Mashroom GraphQL Plugin Loader

This plugin adds possibility to define GraphQL services in Mashroom.

Additionally - it bootstraps Apollo Server using Mashroom internal express application. Subscriptions are supported over Web Sockets.

Installation

npm i -S mashroom-graphql-server

Schema stitching

You can have multiple GraphQL Plugins registered on your server. Schemas from different plugins are stitched together as described here schema stitching

Example

To start demo server run

npm i npm run dev

and open localhost:5050/graphql in your browser

You can subscribe to change using

subscription Subscription {
  personCreated {
    id
  }
}

and produce new object running this query

query Test($createPersonId: ID!) {
  createPerson(id: $createPersonId) {
    id
  }
}

after 1500ms delay you should see activity in subscription window

Writing GraphQL Plugins for Mashroom Server

Plugin has to have definition like the example bellow

{
  "name": "Mashroom GraphQL Echo Plugin",
  "type": "mashroom-graphql-plugin",
  "bootstrap": "./dist/bootstrap.js",
  "defaultConfig": {
    "pubSub": "memory"
  }
}

Configuration:

• pubSub - type of pubSub engine: memory or redis. memory does not support cluster environment

Where bootstrap has one default export of the type MashroomGraphQLPluginBootstrapFunction

const bootstrap: MashroomGraphQLPluginBootstrapFunction = (pluginName, config, contextHolder, pubSub) => {
  return Promise.resolve(new TestGraphQLPlugin(pubSub));
}

Bootstrap Parameters:

• pluginName - name of the plugin itself
• config - config provided for the plugin
• contextHolder - holds current context of the plugin
• pubSub - reference to pubSub engine used for subscriptions

Mashroom GraphQL Plugin has to implement following interface

interface MashroomGraphQLPlugin {
  getSchema(): DocumentNode | Array<DocumentNode> | string | Array<string>;
  getResolvers(): IResolvers | Array<IResolvers>;
  getPubSub(): PubSubEngine;
}

• getSchema - returns schema for current plugin
• getResolvers - resolvers for given schema
• getPubSub - returns reference to current pubSub engine

Example:

getSchema(): DocumentNode | Array<DocumentNode> | string | Array<string> {
  return gql`
    type Person {
      id: ID!
    }

    type Query {
      personByName(id: ID!): Person
      createPerson(id: ID!): Person
    }
    
    type Subscription {
      personCreated: Person
    }
  `;
}

getResolvers(): IResolvers | Array<IResolvers> {
    return {
      Query: {
        personByName: (parent, args) => {
          return {
            id: args.id,
          };
        },

        createPerson: (parent, args) => {
          setTimeout(() => {
            this.getPubSub().publish('PERSON_CREATED', {
              personCreated: {
                id: args.id,
              },
            });
          }, 1500);
        },
      },
      Subscription: {
        personCreated: {
          subscribe: () => this.getPubSub().asyncIterator(['PERSON_CREATED']),
        },
      },
    }
  }