Add support for customParseFn option

README.md

@@ -97,6 +97,9 @@ The `graphqlHTTP` function accepts the following options:
     errors produced by fulfilling a GraphQL operation. If no function is
     provided, GraphQL's default spec-compliant [`formatError`][] function will be used.
 
+  * **`customParseFn`**: An optional function which will be used to create a document
+    instead of the default `parse` from `graphql-js`.
+
   * **`formatError`**: is deprecated and replaced by `customFormatErrorFn`. It will be
     removed in version 1.0.0.
 

src/__tests__/http-test.js

@@ -28,8 +28,10 @@ import {
   GraphQLString,
   GraphQLError,
   BREAK,
+  Source,
   validate,
   execute,
+  parse,
 } from 'graphql';
 import graphqlHTTP from '../';
 
@@ -2032,6 +2034,56 @@ describe('test harness', () => {
       });
     });
 
+    describe('Custom parse function', () => {
+      it('can replace default parse functionality', async () => {
+        const app = server();
+
+        let seenParseArgs;
+
+        get(
+          app,
+          urlString(),
+          graphqlHTTP(() => {
+            return {
+              schema: TestSchema,
+              customParseFn(args) {
+                seenParseArgs = args;
+                return parse(new Source('{test}', 'Custom parse function'));
+              },
+            };
+          }),
+        );
+
+        const response = await request(app).get(urlString({ query: '----' }));
+
+        expect(response.status).to.equal(200);
+        expect(response.text).to.equal('{"data":{"test":"Hello World"}}');
+        expect(seenParseArgs).property('body', '----');
+      });
+      it('can throw errors', async () => {
+        const app = server();
+        get(
+          app,
+          urlString(),
+          graphqlHTTP(() => {
+            return {
+              schema: TestSchema,
+              customParseFn() {
+                throw new GraphQLError('my custom parse error');
+              },
+            };
+          }),
+        );
+
+        const response = await request(app).get(urlString({ query: '----' }));
+
+        expect(response.status).to.equal(400);
+        expect(response.text).to.equal(
+          '{"errors":[{"message":"my custom parse error"}]}',
+        );
+      });
+    });
+
     describe('Custom result extensions', () => {
       it('allows for adding extensions', async () => {
         const app = server();

src/index.js

@@ -104,6 +104,12 @@ export type OptionsData = {
    */
   customFormatErrorFn?: ?(error: GraphQLError) => mixed,
 
+  /**
+   * An optional function which will be used to create a document instead of
+   * the default `parse` from `graphql-js`.
+   */
+  customParseFn?: ?(source: Source) => DocumentNode,
+
   /**
    * `formatError` is deprecated and replaced by `customFormatErrorFn`. It will
    *  be removed in version 1.0.0.
@@ -186,6 +192,7 @@ function graphqlHTTP(options: Options): Middleware {
     let formatErrorFn = formatError;
     let validateFn = validate;
     let executeFn = execute;
+    let parseFn = parse;
     let extensionsFn;
     let showGraphiQL;
     let query;
@@ -265,11 +272,11 @@ function graphqlHTTP(options: Options): Middleware {
         }
 
         //  GraphQL source.
-        const source = new Source(query, 'GraphQL request');
+        const source = new Source(query);
 
         // Parse source to AST, reporting any syntax error.
         try {
-          documentAST = parse(source);
+          documentAST = parseFn(source);
         } catch (syntaxError) {
           // Return 400: Bad Request if any syntax errors errors exist.
           response.statusCode = 400;
@@ -418,6 +425,7 @@ function graphqlHTTP(options: Options): Middleware {
 
         validateFn = optionsData.customValidateFn || validateFn;
         executeFn = optionsData.customExecuteFn || executeFn;
+        parseFn = optionsData.customParseFn || parseFn;
         formatErrorFn =
           optionsData.customFormatErrorFn ||
           optionsData.formatError ||