graphql-http

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GraphQL request handler compliant with GraphQL-over-HTTP specification

Features

  • GraphQL-over-HTTP specification compliant
  • application/graphql-response+json support
  • Universal

Example

A simple example of creating a GraphQL server and GraphQL client.

std/http + graphql.js

server:

import {
  createHandler,
} from "https://deno.land/x/graphql_http@$VERSION/mod.ts";
import { serve } from "https://deno.land/std@$VERSION/http/mod.ts";
import { buildSchema } from "https://esm.sh/graphql@$VERSION";

const schema = buildSchema(`type Query {
    greet: String!
  }`);
const handler = createHandler(schema, {
  rootValue: {
    greet: "hello world!",
  },
});

serve(handler);

It is recommended to use graphql-request as the GraphQL client.

client:

import { gql, gqlFetch } from "https://deno.land/x/gql_request@$VERSION/mod.ts";

const document = gql`query { greet }`;
const { data, errors, extensions } = await gqlFetch("<ENDPOINT>", document);

Spec

This project is implemented in accordance with GraphQL-over-HTTP specification.

We are actively implementing IETF RFC 2119 SHOULD and RECOMMENDED.

Request Parameters

A GraphQL-over-HTTP request is formed of the following parameters:

Name Required Description
query :white_check_mark: A Document containing GraphQL Operations and Fragments to execute. Must be a string.
operationName - The name of the Operation in the Document to execute.
GET: If present, must be a string.
variables - Values for any Variables defined by the Operation.
GET: If present, must be represented as a URL-encoded JSON string.

Response Status

The following responses may be returned.

Status Condition
200 If GraphQL is actually executed, even if it contains Field errors.
400 A required parameter does not exist. Illegal format of parameter.
405 When a mutation or subscription operation is requested on GET request.
406 The client Accept HTTP header does not contain at least one of the supported media types.
415 The client Content-type HTTP header does not contain at least one of the supported media types.
500 If the server encounters an unexpected error.

Below are the specific conditions under which each may occur. Errors are classified into four major categories.

  • HTTP Request errors
  • (GraphQL) Request errors
  • (GraphQL) Field errors
  • Unknown errors

HTTP Request errors

HTTP Request errors are errors in the http protocol. This refers to errors that can occur between HTTP and GraphQL, such as missing/incorrect values for required parameters, missing/incorrect values for required headers, etc.

Since these are client-side errors, the appropriate 4XX status is returned.

Request errors

Request errors are defined at [GraphQL Spec] 7.Response - Request errors.

Note here that the status code may be different depending on the Content-Type.

application/json

If Content-Type is application/json, all results of GraphQL Requests including GraphQL validation will be treated as 200 status.

See the [GraphQL over HTTP 6.4.1] application/json#Note for the reason for this.

application/graphql+json

If Content-Type is application/graphql-response+json, it is possible to respond with a status code other than 200 depending on the result of the GraphQL Request.

If the GraphQL request is invalid (e.g. it is malformed, or does not pass validation) then the response with 400 status code.

Field errors

Field errors are defined at [GraphQL Spec 7.Response] - Field errors.

Even if a Field error occurs, it will always be a 200 status code.

Unknown errors

If an error other than the above occurs on the server side, a 500 status code will be responded.

Upgrade to application/graphql-response+json

As you may have noticed, application/graphql-response+json represents a more accurate semantics response.

If you want application/graphql-response+json content, you must put application/graphql-response+json as a higher priority than application/json in the Accept header.

Example: Accept: application/graphql-response+json,application/json.

application/graphql-response+json vs application/json

Response status

application/graphql+json application/json
HTTP Request error 4XX(eg.406, 415) 4XX
GraphQL request error 400 200
GraphQL field error 200 200
Unknown(Internal server) error 5XX 5XX

Where the subscription?

Unfortunately, there is currently no specification for subscription and it is not implemented.

You can refer to other projects' implementations using SSE or Websocket.

Recipes

License

Copyright © 2022-present graphqland.

Released under the MIT license