graphql-ext-js

GraphQL extensions and toolkit for JS.

Install

npm i graphql-ext

Examples

See examples.

express

const express = require('express');
const {specifiedRules: rules} = require('graphql');
const {graphql} = require('graphql-ext/http');
const {schema, rootValue} = require('./schema');

function main() {
  const app = express();
  app.use(express.json());
  app.post(
    '/graphql',
    graphql({
      schema,
      rootValue,
      rules,
      parseParams: async (req) => req.body,
      context: (req) => req.headers['x-user'],
    }),
  );
  app.listen(4000, () =>
    console.info('Running a GraphQL API at http://localhost:4000/graphql'),
  );
}

main();

validation

directive @length(
  min: Int
  max: Int
  message: String
) on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION

type Query {
  hello(name: String! @length(min: 2, max: 10)): String!
}

const {specifiedRules} = require('graphql');
const {inputValidationDirectiveRule} = require('graphql-ext/validation');
const {length} = require('graphql-ext/validation/rules');

app.post(
  '/graphql',
  graphql({
    // ...
    rules: [
      ...specifiedRules,
      inputValidationDirectiveRule({
        entries: [['length', length]],
      }),
    ],
  }),
);

relay

directive @range(
  min: Int
  max: Int
  message: String
) on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION

type Query {
  numbers(
    first: Int @range(min: 1, max: 15)
    after: String
    last: Int @range(min: 1, max: 15)
    before: String
  ): NumberConnection!
}

type NumberConnection {
  edges: [NumberEdge!]!
  pageInfo: PageInfo!
  totalCount: Int!
}

type NumberEdge {
  cursor: String!
  node: Int!
}

type PageInfo {
  endCursor: String!
  hasNextPage: Boolean!
  hasPreviousPage: Boolean!
  startCursor: String!
}

const {CursorConnection} = require('graphql-ext/relay');
const {addResolvers} = require('graphql-ext/misc');

// ...
const items = Array.from({length: 20}).map((_, i) => i);
const cc = new CursorConnection('numbers:');
const resolvers = {
  Query: {
    numbers: (parent, args) => cc.fromArray(items, args),
  },
};
addResolvers(schema, resolvers);

offset paging:

const service = {
  countNumbers: async () => items.length,
  listNumbers: async ({offset, limit}) => items.slice(offset, offset + limit),
};

const resolvers = {
  Query: {
    numbers: async (parent, args) => {
      const totalCount = await service.countNumbers();
      const [offset, limit] = cc.toOffsetPaging(args, totalCount);
      const items = await service.listNumbers({offset, limit});
      return cc.fromSlice(items, offset, totalCount);
    },
  },
};

subscription

Subscription returns ndjson stream.

type Subscription {
  countdown(initial: Int! = 2): Int
}

const resolvers = {
  Subscription: {
    countdown: {
      async *subscribe(_, {initial}) {
        for (let i = initial; i >= 0; i--) {
          await new Promise((resolve) => setTimeout(resolve, 500));
          yield i;
        }
      },
      resolve(value) {
        return value;
      },
    },
  },
};