Introduction to graphql-compose

GraphQL is a powerful tool for API development, and graphql-compose enhances its capabilities by offering a more fluid and flexible way to build complex schemas. Whether you’re developing a small app or a large-scale platform, graphql-compose equips you with the tools needed to streamline your GraphQL workflows.

Getting Started with graphql-compose

  import { SchemaComposer } from 'graphql-compose'
  const schemaComposer = new SchemaComposer()

Creating Types

With graphql-compose, you can easily create GraphQL types using a schema composer.

  const UserType = schemaComposer.createObjectTC({
    name: 'User',
    fields: {
      id: 'ID',
      name: 'String',
      age: 'Int',
    },
  })

Adding Resolvers

Resolvers define how to fetch the data associated with a type.

  UserType.addResolver({
    name: 'findById',
    type: UserType,
    args: { id: 'ID!' },
    resolve: async ({ args }) => {
      return await Users.findById(args.id)
    },
  })

Combining GraphQL with a REST API

It can also integrate seamlessly with existing REST APIs, enabling the creation of a unified data layer.

  const PostType = schemaComposer.createObjectTC({
    name: 'Post',
    fields: {
      id: 'ID',
      title: 'String',
      body: 'String',
    },
  })

  UserType.addRelation('posts', {
    resolver: () => PostType.getResolver('findMany'),
    prepareArgs: {
      _ids: (source) => source.postIds,
    },
    projection: { postIds: true },
  })

Complete Example

Here’s a complete example of a small app using graphql-compose.

  import { SchemaComposer } from 'graphql-compose'
  const schemaComposer = new SchemaComposer()

  const UserType = schemaComposer.createObjectTC({
    name: 'User',
    fields: {
      id: 'ID',
      name: 'String',
      age: 'Int',
    },
  })

  const PostType = schemaComposer.createObjectTC({
    name: 'Post',
    fields: {
      id: 'ID',
      title: 'String',
      body: 'String',
    },
  })

  UserType.addResolver({
    name: 'findById',
    type: UserType,
    args: { id: 'ID!' },
    resolve: async ({ args }) => {
      return await Users.findById(args.id)
    },
  })

  UserType.addRelation('posts', {
    resolver: () => PostType.getResolver('findMany'),
    prepareArgs: {
      _ids: (source) => source.postIds,
    },
    projection: { postIds: true },
  })

  schemaComposer.Query.addFields({
    userById: UserType.getResolver('findById'),
  })

  schemaComposer.Mutation.addFields({
    createUser: UserType.getResolver('createOne'),
  })

  const graphqlSchema = schemaComposer.buildSchema()

By leveraging graphql-compose, you can significantly streamline the development process, creating more maintainable and scalable APIs.

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