Detailed explanation of application cases of redis in nodejs-JS Tutorial-php.cn

This time I will bring you a detailed explanation of the application cases of redis in nodejs. What are theprecautionsfor the application of redis in nodejs. The following is a practical case, let's take a look.

redis is an in-memory database with very good performance. It is deployed as acaching datalibrary between the application and mysql data, which can greatly improve the performance of the application. Here is a brief introduction to the nodejs client The demo program for terminal operation of redis

redis can store a total of 5data types, which arestring, list, set, three columns, and ordered set; Here, the additions, deletions, checks and modifications of these five data types will be processed one by one;

1. Installation of redis on mac:

https://redis. io/download, the current stable version I am using is 4.0.9. After decompressing, enter the redis-4.0.9 directory, execute make && sudo make install, and wait a few minutes to install it;

2 , redis startup:

Execute redis-server on the command line to start, the default port is 6379;

3. Install nodejs client:

Create the redis-node directory, After yarn init -y in this directory, execute the command: yarn add redis to install the redis client of nodejs. Reference document: https://github.com/NodeRedis/node_redis

4. In redis- In the node directory, execute node on the terminal, and you can execute the nodejs code responsively on the terminal for testing. Let’s start the demo program

First, create a client and connect to the redis server. After executing the following connection Before client code, please make sure that the redis server is running: the terminal provider can execute redis-server, the default port is 6379;

const redis = require('redis'); const client = redis.createClient(); //默认连接localhost:6379，具体配置参数可以参考文档https://github.com/NodeRedis/node_redis

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If everything goes well, we have created a client to connect to the redis server. Subsequent operations are performed on the client object.

1. String type

Although it is a string type, the data that can be stored includes strings, integers and floating point numbers.

var res = client.set('name', 'abczhijia', (err, data) => { console.log('err: ', err, ' data: ', data); }); // err: null data: OK，res的值是true client.get('name', (err, data) => { console.log('err: ', err, ' data: ', data); }); // err: null data: abczhijia

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For the sake of simplicity, we define acallback functionfor outputting data:

const cb = (err, data) => { console.log('err: ', err, ' data: ', data, ' data type: ', typeof data); }

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Let’s do a test for integers:

client.set('age', 20, cb); //err: null data: OK data type: string client.get('age', cb); //err: null data: 20 data type: string

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It can be seen that although the setting is an integer, when it is output, it is still a string, so if you want to perform calculations, you need to do the conversion yourself in the callback function

2. List data type

//从右侧推入 client.rpush('friends', 'mike', 'jhon', cb); //err: null data: 2 data type: number client.lrange('friends', 0, -1, cb); //err: null data: [ 'mike', 'jhon' ] data type: object //从左侧推入 client.lpush('friends', 'sam', 'bob', cb); //err: null data: 4 data type: number client.lrange('friends', 0, -1, cb); // err: null data: [ 'bob', 'sam', 'mike', 'jhon' ] data type: object //从右侧弹出 client.rpop('friends', cb); //err: null data: jhon data type: string //从左侧弹出 client.lpop('friends', cb); //err: null data: bob data type: string //打印看看发生了啥 client.lrange('friends', 0, -1, cb); // err: null data: [ 'sam', 'mike' ] data type: object //查看索引位置的值 client.lindex('friends', 0, cb); // err: null data: sam data type: string //对列表进行裁剪 client.rpush('friends', 'tom', 'bryant', cb)// err: null data: 4 data type: number client.ltrim('friends', 1, 2, cb); //err: null data: OK data type: string client.lrange('friends', 0, -1, cb); //err: null data: [ 'mike', 'tom' ] data type: object

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Note here that the list operation can push one or more data from the right rpush, or push one or more data from the left lpush; in addition, when taking the value, you need to specify the start and end Position, if you want to get the entire position, you can write the end position as -1.

3. Collection data type

//往集合ids中加几个元素 client.sadd('ids', 1, 2, cb); //err: null data: 2 data type: number //查看集合元素 client.smembers('ids', cb); //err: null data: [ '1', '2' ] data type: object //从集合中删除元素 client.srem('ids', 2, cb); // err: null data: 1 data type: number //看看发生了啥 client.smembers('ids', cb); //err: null data: [ '1' ] data type: object //看看集合有多少个元素 client.scard('ids', cb); //err: null data: 1 data type: number //再加几个元素进去 client.sadd('ids', 3, 5, 8, 9); // //判断元素是否在集合内 client.sismember('ids', 8, cb); // err: null data: 1 data type: number client.sismember('ids', 80, cb); //err: null data: 0 data type: number

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4. Hash data type

//往散列上添加多组键值对 client.hmset('phone', 'price', 5888, 'name', 'iphonex', cb); //err: null data: OK data type: string //查看多个键的值 client.hmget('phone', 'price', 'name', cb); //err: null data: [ '5888', 'iphonex' ] data type: object //查看键值对的数量 client.hlen('phone', cb); //err: null data: 2 data type: number //删掉其中一个键值对 client.hdel('phone', 'price', cb); //err: null data: 1 data type: number //看看price是否还在？ client.hmget('phone', 'price', cb); //err: null data: [ null ] data type: object,原来只留下了null //再加几个属性 client.hmset('phone', 'vendor', 'apple', 'madein', 'china', cb); //取出所有的键值对 client.hgetall('phone', cb); //err: null data: { name: 'iphonex', vendor: 'apple', madein: 'china' } data type: object //取出所有的键 client.hkeys('phone', cb); //err: null data: [ 'name', 'vendor', 'madein' ] data type: object //取出所有的值 client.hvals('phone', cb); //err: null data: [ 'iphonex', 'apple', 'china' ] data type: object //判断键是否存在 client.hexists('phone', 'name', cb); //err: null data: 1 data type: number client.hexists('phone', 'price', cb); //err: null data: 0 data type: number

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I believe you have read the case in this article After mastering the method, please pay attention to other related articles on the php Chinese website for more exciting content!