4.Python操作Redis：哈希(H

发布时间：2019-09-24 08:18:55编辑：auto阅读（1899）

Redis 数据库hash数据类型是一个string类型的key和value的映射表，适用于存储对象。Redis 中每个 hash 可以存储 232 - 1 键值对（40多亿）。
Python的redis模块实现了Redis哈希（Hash）命令行操作的几乎全部命令，包括HDEL、HEXISTS、HGET、HGETALL、HINCRBY、HKEYS、HLEN 、HMGET 、HMSET 、HSET 、HSETNX 、HVALS 。但是无法支持HINCRBYFLOAT 、HSCAN 等命令。

函数说明

1. HDEL: 删除对应哈希（Hash）表的指定键（key）的字段，hdel(self, name, key)
2. HEXISTS: 检测哈希（Hash）表对应键（key）字段是否存在，返回布尔逻辑，hexists(self, name, key)
3. HGET: 获取哈希（Hash）指定键（key）对应的值，hget(self, name, key)
4. HGETALL: 获取哈希(Hash)表的键-值对（key-value pairs）,返回python字典类型数据，hgetall(self, name)
5. HINCRBY: 为哈希表（Hash）指定键（key）对应的值（key）加上指定的整数数值（int，可为负值），参见 [Python操作Redis：字符串(String)]，(http://blog.csdn.net/u012894975/article/details/51285733)hincrby(self, name, key, amount=1)，Redis 中本操作的值被限制在 64 位(bit)有符号数字。
6. HKEYS: 返回哈希表（Hash）对应键（key）的数组（Python称之为列表List），hkeys(self, name)
7. HLEN: 获取哈希表（Hash）中键-值对（key-value pairs）个数，hlen(self, name)
8. HMGET: 获取哈希表（Hash）中一个或多个给点字段的值，不存在返回nil(Redis命令行)/None(Python)，hmget(self, name, keys)，其中keys可以为列表（list）
9. HMSET: 设置对个键-值对（key-value pairs）到哈希表（Hash）中，python输入值（mapping）为字典（dictionary）类型，hmset(self, name, mapping)
10. HSET: 为哈希表（Hash）赋值，若键（key）存在值（value）则覆盖，不存在则创建，hset(self, name, key, value)
11. HSETNX：为哈希表（Hash）不存值（value）的键（key）赋值，存在操作无效，对应值（value）无变化，hsetnx(self, name, key, value)
12. HVALS：返回哈希表（Hash）对应值（value）的列表，hvals(self, name)

代码示例

#!/usr/bin/python
import redis
import time
## Connect local redis service
client =redis.Redis(host='127.0.0.1',port=6379,db=0)
print "Connection to server successfully!"
dicKeys = client.keys("*")
print dicKeys

### Redis hash command part Start ###
# hset: Set key to value with hash name,hset(self, name, key, value)
# hget: Return the value of ``key`` within the hash ``name``, hget(self, name, key)
client.hset('myhash','field1',"foo")
hashVal = client.hget('myhash','field1')
print "Get hash value:",hashVal

# Get none-value
hashVal = client.hget('myhash','field2')
print "None hash value:",hashVal

# hexists: Returns a boolean indicating if ``key`` exists within hash ``name``
keyList= ['field1','field2']
for key in keyList:
    hexists = client.hexists('myhash',key)
    if hexists :
        print "Exist in redis-hash key:",key
    else:
        print "Not exist in redis-hash key:",key

# hgetall: Return a Python dict of the hash's name/value pairs
client.hset('myhash','field2',"bar")
valDict = client.hgetall('myhash')
print "Get python-dict from redis-hash",valDict

# hincrby: Increment the value of ``key`` in hash ``name`` by ``amount``
# default increment is 1,
client.hset('myhash','field',20)
client.hincrby('myhash','field')
print "Get incrby value(Default):",client.hget('myhash','field')
client.hincrby('myhash','field',2)
print "Get incrby value(step: 2):",client.hget('myhash','field')
client.hincrby('myhash','field',-3)
print "Get incrby value(step: -3):",client.hget('myhash','field')

# no method hincrbyfloat

#hkeys: Return the list of keys within hash ``name``
kL = client.hkeys('myhash')
print "Get redis-hash key list",kL

#hlen: Return the number of elements in hash ``name``
lenHash =client.hlen('myhash')
print "All hash length:",lenHash

#hmget: Returns a list of values ordered identically to ``keys``
#hmget(self, name, keys), keys should be python list data structure
val =client.hmget('myhash',['field','field1','field2','field3','fieldx'])
print "Get all redis-hash value list:",val

#hmset:  Sets each key in the ``mapping`` dict to its corresponding value in the hash ``name``
hmDict={'field':'foo','field1':'bar'}
hmKeys=hmDict.keys()
client.hmset('hash',hmDict)
val = client.hmget('hash',hmKeys)
print "Get hmset value:",val

#hdel: Delete ``key`` from hash ``name``
client.hdel('hash','field')
print "Get delete result:",client.hget('hash','field')

#hvals:  Return the list of values within hash ``name``
val = client.hvals('myhash')
print "Get redis-hash values with HVALS",val

#hsetnx: Set ``key`` to ``value`` within hash ``name`` if ``key`` does not exist.
#      Returns 1 if HSETNX created a field, otherwise 0.
r=client.hsetnx('myhash','field',2)
print "Check hsetnx execute result:",r," Value:",client.hget('myhash','field')
r=client.hsetnx('myhash','field10',20)
print "Check hsetnx execute result:",r,"Value",client.hget('myhash','field10')

hashVal = client.hgetall('profile')
print hashVal
#Empty db
client.flushdb()

参考资料：
1、Redis 哈希(Hash)
2、Python redis文档（python交互模式下命令>>>help redis）

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