Core: Adding additional information in RestException

core/src/main/java/org/apache/iceberg/rest/ErrorHandlers.java

@@ -235,8 +235,6 @@ public void accept(ErrorResponse error) {
           throw new NoSuchNamespaceException("%s", error.message());
         case 409:
           throw new AlreadyExistsException("%s", error.message());
-        case 422:
-          throw new RESTException("Unable to process: %s", error.message());
       }
 
       super.accept(error);
@@ -297,7 +295,9 @@ public void accept(ErrorResponse error) {
           throw new ServiceUnavailableException("Service unavailable: %s", error.message());
       }
 
-      throw new RESTException("Unable to process: %s", error.message());
+      throw new RESTException(
+          "Unable to process (code: %s, type: %s): %s",
+          error.code(), error.type(), error.message());
     }
   }
 
@@ -330,7 +330,9 @@ public void accept(ErrorResponse error) {
                 "Malformed request: %s: %s", error.type(), error.message());
         }
       }
-      throw new RESTException("Unable to process: %s", error.message());
+      throw new RESTException(
+          "Unable to process (code: %s, type: %s): %s",
+          error.code(), error.type(), error.message());
     }
   }
 }

core/src/test/java/org/apache/iceberg/rest/TestErrorHandlers.java

@@ -0,0 +1,101 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.iceberg.rest;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.apache.iceberg.exceptions.RESTException;
+import org.apache.iceberg.rest.responses.ErrorResponse;
+import org.junit.jupiter.api.Test;
+
+class TestErrorHandlers {
+
+  @Test
+  public void testErrorHandlerIncludesCodeAndType() {
+    ErrorResponse error =
+        ErrorResponse.builder()
+            .responseCode(422)
+            .withType("ValidationException")
+            .withMessage("Invalid input")
+            .build();
+
+    assertThatThrownBy(() -> ErrorHandlers.defaultErrorHandler().accept(error))
+        .isInstanceOf(RESTException.class)
+        .hasMessageContaining(
+            "Unable to process (code: 422, type: ValidationException): Invalid input");
+  }
+
+  @Test
+  public void testErrorHandlerWithCodeOnly() {
+    ErrorResponse error = ErrorResponse.builder().responseCode(422).build();
+
+    assertThatThrownBy(() -> ErrorHandlers.defaultErrorHandler().accept(error))
+        .isInstanceOf(RESTException.class)
+        .hasMessageContaining("Unable to process (code: 422, type: null): null");
+  }
+
+  @Test
+  public void testErrorHandlerWithCodeAndMessageOnly() {
+    ErrorResponse error =
+        ErrorResponse.builder().responseCode(422).withMessage("Invalid input").build();
+
+    assertThatThrownBy(() -> ErrorHandlers.defaultErrorHandler().accept(error))
+        .isInstanceOf(RESTException.class)
+        .hasMessageContaining("Unable to process (code: 422, type: null): Invalid input");
+  }
+
+  @Test
+  public void testErrorHandlerWithCodeAndTypeOnly() {
+    ErrorResponse error =
+        ErrorResponse.builder().responseCode(422).withType("ValidationException").build();
+
+    assertThatThrownBy(() -> ErrorHandlers.defaultErrorHandler().accept(error))
+        .isInstanceOf(RESTException.class)
+        .hasMessageContaining("Unable to process (code: 422, type: ValidationException): null");
+  }
+
+  @Test
+  public void testNamespaceErrorHandlerFallsBackToDefaultFor422() {
+    ErrorResponse error =
+        ErrorResponse.builder()
+            .responseCode(422)
+            .withType("ValidationException")
+            .withMessage("Invalid input")
+            .build();
+
+    // NamespaceErrorHandler should fall back to DefaultErrorHandler for 422,
+    // which includes code, type, and message in the error message
+    assertThatThrownBy(() -> ErrorHandlers.namespaceErrorHandler().accept(error))
+        .isInstanceOf(RESTException.class)
+        .hasMessageContaining(
+            "Unable to process (code: 422, type: ValidationException): Invalid input");
+  }
+
+  @Test
+  public void testNamespaceErrorHandlerFallsBackToDefaultFor422WithOptionalFields() {
+    ErrorResponse error =
+        ErrorResponse.builder().responseCode(422).withMessage("Invalid input").build();
+
+    // NamespaceErrorHandler should fall back to DefaultErrorHandler for 422,
+    // even when type is missing
+    assertThatThrownBy(() -> ErrorHandlers.namespaceErrorHandler().accept(error))
+        .isInstanceOf(RESTException.class)
+        .hasMessageContaining("Unable to process (code: 422, type: null): Invalid input");
+  }
+}