TCB series learning articles - using redis extension in cloud functions

When should I use it Redis？

Redis The applicable scenarios include but are not limited to ：

• Counter ： because Redis The operation is atomic , Count the data of high concurrent users by atomic increment or decrement , Like the number of likes 、 Number of collections 、 Number of shares 、 The amount of stock in a rush purchase 、 Total number of articles 、 Number of comments, etc. ;
• Ranking List ：Redis Data structures that support sets and ordered sets , And it runs in memory , So you can store some data similar to leaderboard , Like recently 、 Hottest 、 The highest click through rate 、 The most active 、 Articles with the most comments and so on 、 goods 、 The user etc. ;
• Hashtable ： User fan list 、 User likes list 、 User collection list 、 User follow list, etc ;
• Automatic sorting ： Storage time stamp , Over time , Automatically sort according to the latest dynamic list of users ;
• Session cache ： Use Redis Do session caching , take web session Store in Redis in ;
• Full page caching FPC： The server-side rendering results can be cached in Redis in ;
• Record user operation information ： Whether the user likes it or not 、 Is the user favorite 、 Whether users share, etc .

install Redis expand

1、 Install the extension

Open Tencent cloud console , Go to the environment details page , Click on the left 「 Expansion management 」, Go to the expansion management details page , And click the Redis expand , Installation expansion .

2、 establish Redis example

If there are no instances in the installation （ I haven't bought yet Redis database , Click new instance ）, If there are already instances, you can skip , Go to the next step .

Buy Redis database , Create examples , Set up a private network .

After creating the instance, go back to the extension and select just created （ Or what we have ） Example ：

Click Finish to create ：

The installation is successful when you see the following extensions ：

3、 obtain Redis Information

After the creation, view the development related information （ Here we can see the cloud functions created together ）：

Use... In cloud functions Redis

In the cloud function, you can use Redis Client connections and operations Redis example , Recommended redis (opens new window).

1、 Installation dependency

First go to Redis In the cloud function directory of , And then execute the command npm init -y Initialize a configuration file .

And then , perform npm install --save redis To install the corresponding dependencies .

After installation , Cloud function directory will appear package.json file , The content is similar to the following ：

{
  "name": "redis",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "redis": "^3.0.2"
  }
}

2、 call Redis

Next, you can call it in code Redis Database .

Because of the use of cloud development Redis expand , The corresponding configuration will be brought automatically in the system running environment , You can directly use the corresponding environment variables to link Redis database .

'use strict';

const redis = require('redis')

let client = redis.createClient({
  host: process.env.HOST,
  port: process.env.PORT,
  //  You need to fill in a real password 
  password: 'xxx'
})

exports.main = async (event, context, callback) => {
  let res = await new Promise((resolve, reject) => {
    client.get('test', function (err, reply) {
      if (err) {
        resolve({
          err
        })
      }
      resolve({
        data: reply.toString()
      }）
    })
  })
  return { res }
}