graphql-compose

What is graphql-compose?

graphql-compose is a toolkit for generating and working with GraphQL schemas in a more flexible and composable way. It provides utilities to create GraphQL types, resolvers, and schemas with ease, allowing for a more modular and maintainable approach to building GraphQL APIs.

What are graphql-compose's main functionalities?

Schema Creation

This feature allows you to create a GraphQL schema by adding fields to the Query type. The example demonstrates adding a simple 'hello' field that returns a string.

const { schemaComposer } = require('graphql-compose');

schemaComposer.Query.addFields({
  hello: {
    type: 'String',
    resolve: () => 'Hello, world!',
  },
});

const schema = schemaComposer.buildSchema();

Type Composers

Type Composers allow you to define GraphQL object types and their fields in a modular way. The example shows how to create a 'User' type and add a custom resolver to it.

const { schemaComposer } = require('graphql-compose');

const UserTC = schemaComposer.createObjectTC({
  name: 'User',
  fields: {
    id: 'ID!',
    name: 'String',
  },
});

UserTC.addResolver({
  name: 'findById',
  type: 'User',
  args: { id: 'ID!' },
  resolve: ({ source, args, context, info }) => {
    // resolver logic here
  },
});

Resolver Composition

Resolver Composition allows you to add multiple resolvers to a type, making it easier to manage complex query logic. The example shows how to add 'findById' and 'findByName' resolvers to the 'User' type.

const { schemaComposer } = require('graphql-compose');

const UserTC = schemaComposer.getOrCreateOTC('User', {
  fields: {
    id: 'ID!',
    name: 'String',
  },
});

UserTC.addResolver({
  name: 'findById',
  type: UserTC,
  args: { id: 'ID!' },
  resolve: ({ source, args, context, info }) => {
    // resolver logic here
  },
});

UserTC.addResolver({
  name: 'findByName',
  type: UserTC,
  args: { name: 'String' },
  resolve: ({ source, args, context, info }) => {
    // resolver logic here
  },
});

Other packages similar to graphql-compose

graphql-tools

graphql-tools is a set of utilities from Apollo for creating and manipulating GraphQL schemas. It provides schema stitching, schema delegation, and other advanced features. Compared to graphql-compose, graphql-tools is more focused on schema stitching and merging, while graphql-compose offers a more composable and modular approach to schema and resolver creation.

type-graphql

type-graphql is a library that allows you to define your GraphQL schema using TypeScript classes and decorators. It provides a more type-safe approach to schema creation compared to graphql-compose, which is more flexible and JavaScript-centric. type-graphql is ideal for TypeScript users who want to leverage decorators and strong typing.

nexus

nexus is a code-first GraphQL schema construction library for TypeScript and JavaScript. It allows you to define your schema using a fluent API and integrates well with the Prisma ORM. Compared to graphql-compose, nexus offers a more opinionated and integrated approach, especially when used with Prisma, while graphql-compose provides more flexibility and composability.

README

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();

Contributors

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License

MIT