bhanditz/graphql-compose

Toolkit for generating complex GraphQL Schemas on Node.js

GraphQL-compose

GraphQL – is a query language for APIs. graphql-js is the reference implementation of GraphQL for nodejs which introduce GraphQL type system for describing schema (definition over configuration) and executes queries on the server side. express-graphql is a HTTP server which gets request data, passes it to graphql-js and returned result passes to response.

graphql-compose – the imperative tool which worked on top of graphql-js. It provides some methods for creating types and GraphQL Models (so I call types with a list of common resolvers) for further building of complex relations in your schema.

• 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

graphql-compose-[plugin] – is a declarative generators/plugins that build on top of graphql-compose, which take some ORMs, schema definitions and creates GraphQL Models from them or modify existed GraphQL Types.

Type generator plugins:

• 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 - add DataLoader to graphql-composer resolvers.
• graphql-compose-recompose - utility that wrap GraphQL compose to high order functional pattern [work in process].

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)

Example

city.js

import { TypeComposer} from 'graphql-compose';
import { CountryTC } from './country';

export const CityTC = TypeComposer.create(`
  type City {
    code: String!
    name: String!
    population: Number
    countryCode: String
    tz: String
  }
`);

// Define some additional fields
CityTC.addFields({
  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);
  },
});

// Add relation between City and Country by `countryCode` field.
CityTC.addRelation( // GraphQL relation definition
  'country',
  {
    resolver: () => CountryTC.getResolver('findOne'),
    prepareArgs: {
      filter: source => ({ code: `${source.countryCode}` }),
    },
    projection: { countryCode: true },
  }
);

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

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

schema.js

import { schemaComposer } from 'graphql-compose';
import { CityTC } from './city';
import { CountryTC } from './country';

schemaComposer.Query.addFields({
  cities: CityTC.getResolver('findMany'),
  country: CountryTC.getResolver('findOne'),
  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;
}

export default schemaComposer.buildSchema();

License

MIT