Depricated: Please use https://github.com/n1ru4l/graphql-live-queries instead.
graphql-live-subscriptions
provides RFC6902-compatible JSON patches over GraphQL. Client-side code can implement live data in a few lines by using any of the available RFC6902 "JSON Patch" libraries listed here: http://jsonpatch.com/
Why? Because I wanted to have the benefits of Live Data and it was unclear if the proposed @live
directive will ever be added to GraphQL.
This library came about as a result of the conversation at graphql/graphql-spec#386
Pull requests are very welcome.
npm install graphql-live-subscriptions
import {
liveSubscriptionTypeDef,
subscribeToLiveData,
} from 'graphql-live-subscriptions'
const schemaString = `
type Subscription
type Query {
jedis: [Jedi!]!
}
type House {
id: ID!
address(includePostalCode: Boolean!): String!
numberOfCats: Int!
numberOfDogs: Int!
}
type Jedi {
id: ID!
name: String!
houses: [House!]!
}
`
const resolvers = {
/* graphql-live-subscriptions requires a JSON Scalar resolver */
JSON: GraphQLJSON,
Subscription: {
live: {
resolve: source => source,
subscribe: subscribeToLiveData({
initialState: (source, args, context) => context.store.state,
eventEmitter: (source, args, context) => context.store.eventEmitter,
sourceRoots: {
Jedi: ['houses'],
},
}),
},
},
House: {
address: (house, args) => {
if (args.includePostalCode) {
return `${house.address} ${house.postalCode}`
}
return house.address
},
},
Jedi: {
houses: (jedi, args, context) => {
const { state } = context.store
return jedi.houseIDs.map(id => (
state.houses.find(house => house.id === id)
))
},
},
}
const schema = makeExecutableSchema({
typeDefs: [
schemaString,
liveSubscriptionTypeDef(),
],
resolvers,
})
subscription {
live {
query {
jedis {
firstName
lastName
houses {
address
}
}
}
patch { op, path, from, value }
}
}
typedefs for the live subscription.
arguments:
type = 'LiveSubscription'
- the type of the subscriptionqueryType = 'Query'
- the name of the query root that the live subscription will wrapsubscriptionName = 'live'
- the name of the live subscription
For use with programmatically constructed types. Returns a GraphQLDataType
with:
- a
query
field - immediately responds with the initial results to the live subscription like aquery
operation would. - a
patch
field - RFC6902 patch sets sent to the client to update the initialquery
data.
arguments:
initialState
function(source, args, context) returns the latest value to be passed to the query resolver.eventEmitter
function(source, args, context) returns either an EventEmitter or a Promise. Events:emit('update', { nextState })
- graphql-live-subscriptions will generate a patch for us by comparing the next state to the previous state and send it to the subscriber.emit('patch', { patch })
- graphql-live-subscriptions will send the patch provided directly to the subscriber.
sourceRoots
Object {[typeName: string]: [fieldName: string]} - a map of all fields which are not entirely based on their parent's source's state. By default the diffing algorithm only checks for changes to a field if it's parent's source has changed. If it is possible for a field to change it's value or the value of a field nested inside it without the source value changing then it needs to be listed here otherwise it will not generate patches when it changes.
returns an AsyncIterator that implements the sending of query's and patches.
graphql-live-subscriptions is MIT-licensed.