Python中使用MongoEngine

2021-08-25 09:33:10

pymongo来操作MongoDB数据库，但是直接把对于数据库的操作代码都写在脚本中，这会让应用的代码耦合性太强，而且不利于代码的优化管理

一般应用都是使用MVC框架来设计的，为了更好地维持MVC结构，需要把数据库操作部分作为model抽离出来，这就需要借助MongoEngine

MongoEngine是一个对象文档映射器（ODM），相当于一个基于SQL的对象关系映射器（ORM）

MongoEngine提供的抽象是基于类的，创建的所有模型都是类

安装

pip install mongoengine

使用时先声明一个继承自MongoEngine.Document的类

在类中声明一些属性，相当于创建一个用来保存数据的数据结构，即数据已类似数据结构的形式存入数据库中，通常把这样的一些类都存放在一个脚本中，作为应用的Model模块

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

users = Users.objects.all() #返回所有的文档对象列表

for u in users:

    print("name:",u.name,",age:",u.age)

保存文档

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

user1 = Users(

    name='zz',

    age= 11

)

user1.save()

print(user1.name)

user1.name = 'zz11'

user1.save()

print(user1.name)

查询10=<年龄<30的，按姓名排列

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

user_search = Users.objects(age__gte=10, age__lt=33).order_by('name')

for u in user_search:

    print("name:",u.name,",age:",u.age)

查询10=<年龄<30的，按姓名倒序

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

user_search = Users.objects(age__gte=10, age__lt=33).order_by('-name')

for u in user_search:

    print("name:",u.name,",age:",u.age)

查询name=zz11

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

tmp = Users.objects(name="zz11")

for u in tmp:

    print("name:",u.name,",age:",u.age)

修改name=zz11的age加1

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

tmp = Users.objects(name="zz11").update(inc__age=1)

tmp = Users.objects(name="zz11")

for u in tmp:

    print("name:",u.name,",age:",u.age)

修改name=zz11的age设为55

from mongoengine import *

connect('test', host='localhost', port=27017)

import datetime

class Users(Document):

    name = StringField(required=True, max_length=200)

    age = IntField(required=True)

tmp = Users.objects(name="zz11").update(set__age=55)

tmp = Users.objects(name="zz11")

for u in tmp:

    print("name:",u.name,",age:",u.age)

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