Use the application/graphql+json content-type.

See graphql/graphql-over-http#31 .

changelog.md

@@ -5,6 +5,7 @@
 ### Major
 
 - Added a [package `exports` field](https://nodejs.org/api/esm.html#esm_package_entry_points) with [conditional exports](https://nodejs.org/api/esm.html#esm_conditional_exports) to support native ESM in Node.js and keep internal code private, [whilst avoiding the dual package hazard](https://nodejs.org/api/esm.html#esm_approach_1_use_an_es_module_wrapper). Published files have been reorganized, so previously undocumented deep imports will need to be rewritten according to the newly documented paths.
+- Use the `application/graphql+json` content-type instead of `application/json` for GraphQL requests and responses. This content-type [is being standardized](https://github.com/APIs-guru/graphql-over-http/issues/31) in the [GraphQL over HTTP specification](https://github.com/APIs-guru/graphql-over-http).
 
 ### Patch
 

public/errorHandler.js

@@ -101,6 +101,9 @@ module.exports = function errorHandler() {
         ctx.response.status = httpError.status;
       }
 
+      // Set the content-type.
+      ctx.response.type = 'application/graphql+json';
+
       // Support Koa app error listeners.
       ctx.app.emit('error', error, ctx);
     }

public/execute.js

@@ -76,7 +76,11 @@ const ALLOWED_EXECUTE_OPTIONS_OVERRIDE = ALLOWED_EXECUTE_OPTIONS_STATIC.filter(
  *
  * const app = new Koa()
  *   .use(errorHandler())
- *   .use(bodyParser())
+ *   .use(bodyParser({
+ *     extendTypes: {
+ *       json: 'application/graphql+json',
+ *     },
+ *   }))
  *   .use(execute({ schema }));
  * ```
  */
@@ -237,6 +241,9 @@ module.exports = function execute(options) {
       throw error;
     }
 
+    // Set the content-type.
+    ctx.response.type = 'application/graphql+json';
+
     await next();
   };
 };

readme.md

@@ -105,7 +105,13 @@ _A basic GraphQL API._
 >
 > const app = new Koa()
 >   .use(errorHandler())
->   .use(bodyParser())
+>   .use(
+>     bodyParser({
+>       extendTypes: {
+>         json: 'application/graphql+json',
+>       },
+>     })
+>   )
 >   .use(execute({ schema }));
 > ```
 

test/fetchJsonAtPort.js → test/fetchGraphQL.js

@@ -3,20 +3,20 @@
 const fetch = require('node-fetch');
 
 /**
- * Fetches JSON at a given localhost port.
+ * Fetches GraphQL.
  * @kind function
- * @name fetchJsonAtPort
+ * @name fetchGraphQL
  * @param {number} port Localhost port.
  * @param {object} options Fetch options.
  * @returns {Promise<Response>} Fetch response.
  * @ignore
  */
-module.exports = function fetchJsonAtPort(port, options = {}) {
+module.exports = function fetchGraphQL(port, options = {}) {
   return fetch(`http://localhost:${port}`, {
     method: 'POST',
     headers: {
-      'Content-Type': 'application/json',
-      Accept: 'application/json',
+      'Content-Type': 'application/graphql+json',
+      Accept: 'application/graphql+json',
     },
     ...options,
   });

test/public/errorHandler.test.js

@@ -4,7 +4,7 @@ const { deepStrictEqual, ok, strictEqual } = require('assert');
 const createHttpError = require('http-errors');
 const Koa = require('koa');
 const errorHandler = require('../../public/errorHandler');
-const fetchJsonAtPort = require('../fetchJsonAtPort');
+const fetchGraphQL = require('../fetchGraphQL');
 const listen = require('../listen');
 
 module.exports = (tests) => {
@@ -25,9 +25,13 @@ module.exports = (tests) => {
       const { port, close } = await listen(app);
 
       try {
-        const response = await fetchJsonAtPort(port);
+        const response = await fetchGraphQL(port);
 
         strictEqual(koaError, null);
+        strictEqual(
+          response.headers.get('Content-Type'),
+          'application/graphql+json'
+        );
         deepStrictEqual(await response.json(), {
           errors: [{ message: 'Internal Server Error' }],
         });
@@ -54,14 +58,18 @@ module.exports = (tests) => {
     const { port, close } = await listen(app);
 
     try {
-      const response = await fetchJsonAtPort(port);
+      const response = await fetchGraphQL(port);
 
       ok(koaError instanceof Error);
       strictEqual(koaError.name, 'Error');
       strictEqual(koaError.message, 'Message.');
       strictEqual(koaError.status, 500);
       strictEqual(koaError.expose, false);
       strictEqual(response.status, 500);
+      strictEqual(
+        response.headers.get('Content-Type'),
+        'application/graphql+json'
+      );
       deepStrictEqual(await response.json(), {
         errors: [
           {
@@ -90,14 +98,18 @@ module.exports = (tests) => {
     const { port, close } = await listen(app);
 
     try {
-      const response = await fetchJsonAtPort(port);
+      const response = await fetchGraphQL(port);
 
       ok(koaError instanceof Error);
       strictEqual(koaError.name, 'ForbiddenError');
       strictEqual(koaError.message, 'Message.');
       strictEqual(koaError.status, 403);
       strictEqual(koaError.expose, true);
       strictEqual(response.status, 403);
+      strictEqual(
+        response.headers.get('Content-Type'),
+        'application/graphql+json'
+      );
       deepStrictEqual(await response.json(), {
         errors: [
           {
@@ -132,14 +144,18 @@ module.exports = (tests) => {
       const { port, close } = await listen(app);
 
       try {
-        const response = await fetchJsonAtPort(port);
+        const response = await fetchGraphQL(port);
 
         ok(koaError instanceof Error);
         strictEqual(koaError.name, 'Error');
         strictEqual(koaError.message, 'Message.');
         strictEqual(koaError.status, 500);
         strictEqual(koaError.expose, false);
         strictEqual(response.status, 500);
+        strictEqual(
+          response.headers.get('Content-Type'),
+          'application/graphql+json'
+        );
         deepStrictEqual(await response.json(), {
           data: {},
           errors: [