GraphQL HTTP Server Middleware

Create a GraphQL HTTP server with koa v2. it's ported from express-graphql. koa-graphql-next have the same api with express-graphql, and well tested like express-graphql,that's mean,and could be try to using in product currently.

Faq

1. only supported koa v2
2. add url to options,and default url is '/graphql'
3. using jest and supertest,instead of mocha in express-graphql.all test from express-graphql (now 64 tests),have been rewrited and passed.
4. ported from express-graphql,for the code,"line by line",and rewrites all the test of express-graphql,so fix many bug founded in tests. but,thanks for the author of these project: koa-graphql by chentsulin graffiti it proveder a middleware for koa v1. koa-graphql by Arch-Mage
5. for the detail of usage,could read the test,for example how to upload files with graphql.

Installation

npm install --save koa-graphql-next

Then use koa-graphql-next at any point as a middleware with koa@next:

import graphqlHTTP from 'koa-graphql-next';

const app = new koa();

app.use( graphqlHTTP({
  schema: MyGraphQLSchema,
  graphiql: true
}));

app.listen(3000);

Options

The graphqlHTTP function accepts the following options:

• schema: A GraphQLSchema instance from graphql-js. A schema must be provided.

• context: A value to pass as the context to the graphql() function from graphql-js.

• rootValue: A value to pass as the rootValue to the graphql() function from graphql-js.

• pretty: If true, any JSON response will be pretty-printed.

• 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.

• validationRules: Optional additional validation rules queries must satisfy in addition to those defined by the GraphQL spec.

• graphiql: If true, may present GraphiQL when loaded directly from a browser (a useful tool for debugging and exploration).

• url: added in koa-graphql-next,An optional string for the query url. default value is '/graphql'.

Debugging

During development, it's useful to get more information from errors, such as stack traces. Providing a function to formatError enables this:

formatError: error => ({
  message: error.message,
  locations: error.locations,
  stack: error.stack
})

HTTP Usage

Once installed at a path, koa-graphql-next will accept requests with the parameters:

• query: A string GraphQL document to be executed.

• variables: The runtime values to use for any GraphQL query variables as a JSON object.

• operationName: If the provided query contains multiple named operations, this specifies which operation should be executed. If not provided, a 400 error will be returned if the query contains multiple named operations.

• raw: If the graphiql option is enabled and the raw parameter is provided raw JSON will always be returned instead of GraphiQL even when loaded from a browser.

GraphQL will first look for each parameter in the URL's query-string:

/graphql?query=query+getUser($id:ID){user(id:$id){name}}&variables={"id":"4"}

If not found in the query-string, it will look in the POST request body.

If a previous middleware has already parsed the POST body, the ctx.request.body value will be used. Use [koa-multer][] or a similar middleware to add support for multipart/form-data content, which may be useful for GraphQL mutations involving uploading files.

If the POST body has not yet been parsed, koa-graphql-next will interpret it depending on the provided Content-Type header.

• application/json: the POST body will be parsed as a JSON object of parameters.

• application/x-www-form-urlencoded: this POST body will be parsed as a url-encoded string of key-value pairs.

• application/graphql: The POST body will be parsed as GraphQL query string, which provides the query parameter.