hasura graphql subscriptions 使用

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subscriptions graphql 的一项实时数据推送的功能，还是很方便的，自己在直接使用subscriptions-transport-ws npm 包
的时候运行一直有错误(主要是依赖的apollo版本)，还好hasura graphql 默认提供了一个开发模版，还是比较方便的

模版clone

git clone https://github.com/hasura/nodejs-graphql-subscriptions-boilerplate.git

基本代码集成

使用模版（graphql server是自己的）

const { execute } = require('apollo-link'); const { WebSocketLink } = require('apollo-link-ws'); const { SubscriptionClient } = require('subscriptions-transport-ws'); const ws = require('ws'); const getWsClient = function(wsurl) { const client = new SubscriptionClient( wsurl, {reconnect: true}, ws ); return client; };// wsurl: GraphQL endpoint // query: GraphQL query (use gql`` from the 'graphql-tag' library) // variables: Query variables object const createSubscriptionObservable = (wsurl, query, variables) => { const link = new WebSocketLink(getWsClient(wsurl)); return execute(link, {query: query, variables: variables}); }; const gql = require('graphql-tag'); const SUBSCRIBE_QUERY = gql` subscription { apps { dr id appname } } `; function main() { const subscriptionClient = createSubscriptionObservable( 'http://myserver:port/v1alpha1/graphql', // GraphQL endpoint SUBSCRIBE_QUERY, // Subscription query ); var consumer = subscriptionClient.subscribe(eventData => { console.log("Received event: "); console.log(JSON.stringify(eventData, null, 2)); }, (err) => { console.log('Err'); console.log(err); }); } main();

效果

说明

主要是package.json

package.json

{ "name": "nodejs-graphql-subscriptions-boilerplate", "version": "1.0.0", "description": "", "main": "src/index.js", "scripts": { "start":"node index" }, "author": "Karthik V", "license": "ISC", "dependencies": { "apollo-link": "^1.2.2", "apollo-link-ws": "^1.0.8", "graphql": "^0.13.2", "graphql-tag": "^2.9.2", "subscriptions-transport-ws": "^0.9.12", "ws": "^5.2.2" // 这个比较重要，一般可能会忘记添加，会有提示websocket 没有实现，还好官方模版提供好了 } }

数据查询demo

subscription: subscription appdemo($input:Int!) { apps (where:{ id: { _eq:$input }} ) { dr id appname } } 查询参数： const subscriptionClient = createSubscriptionObservable( 'http://server:port/v1alpha1/graphql', // GraphQL endpoint SUBSCRIBE_QUERY, // Subscription query {id:1} );