Python Redis data processing methods

1. Preface

Redis: Remote Dictionary Server, that is: remote dictionary service. The bottom layer of Redis is written in C language. It is an open source, memory-based NoSql database

Because of Redis The performance far exceeds that of other databases, and it supports advantages such as clustering, distribution, and master-slave synchronization, so it is often used in scenarios such as caching data, high-speed reading and writing

2. Preparation

We will use the cloud Server Centos 7.8 Installing Redis-Server as an example

First, install the Redis database on the cloud server

# 下载epel仓库
yum install epel-release

# 安装redis
yum install redis

Then, modify the Redis configuration file through the vim command, open the remote connection, and set the connection password

Configuration file directory:/etc/redis.conf

• bind is changed to 0.0.0.0, allowing external network access

• ##requirepass Set an access password

# vim /etc/redis.conf
# 1、bing从127.0.0.1修改为:0.0.0.0，开放远程连接
bind 0.0.0.0 

# 2、设置密码
requirepass 123456

It should be pointed out that in order to ensure the security of cloud server data, when Redis opens remote access, the password must be strengthened

Then, start Redis Service, open the firewall and port, configure the cloud server security group

By default, the port number used by the Redis service is 6379

In addition, it needs to be configured in the cloud server security group to ensure that the Redis database Can connect normally

# 启动Redis服务，默认redis端口号是6379
systemctl start redis 

# 打开防火墙
systemctl start firewalld.service

# 开放6379端口
firewall-cmd --zone=public --add-port=6379/tcp --permanent   

# 配置立即生效
firewall-cmd --reload

After completing the above operations, we can connect through Redis-CLI or Redis client tool

Finally, to use Python to operate Redis, we need to use pip to install a dependency

# 安装依赖，便于操作redis
pip3 install redis

3. Practical combat

Before operating the data in Redis, we need to use the Host, port number, and password to instantiate a Redis connection object

from redis import Redis

class RedisF(object):

    def __init__(self):
        # 实例化Redis对象
        # decode_responses=True，如果不加则写入的为字节类型
        # host：远程连接地址
        # port：Redis端口号
        # password：Redis授权密码
        self.redis_obj = Redis(host='139.199.**.**',port=6379,password='123456',decode_responses=True,charset='UTF-8', encoding='UTF-8')

Next we use Taking the operation of strings, lists, set collections, zset collections, hash tables, and transactions as examples, let's talk about the methods of operating these data in Python

1. String operations

There are two ways to operate strings This way, the operation methods are: set() and mset()

Among them: set() can only save one value at a time, the parameter meaning is as follows

• name: key, represents the key

• value: value, the value to be saved

• ex: expiration time, in seconds, if not set, then it will never expire; otherwise, it will be deleted if it expires

• px: expiration time, in milliseconds

• nx/xx: whether the set operation is The execution is related to whether the name key exists.

The operation methods for obtaining the value and deleting the value are: get(Key), delete(Key or Keys)

# set()：单字符串操作
# 添加一个值，并设置超时时间为120s
 self.redis_obj.set('name', 'airpython', ex=120)

# get()：获取这个值
print(self.redis_obj.get('name'))

# delete()：删除一个值或多个值
self.redis_obj.delete('name')
print(self.redis_obj.get('name'))

For the setting of multi-valued data, you only need to call the mset() method and use the key-value pairs to form a dictionary as a parameter for the data to be inserted.

Similarly, Redis provides The mget() method can obtain the values ​​​​of multiple keys at one time

# mset()：设置多个值
self.redis_obj.mset({"foo": "foo1", "zoo": "zoo1"})

# mget()：获取多个值
result = self.redis_obj.mget("foo", "zoo")
print(result)

2. List operations

Redis provides many methods for operating lists, among which the more common ones are as follows:

• lpush/rpush: Insert one or more values ​​into the head or tail of the list, where lpush represents the head insertion; rpush represents the tail insertion of data

• lset: Insert the value into the corresponding position in the list through the index

• linsert: Insert data before or after the list element

##lindex : Get an element in the list through index, where 0 represents the first element; -1 represents the last element
#lrange: By specifying the starting position and ending position, from Get the value of the specified area in the list
llen: Get the length of the list. If the list corresponding to the Key does not exist, return 0
lpop: Remove and return the first element in the list
rpop: Remove and return the last element in the list
The example code is as follows ：

def manage_list(self):
    """
    操作列表
    :return:
    """
    # 1、新增一个列表，并左边插入一个数据
    # 注意：可以一次加入多个元素，也可以一个个元素的加入
    self.redis_obj.lpush('company', '阿里', '腾讯', '百度')

    # 2、移除第一个元素
    self.redis_obj.lpop("company")

    # 3、右边插入数据
    self.redis_obj.rpush('company', '字节跳动', '小米')

    # 4、移除最后一个元素
    self.redis_obj.rpop("company")

    # 5、获取列表的长度
    self.redis_obj.llen("company")

    # 6、通过索引，获取列表中的某一个元素（第二个元素）
    print('列表中第二个元素是：', self.redis_obj.lindex("company", 1))

    # 7、根据范围，查看列表中所有的值
    print(self.redis_obj.lrange('company', 0, -1))

3. Operating Set collection

Set is an unordered collection of elements. The elements in the collection cannot be repeated. Redis also provides many methods to facilitate the operation of Set collection

Among them, the more commonly used methods are as follows:

sadd: Add elements to the collection. Elements that already exist in the collection will be ignored. If the collection does not exist, create a new collection
scard: Returns the number of elements in the collection
smembers: Returns all elements in the collection

• ##srem : Remove one or more elements from the set, ignore if the element does not exist

• sinter: Return the intersection of two sets, the result is still a set

• sunion: Returns the union of two sets

• sdiff: Using the first set parameter as the standard, returns the difference of the two sets

• sunionstore: Calculate the union of two sets and save it to a new set

• sismember: Determine whether an element exists in the set

• spop: Randomly delete an element in the set and return

• The specific example code is as follows:

def manage_set(self):
    """
    操作set集合
    :return:
    """
    self.redis_obj.delete("fruit")

    # 1、sadd：新增元素到集合中
    # 添加一个元素：香蕉
    self.redis_obj.sadd('fruit', '香蕉')

    # 再添加两个元素
    self.redis_obj.sadd('fruit', '苹果', '桔子')

    # 2、集合元素的数量
    print('集合元素数量：', self.redis_obj.scard('fruit'))

    # 3、移除一个元素
    self.redis_obj.srem("fruit", "桔子")

    # 再定义一个集合
    self.redis_obj.sadd("fruit_other", "香蕉", "葡萄", "柚子")

    # 4、获取两个集合的交集
    result = self.redis_obj.sinter("fruit", "fruit_other")
    print(type(result))
    print('交集为：', result)

    # 5、获取两个集合的并集
    result = self.redis_obj.sunion("fruit", "fruit_other")
    print(type(result))
    print('并集为：', result)

    # 6、差集，以第一个集合为标准
    result = self.redis_obj.sdiff("fruit", "fruit_other")
    print(type(result))
    print('差集为：', result)

    # 7、合并保存到新的集合中
    self.redis_obj.sunionstore("fruit_new", "fruit", "fruit_other")
    print('新的集合为：', self.redis_obj.smembers('fruit_new'))

    # 8、判断元素是否存在集合中
    result = self.redis_obj.sismember("fruit", "苹果")
    print('苹果是否存在于集合中', result)

    # 9、随机从集合中删除一个元素，然后返回
    result = self.redis_obj.spop("fruit")
    print('删除的元素是:', result)

    # 3、集合中所有元素
    result = self.redis_obj.smembers('fruit')

    print("最后fruit集合包含的元素是:", result)

4. Operation zset collection

Zset collections are ordered compared to ordinary set collections. The elements in the zset collection include: values ​​and scores, where scores are used for sorting

其中，比较常用的方法如下：

• zadd：往集合中新增元素，如果集合不存在，则新建一个集合，然后再插入数据

• zrange：通过起始点和结束点，返回集合中的元素值（不包含分数）;如果设置withscores=True，则返回结果会带上分数

• zscore：获取某一个元素对应的分数

• zcard：获取集合中元素个数

• zrank：获取元素在集合中的索引

• zrem：删除集合中的元素

• zcount：通过最小值和最大值，判断分数在这个范围内的元素个数

实践代码如下：

def manage_zset(self):
    """
    操作zset集合
    :return:
    """
    self.redis_obj.delete("fruit")

    # 往集合中新增元素：zadd()
    # 三个元素分别是："banana", 1/"apple", 2/"pear", 3
    self.redis_obj.zadd("fruit", "banana", 1, "apple", 2, "pear", 3)

    # 查看集合中所有元素（不带分数）
    result = self.redis_obj.zrange("fruit", 0, -1)
    # ['banana', 'apple', 'pear']
    print('集合中的元素（不带分数）有：', result)

    # 查看集合中所有元素（带分数）
    result = self.redis_obj.zrange("fruit", 0, -1, withscores=True)
    # [('banana', 1.0), ('apple', 2.0), ('pear', 3.0)]
    print('集合中的元素（带分数）有：', result)

    # 获取集合中某一个元素的分数
    result = self.redis_obj.zscore("fruit", "apple")
    print("apple对应的分数为：", result)

    # 通过最小值和最大值，判断分数在这个范围内的元素个数
    result = self.redis_obj.zcount("fruit", 1, 2)
    print("集合中分数大于1，小于2的元素个数有：", result)

    # 获取集合中元素个数
    count = self.redis_obj.zcard("fruit")
    print('集合元素格式:', count)

    # 获取元素的值获取索引号
    index = self.redis_obj.zrank("fruit", "apple")
    print('apple元素的索引为：', index)

    # 删除集合中的元素：zrem
    self.redis_obj.zrem("fruit", "apple")
    print('删除apple元素后，剩余元素为：', self.redis_obj.zrange("fruit", 0, -1))

4、操作哈希

哈希表中包含很多键值对，并且每一个键都是唯一的

Redis 操作哈希表，下面这些方法比较常用：

• hset：往哈希表中添加一个键值对值

• hmset：往哈希表中添加多个键值对值

• hget：获取哈希表中单个键的值

• hmget：获取哈希表中多个键的值列表

• hgetall：获取哈希表中种所有的键值对

• hkeys：获取哈希表中所有的键列表

• hvals：获取哈表表中所有的值列表

• hexists：判断哈希表中，某个键是否存在

• hdel：删除哈希表中某一个键值对

• hlen：返回哈希表中键值对个数

对应的操作代码如下：

def manage_hash(self):
    """
    操作哈希表
    哈希：一个键对应一个值，并且键不容许重复
    :return:
    """
    self.redis_obj.delete("website")

    # 1、新建一个key为website的哈希表
    # 往里面加入数据：baidu（field），www.baidu.com(value)
    self.redis_obj.hset('website', 'baidu', 'www.alibababaidu.com')
    self.redis_obj.hset('website', 'google', 'www.google.com')

    # 2、往哈希表中添加多个键值对
    self.redis_obj.hmset("website", {"tencent": "www.qq.com", "alibaba": "www.taobao.com"})

    # 3、获取某一个键的值
    result = self.redis_obj.hget("website", 'baidu')
    print("键为baidu的值为：", result)

    # 4、获取多个键的值
    result = self.redis_obj.hmget("website", "baidu", "alibaba")
    print("多个键的值为:", result)

    # 5、查看hash表中的所有值
    result = self.redis_obj.hgetall('website')
    print("哈希表中所有的键值对为：", result)

    # 6、哈希表中所有键列表
    # ['baidu', 'google', 'tencent', 'alibaba']
    result = self.redis_obj.hkeys("website")
    print("哈希表，所有的键（列表）为:", result)

    # 7、哈希表中所有的值列表
    # ['www.alibababaidu.com', 'www.google.com', 'www.qq.com', 'www.taobao.com']
    result = self.redis_obj.hvals("website")
    print("哈希表，所有的值（列表）为:", result)

    # 8、判断某一个键是否存在
    result = self.redis_obj.hexists("website", "alibaba")
    print('alibaba这个键是否存在:', result)

    # 9、删除某一个键值对
    self.redis_obj.hdel("website", 'baidu')
    print('删除baidu键值对后，哈希表的数据包含：', self.redis_obj.hgetall('website'))

    # 10、哈希表中键值对个数
    count = self.redis_obj.hlen("website")
    print('哈希表键值对一共有：', count)

5、操作事务管道

Redis 支持事务管道操作，能够将几个操作统一提交执行

操作步骤是：

• 首先，定义一个事务管道

• 然后通过事务对象去执行一系列操作

• 提交事务操作，结束事务操作

下面通过一个简单的例子来说明：

def manage_steps(self):
    """
    执行事务操作
    :return:
    """
    # 1、定义一个事务管道
    self.pip = self.redis_obj.pipeline()

    # 定义一系列操作
    self.pip.set('age', 18)

    # 增加一岁
    self.pip.incr('age')

    # 减少一岁
    self.pip.decr('age')

    # 执行上面定义3个步骤的事务操作
    self.pip.execute()

    # 判断
    print('通过上面一些列操作，年龄变成:', self.redis_obj.get('age'))

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