Merge pull request #55 from charanrajtc/added-response-format-option

Add contentType option for passing mandatory type

README.md

@@ -82,6 +82,8 @@ The content type of the response depends on the request's `Accepts` header.
 | debug | Boolean    | `false` | If `true`, HTTP responses include all error properties, including sensitive data such as file paths, URLs and stack traces. See [Example output](#example) below. |
 | log | Boolean | `true` |  If `true`, all errors are printed via `console.error`, including an array of fields (custom error properties) that are safe to include in response messages (both 4xx and 5xx). <br/> If `false`, sends only the error back in the response. |
 | safeFields | [String] | `[]` |  Specifies property names on errors that are allowed to be passed through in 4xx and 5xx responses. See [Safe error fields](#safe-error-fields) below. |
+| defaultType | String | `"json"` | Specify the default response content type to use when the client does not provide any Accepts header.
+| negotiateContentType | Boolean | true | Negotiate the response content type via Accepts request header. When disabled, strong-error-handler will always use the default content type when producing responses. Disabling content type negotiation is useful if you want to see JSON-formatted error responses in browsers, because browsers usually prefer HTML and XML over other content types.
 
 ### Customizing log format
 

lib/content-negotiation.js

@@ -56,6 +56,18 @@ function negotiateContentProducer(req, logWarning, options) {
   debug('Resolved content-type', resolvedContentType);
   var contentType = resolvedContentType || defaultType;
 
+  if (options.negotiateContentType === false) {
+    if (SUPPORTED_TYPES.indexOf(options.defaultType) > -1) {
+      debug('Forcing options.defaultType `%s`',
+        options.defaultType);
+      contentType = options.defaultType;
+    } else {
+      debug('contentType: `%s` is not supported, ' +
+        'falling back to contentType: `%s`',
+         options.defaultType, contentType);
+    }
+  }
+
   // to receive _format from user's url param to overide the content type
   // req.query (eg /api/Users/1?_format=json will overide content negotiation
   // https://github.com/strongloop/strong-remoting/blob/ac3093dcfbb787977ca0229b0f672703859e52e1/lib/http-context.js#L643-L645

test/handler.test.js

@@ -628,6 +628,41 @@ describe('strong-error-handler', function() {
         .expect('Content-Type', /^application\/json/, done);
     });
 
+    it('disables content-type negotiation when negotiateContentType=false',
+      function(done) {
+        givenErrorHandlerForError(new Error('Some error'), {
+          negotiateContentType: false,
+          defaultType: 'application/json',
+        });
+        request.get('/')
+          .set('Accept', 'text/html')
+          .expect('Content-Type', /^application\/json/, done);
+      }
+    );
+
+    it('chooses resolved type when negotiateContentType=false + not-supported',
+      function(done) {
+        givenErrorHandlerForError(new Error('Some error'), {
+          negotiateContentType: false,
+          defaultType: 'unsupported/type',
+        });
+        request.get('/')
+          .set('Accept', 'text/html')
+          .expect('Content-Type', /^text\/html/, done);
+      }
+    );
+
+    it('chooses default type when negotiateContentType=false + not-supported ',
+      function(done) {
+        givenErrorHandlerForError(new Error('Some error'), {
+          negotiateContentType: false,
+          defaultType: 'unsupported/type',
+        });
+        request.get('/')
+          .expect('Content-Type', /^application\/json/, done);
+      }
+    );
+
     it('honors order of accepted content-types of text/html', function(done) {
       givenErrorHandlerForError(new Error('Some error'), {
         defaultType: 'application/json',