[ISSUE-114] Better expose underlying errors

CHANGELOG.md

@@ -5,6 +5,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## 2.1.1 (UNRELEASED)
 #### New Features
 - Added ability to Copy previously created views.
+- Better expose underlying exceptions/errors when things go wrong.
 
 #### Bug fixes
 - [ISSUE-116](https://github.com/SourceLabOrg/kafka-webview/issues/116) No longer require KeyStore and KeyStore password when configuring a SSL+SASL cluster.

kafka-webview-ui/src/main/java/org/sourcelab/kafka/webview/ui/controller/api/ApiController.java

@@ -570,7 +570,7 @@ public boolean removeConsumer(
     @ExceptionHandler(ApiException.class)
     @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
     public ApiErrorResponse handleApiException(final ApiException exception) {
-        return new ApiErrorResponse(exception.getType(), exception.getMessage());
+        return new ApiErrorResponse(exception.getType(), exception.getMessage(), ApiErrorResponse.buildCauseList(exception));
     }
 
     /**

kafka-webview-ui/src/main/java/org/sourcelab/kafka/webview/ui/manager/kafka/dto/ApiErrorCause.java

@@ -0,0 +1,83 @@
+/**
+ * MIT License
+ *
+ * Copyright (c) 2017, 2018 SourceLab.org (https://github.com/Crim/kafka-webview/)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.sourcelab.kafka.webview.ui.manager.kafka.dto;
+
+/**
+ * Underlying causes for Api Error.
+ */
+public class ApiErrorCause {
+    private final String type;
+    private final String message;
+    private final String file;
+    private final String method;
+    private final int line;
+
+    /**
+     * Constructor.
+     * @param type Classname of exception.
+     * @param message Error msg.
+     * @param file File the exception was generated from.
+     * @param method Method the exception was generated from.
+     * @param line line number the exception was generated from.
+     */
+    public ApiErrorCause(final String type, final String message, final String file, final String method, final int line) {
+        this.type = type;
+        this.message = message;
+        this.file = file;
+        this.method = method;
+        this.line = line;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public String getFile() {
+        return file;
+    }
+
+    public String getMethod() {
+        return method;
+    }
+
+    public int getLine() {
+        return line;
+    }
+
+    @Override
+    public String toString() {
+        return "ApiErrorCause{"
+            + "type='" + type + '\''
+            + ", message='" + message + '\''
+            + ", file='" + file + '\''
+            + ", method='" + method + '\''
+            + ", line=" + line
+            + '}';
+    }
+}

kafka-webview-ui/src/main/java/org/sourcelab/kafka/webview/ui/manager/kafka/dto/ApiErrorResponse.java

@@ -24,20 +24,26 @@
 
 package org.sourcelab.kafka.webview.ui.manager.kafka.dto;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
 /**
  * Represents an error returned over the API.
  */
 public class ApiErrorResponse {
     private final boolean error = true;
     private final String message;
     private final String requestType;
+    private final ApiErrorCause[] causes;
 
     /**
      * Constructor.
      */
-    public ApiErrorResponse(final String requestType, final String message) {
+    public ApiErrorResponse(final String requestType, final String message, final ApiErrorCause[] causes) {
         this.message = message;
         this.requestType = requestType;
+        this.causes = causes;
     }
 
     public boolean isError() {
@@ -52,12 +58,55 @@ public String getRequestType() {
         return requestType;
     }
 
+    public ApiErrorCause[] getCauses() {
+        return causes;
+    }
+
     @Override
     public String toString() {
         return "ApiErrorResponse{"
             + "error=" + error
             + ", message='" + message + '\''
             + ", requestType='" + requestType + '\''
+            + ", causes=" + Arrays.toString(causes)
             + '}';
     }
+
+    /**
+     * Utility method to generate underlying ApiErrorCause array from exception.
+     * @param exception exception.
+     * @return Array of ApiErrorCauses.
+     */
+    public static ApiErrorCause[] buildCauseList(final Exception exception) {
+        if (exception == null) {
+            return new ApiErrorCause[0];
+        }
+
+        final List<ApiErrorCause> causeList = new ArrayList<>();
+        Throwable cause = exception.getCause();
+        while (cause != null) {
+            final StackTraceElement[] trace = cause.getStackTrace();
+            String file = "";
+            String method = "";
+            int line = 0;
+
+            if (trace.length > 0) {
+                file = trace[0].getFileName();
+                method = trace[0].getClassName() + "::" + trace[0].getMethodName();
+                line = trace[0].getLineNumber();
+            }
+
+            causeList.add(new ApiErrorCause(
+                cause.getClass().getName(),
+                cause.getMessage(),
+                file,
+                method,
+                line
+            ));
+
+            // Continue loop.
+            cause = cause.getCause();
+        }
+        return causeList.toArray(new ApiErrorCause[0]);
+    }
 }