Python中使用MongoEngine

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

通常应用都是使用MVC框架来设计的，为了更好地维持MVC结构，须要把数据库操做部分做为model抽离出来，这就须要借助MongoEngine

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

MongoEngine提供的抽象是基于类的，建立的全部模型都是类

 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，至关于建立一个用来保存数据的数据结构，即数据已相似数据结构的形式存入数据库中，一般把这样的一些类都存放在一个脚本中，做为应用的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() #返回全部的文档对象列表
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)