graphql-compose

graphql-compose – provides a type registry with a bunch of methods for programmatic schema construction. It allows not only to extend types but also remove fields, interfaces, args. If you want to write your graphql schema generator – graphql-compose is a good instrument for you.

provides methods for editing GraphQL output/input types (add/remove fields/args/interfaces)
introduces Resolvers – the named graphql fieldConfigs, which can be used for finding, updating, removing records
provides an easy way for creating relations between types via Resolvers
provides converter from OutputType to InputType
provides projection parser from AST
provides GraphQL schema language for defining simple types
adds additional types Date, Json

And a little bit more

graphql-compose-[plugin] – are declarative generators/plugins built on top of graphql-compose, which take some ORMs, schema definitions and create GraphQL Models from them or modify existing GraphQL Types.

Type generators built on top `graphql-compose`

graphql-compose-json - generates GraphQL type from JSON (a good helper for wrapping REST APIs)
graphql-compose-mongoose - generates GraphQL types from mongoose (MongoDB models) with Resolvers.
graphql-compose-elasticsearch - generates GraphQL types from elastic mappings; ElasticSearch REST API proxy via GraphQL.
graphql-compose-aws - expose AWS Cloud API via GraphQL

Utility plugins:

graphql-compose-relay - reassemble GraphQL types with Relay specific things, like Node type and interface, globalId, clientMutationId.
graphql-compose-connection - generates connection Resolver from findMany and count Resolvers.
graphql-compose-dataloader - adds DataLoader to graphql-composer resolvers.

Documentation

graphql-compose.github.io

Live Demos

graphql-compose.herokuapp.com - Live demo of GraphQL Server (9 models, 14 files, ~750 LOC)
nodkz.github.io/relay-northwind - Live demo of Relay client working with the server above (8 crazy pages, 47 files, ~3000 LOC)

Examples

Please follow Quick Start Guide for the complete example.

Here is just a demo of ambiguity ways of types definitions:

import { schemaComposer} from 'graphql-compose';

// You may use SDL format for type definition
const CityTC = schemaComposer.createObjectTC(`
  type City {
    code: String!
    name: String!
    population: Number
    countryCode: String
    tz: String
  }
`);

// Define type via Config object
const CountryTC = schemaComposer.createObjectTC({
  name: 'Country',
  fields: {
    title: 'String',
    geo: `type LonLat { lon: Float, lat: Float }`,
    hoisting: {
      type: () => AnotherTC,
      description: `
        You may wrap type in thunk for solving
        hoisting problems when two types cross reference
        each other.
      `,
    }
  }
});

// Or via declarative methods define some additional fields
CityTC.addFields({
  country: CountryTC, // some another Type
  ucName: { // standard GraphQL like field definition
    type: GraphQLString,
    resolve: (source) => source.name.toUpperCase(),
  },
  currentLocalTime: { // extended GraphQL Compose field definition
    type: 'Date',
    resolve: (source) => moment().tz(source.tz).format(),
    projection: { tz: true }, // load `tz` from database, when requested only `localTime` field
  },
  counter: 'Int', // shortening for only type definition for field
  complex: `type ComplexType {
    subField1: String
    subField2: Float
    subField3: Boolean
    subField4: ID
    subField5: JSON
    subField6: Date
  }`,
  list0: {
    type: '[String]',
    description: 'Array of strings',
  },
  list1: '[String]',
  list2: ['String'],
  list3: [new GraphQLOutputType(...)],
  list4: [`type Complex2Type { f1: Float, f2: Int }`],
});

// Add resolver method
CityTC.addResolver({
  kind: 'query',
  name: 'findMany',
  args: {
    filter: `input CityFilterInput {
      code: String!
    }`,
    limit: {
      type: 'Int',
      defaultValue: 20,
    },
    skip: 'Int',
    // ... other args if needed
  },
  type: [CityTC], // array of cities
  resolve: async ({ args, context }) => {
    return context.someCityDB
      .findMany(args.filter)
      .limit(args.limit)
      .skip(args.skip);
  },
});

// Remove `tz` field from schema
CityTC.removeField('tz');

// Add description to field
CityTC.extendField('name', {
  description: 'City name',
});

schemaComposer.Query.addFields({
  cities: CityTC.getResolver('findMany'),
  currentTime: {
    type: 'Date',
    resolve: () => Date.now(),
  },
});

schemaComposer.Mutation.addFields({
  createCity: CityTC.getResolver('createOne'),
  updateCity: CityTC.getResolver('updateById'),
  ...adminAccess({
    removeCity: CityTC.getResolver('removeById'),
  }),
});

function adminAccess(resolvers) {
  Object.keys(resolvers).forEach(k => {
    resolvers[k] = resolvers[k].wrapResolve(next => rp => {
      // rp = resolveParams = { source, args, context, info }
      if (!rp.context.isAdmin) {
        throw new Error('You should be admin, to have access to this action.');
      }
      return next(rp);
    });
  });
  return resolvers;
}

// construct schema which can be passed to express-graphql, apollo-server or graphql-yoga
export const schema = schemaComposer.buildSchema();