add formatResponse option

README.md

@@ -75,11 +75,16 @@ The `graphqlHTTP` function accepts the following options:
     function from [`GraphQL.js/src/execute.js`](https://github.com/graphql/graphql-js/blob/master/src/execution/execute.js#L122). If `context` is not provided, the
     `request` object is passed as the context.
 
-  * **`pretty`**: If `true`, any JSON response will be pretty-printed.
+  * **`pretty`**: If `true`, any JSON response will be pretty-printed. When set to `true`, this will override `formatResponse` option.
 
   * **`formatError`**: An optional function which will be used to format any
     errors produced by fulfilling a GraphQL operation. If no function is
-    provided, GraphQL's default spec-compliant [`formatError`][] function will be used.
+    provided, GraphQL's default spec-compliant [`formatError`][] function will be used.π
+
+  * **`formatResponse`**: An optional string value to customize the response format. Valid options are:
+    `result`, `pretty`, or `json`. The default value is `json`. When specifying `result`, the result data will
+    be returned instead of output. Otherwise both `json` and `pretty` will output the appropriate
+    response as plain or pretty json respectively.
 
   * **`extensions`**: An optional function for adding additional metadata to the
     GraphQL response as a key-value object. The result will be added to

src/index.js

@@ -63,6 +63,13 @@ export type OptionsData = {
    */
   pretty?: ?boolean,
 
+  /**
+   * A string to configure the format of the output.
+   * Options: result, pretty, or json
+   * Defaults to: json
+   */
+  formatResponse?: ?string,
+
   /**
    * An optional function which will be used to format any errors produced by
    * fulfilling a GraphQL operation. If no function is provided, GraphQL's
@@ -119,7 +126,7 @@ export type RequestInfo = {
   result: ?mixed,
 };
 
-type Middleware = (request: $Request, response: $Response) => Promise<void>;
+type Middleware = (request: $Request, response: $Response) => Promise<mixed>;
 
 /**
  * Middleware for express; takes an options object or function as input to
@@ -135,11 +142,11 @@ function graphqlHTTP(options: Options): Middleware {
     // Higher scoped variables are referred to at various stages in the
     // asynchronous state machine below.
     let params;
-    let pretty;
     let formatErrorFn;
     let extensionsFn;
     let showGraphiQL;
     let query;
+    let formatResponse;
 
     let documentAST;
     let variables;
@@ -176,9 +183,15 @@ function graphqlHTTP(options: Options): Middleware {
         const context = optionsData.context || request;
         const rootValue = optionsData.rootValue;
         const graphiql = optionsData.graphiql;
-        pretty = optionsData.pretty;
+
         formatErrorFn = optionsData.formatError;
         extensionsFn = optionsData.extensions;
+        formatResponse = optionsData.formatResponse || 'json';
+
+        // Backwards compatability
+        if (optionsData.pretty === true) {
+          formatResponse = 'pretty';
+        }
 
         let validationRules = specifiedRules;
         if (optionsData.validationRules) {
@@ -321,15 +334,19 @@ function graphqlHTTP(options: Options): Middleware {
           throw httpError(500, 'Internal Error');
         }
 
-        // If "pretty" JSON isn't requested, and the server provides a
-        // response.json method (express), use that directly.
-        // Otherwise use the simplified sendResponse method.
-        if (!pretty && typeof response.json === 'function') {
-          response.json(result);
-        } else {
-          const payload = JSON.stringify(result, null, pretty ? 2 : 0);
-          sendResponse(response, 'application/json', payload);
+        // Return the correct formatted response
+        if (formatResponse === 'result') {
+          return Promise.resolve(result);
+        }
+        if (formatResponse === 'pretty') {
+          return sendResponse(response, 'application/json', JSON.stringify(result, null, 2));
         }
+        if (typeof response.json === 'function') {
+          return response.json(result);
+        }
+
+        // Default json response
+        return sendResponse(response, 'application/json', JSON.stringify(result, null, 0));
       });
   };
 }