMapper;
+import io.confluent.rest.exceptions.JsonMappingExceptionMapper;
 import io.confluent.rest.extension.ResourceExtension;
 import io.confluent.rest.filters.CsrfTokenProtectionFilter;
 import io.confluent.rest.metrics.MetricsResourceMethodApplicationListener;
@@ -568,6 +569,7 @@ protected void registerFeatures(Configurable<?> config, T restConfig) {
    */
   protected void registerExceptionMappers(Configurable<?> config, T restConfig) {
     config.register(ConstraintViolationExceptionMapper.class);
+    config.register(JsonMappingExceptionMapper.class);
     config.register(new WebApplicationExceptionMapper(restConfig));
     config.register(new GenericExceptionMapper(restConfig));
   }

core/src/main/java/io/confluent/rest/exceptions/JsonMappingExceptionMapper.java

@@ -0,0 +1,42 @@
+/**
+ * Copyright 2021 Confluent Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.confluent.rest.exceptions;
+
+import com.fasterxml.jackson.databind.JsonMappingException;
+import io.confluent.rest.entities.ErrorMessage;
+
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+import javax.ws.rs.ext.Provider;
+
+@Provider
+public class JsonMappingExceptionMapper implements ExceptionMapper<JsonMappingException> {
+
+  public static final int BAD_REQUEST_CODE = 400;
+
+  @Override
+  public Response toResponse(JsonMappingException exception) {
+    ErrorMessage message = new ErrorMessage(
+        BAD_REQUEST_CODE,
+        exception.getMessage()
+    );
+
+    return Response.status(BAD_REQUEST_CODE)
+        .entity(message)
+        .build();
+  }
+}

core/src/test/java/io/confluent/rest/JsonMappingExceptionMapperTest.java

@@ -0,0 +1,64 @@
+/**
+ * Copyright 2021 Confluent Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.confluent.rest;
+
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.confluent.rest.entities.ErrorMessage;
+import io.confluent.rest.exceptions.JsonMappingExceptionMapper;
+import org.junit.Before;
+import org.junit.Test;
+
+import javax.ws.rs.core.Response;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class JsonMappingExceptionMapperTest {
+
+  private JsonMappingExceptionMapper mapper;
+
+  @Before
+  public void setUp() {
+    mapper = new JsonMappingExceptionMapper();
+  }
+
+  @Test
+  public void testJsonMappingException() {
+    try {
+      String json = "{\"name\":{}}";
+      ObjectMapper mapper = new ObjectMapper();
+      // try to parse a json where the User name is expecting a string but input an Object
+      mapper.reader().forType(User.class).readValue(json);
+    } catch (JsonMappingException e) {
+      Response response = mapper.toResponse(e);
+      assertEquals(400, response.getStatus());
+      ErrorMessage out = (ErrorMessage)response.getEntity();
+      assertEquals(400, out.getErrorCode());
+    } catch (Exception e) {
+      fail("A JsonMappingException is expected.");
+    }
+  }
+
+  class User {
+    public String name;
+
+    User(String name) {
+      this.name = name;
+    }
+  }
+}