Allow custom graphql params extraction from request

src/__tests__/http-test.ts

@@ -1029,6 +1029,36 @@ function runTests(server: Server) {
     });
   });
 
+  it('allow custom graphql params extraction from request', async () => {
+    const app = server();
+
+    app.get(
+      urlString(),
+      graphqlHTTP(
+        {
+          schema: TestSchema,
+        },
+        (request) => {
+          const searchParams = new URLSearchParams(request.url.split('?')[1]);
+          return {
+            query: searchParams.get('graphqlQuery'),
+            variables: null,
+            operationName: null,
+            raw: false,
+          };
+        },
+      ),
+    );
+
+    const response = await app.request().get(
+      urlString({
+        graphqlQuery: '{test}',
+      }),
+    );
+
+    expect(response.text).to.equal('{"data":{"test":"Hello World"}}');
+  });
+
   describe('Pretty printing', () => {
     it('supports pretty printing', async () => {
       const app = server();

src/index.ts

@@ -195,7 +195,16 @@ type Middleware = (request: Request, response: Response) => Promise<void>;
  * Middleware for express; takes an options object or function as input to
  * configure behavior, and returns an express middleware.
  */
-export function graphqlHTTP(options: Options): Middleware {
+export function graphqlHTTP(
+  options: Options,
+  /**
+   * An optional function which will get params from request instead of
+   * default getGraphQLParams
+   */
+  customGraphQLParamsFn?: (
+    request: Request,
+  ) => GraphQLParams | Promise<GraphQLParams>,
+): Middleware {
   devAssert(options != null, 'GraphQL middleware requires options.');
 
   return async function graphqlMiddleware(
@@ -210,11 +219,12 @@ export function graphqlHTTP(options: Options): Middleware {
     let pretty = false;
     let result: ExecutionResult;
     let optionsData: OptionsData | undefined;
+    const graphQLParamsFn = customGraphQLParamsFn ?? getGraphQLParams;
 
     try {
       // Parse the Request to get GraphQL request parameters.
       try {
-        params = await getGraphQLParams(request);
+        params = await graphQLParamsFn(request);
       } catch (error: unknown) {
         // When we failed to parse the GraphQL parameters, we still need to get
         // the options object, so make an options call to resolve just that.