Improve error handling

Author: MarkRobbo

src/main/java/org/commonwl/view/GlobalControllerErrorHandling.java

@@ -0,0 +1,61 @@
+/*
+ * 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.commonwl.view;
+
+import org.commonwl.view.workflow.RepresentationNotFoundException;
+import org.commonwl.view.workflow.WorkflowNotFoundException;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+
+/**
+ * Handles exception handling across the application
+ */
+@ControllerAdvice
+public class GlobalControllerErrorHandling {
+
+    /**
+     * Workflow can not be found
+     * @return A plain text error message
+     */
+    @ExceptionHandler(WorkflowNotFoundException.class)
+    public ResponseEntity<?> handleNotFound() {
+        final HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.TEXT_PLAIN);
+        return new ResponseEntity<>("Workflow could not be found", headers, HttpStatus.NOT_FOUND);
+    }
+
+    /**
+     * Workflow exists but representation is not found
+     * eg Generic git workflow asking for raw workflow URL
+     * @return A plain text error message
+     */
+    @ExceptionHandler(RepresentationNotFoundException.class)
+    public ResponseEntity<?> handleNoRepresentation() {
+        final HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.TEXT_PLAIN);
+        return new ResponseEntity<>("The workflow exists but the requested representation could not be found",
+                headers, HttpStatus.NOT_FOUND);
+    }
+
+}

src/main/java/org/commonwl/view/workflow/RepresentationNotFoundException.java

@@ -0,0 +1,30 @@
+/*
+ * 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.commonwl.view.workflow;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+/**
+ * Exception thrown when a workflow representation was not found
+ */
+@ResponseStatus(value = HttpStatus.NOT_ACCEPTABLE)
+public class RepresentationNotFoundException extends RuntimeException {
+}

src/main/java/org/commonwl/view/workflow/WorkflowPermalinkController.java

@@ -74,7 +74,7 @@ public void goToViewer(@PathVariable("commitid") String commitId,
     /**
      * Redirect to the raw file if this exists
      * @param commitId The commit ID of the workflow
-     * @return A 302 redirect response to the raw URL or 404
+     * @return A 302 redirect response to the raw URL or 406
      */
     @GetMapping(value = "/git/{commitid}/**",
                 produces = {"application/x-yaml", MediaType.APPLICATION_OCTET_STREAM_VALUE, "*/*"})
@@ -83,7 +83,7 @@ public void goToRawUrl(@PathVariable("commitid") String commitId,
                            HttpServletResponse response) {
         Workflow workflow = getWorkflow(commitId, request);
         if (workflow.getRetrievedFrom().getType() == GitType.GENERIC) {
-            response.setStatus(HttpServletResponse.SC_NOT_FOUND);
+            throw new RepresentationNotFoundException();
         } else {
             response.setHeader("Location", workflow.getRetrievedFrom().getRawUrl(commitId));
             response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);