• GraphQL Genie Subscriptions
  • Installation
  • Enable plugin
  • Subscription API
  • Examples
  • Thanks/Credit

GraphQL Genie Subscriptions

Pass in a pubsub object from graphql-subscriptions and the necessary types and resolvers will be added to your schema

Installation

Assuming you already have GraphQL Genie installed.

npm install graphql-genie-subscriptions graphql-subscriptions

or

yarn add graphql-genie-subscriptions graphql-subscriptions

Enable plugin

import { FortuneOptions, GraphQLGenie } from 'graphql-genie';
import subscriptionPlugin from 'graphql-genie-subscriptions';
import { PubSub } from 'graphql-subscriptions';

const genie = new GraphQLGenie(...args);

// or you could pass in to the constructor as part of the plugins variable
genie.use(subscriptionPlugin(new PubSub())); 

//get the GraphQLSchema and use it with any other tools you need, such as subscriptions-transport-ws
//always call getSchema after .use
const schema = genie.getSchema();

Subscription API

Given you passed the following schema to Graphql Genie

type Post {
  id: ID! @unique
	title: String!
	text: String
	author: User @relation(name: "posts")
}

type User {
	id: ID! @unique
	displayname: String @unique
	email: String! @unique
	name : String 
	posts: [Post] @relation(name: "posts")
}

2 Subscriptions will be created, user and post.

Each will have a where input and a payload output

user(
	where: UserSubscriptionWhereInput
): UserSubscriptionPayload

The where input type looks like

type UserSubscriptionWhereInput {
	AND: [UserSubscriptionWhereInput!]
	OR: [UserSubscriptionWhereInput!]
	mutation_in: [MutationType!]
	updatedFields_contains: [String!]
	updatedFields_contains_every: [String!]
	node: UserWhereInput
}

• mutation_in: Select which mutations you want to subscribe to (MutationType is CREATED, UPDATED or DELETED)
• updatedFields_contains: Matches if any of the fields specified have been updated.
• updatedFields_contains_every: Matches if all fields specified have been updated.
• node: To select specific nodes that you want to be notified about. The WhereInput is the same one used in other Queries and Mutations for this node

The payload output looks like

type UserSubscriptionPayload {
	mutation: MutationType!
	node: User
	updatedFields: [String!]
	previousValues: UserPreviousValues
}

• mutation: Which mutation happened

• node: Information on the mutated node.

• updatedFields: In case of an update, a list of the fields that changed.

• previousValues: In case of an update, previous values of the node. Scalars return the actual value but other output types return just the id(s)

type UserPreviousValues {
	id: ID!
	displayname: String
	email: String!
	name: String
	posts_ids: [String!]
}

Examples

All the graphql-yoga code examples use the subscriptions plugin.

The tests are a good place to see example subscription queries.

Thanks/Credit

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