实例存储之shelve

Posted 2022-08-08 wx62b90c63c9df5

对于传统的数据库，大家都很清楚是拿来存储数字，字符串，json等等， 但是有一点这一类的数据是静态的。如果想保存动态数据，比如对象的实例，有没有可能呢。答案是肯定的。

shelve模块就提供了这种可能性，它是基于pickle模块，是数据持久化的解决方案。

installation

shelve是python内置模块，无需额外安装。

保存实例到文件

import shelve

db_name = test.db

class Session(object):
    def __init__(self, user, password):
        self.user = user
        self.password = password

    def run(self, command):
        print(executing command: .format(command))


class Host(object):
    def __init__(self, user, password, times):
        self.user = user
        self.password = password
        self.times = times

        self.child = Session(user, password)

    def perform(self):
        print(user: .format(self.user))
        print(password: .format(self.password))

        for i in range(1, self.times+1):
            self.child.run(hello command .format(i))

s = shelve.open(db_name)
s[host] = Host(rock, 123456, 10)
s.close()

从文件中读取实例

import shelve

from shelve_test01 import Session, Host

db_name = test.db
s = shelve.open(db_name)

host = s[host]
host.perform()
print(host.child.user)

user: rock
password: 123456
executing command: hello command 1
executing command: hello command 2
executing command: hello command 3
executing command: hello command 4
executing command: hello command 5
executing command: hello command 6
executing command: hello command 7
executing command: hello command 8
executing command: hello command 9
executing command: hello command 10
rock

是不是觉得很惊艳，看看自己的项目，有没有觉得如果用上shelve，可以做很多创新？