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在Python中使用MongoEngine操作數(shù)據(jù)庫教程實(shí)例

更新時(shí)間：2019年12月03日 11:17:35 作者：慕塵

這篇文章主要介紹了在Python中使用MongoEngine操作數(shù)據(jù)庫教程實(shí)例,文中通過示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值,需要的朋友可以參考下

pymongo來操作MongoDB數(shù)據(jù)庫，但是直接把對(duì)于數(shù)據(jù)庫的操作代碼都寫在腳本中，這會(huì)讓應(yīng)用的代碼耦合性太強(qiáng)，而且不利于代碼的優(yōu)化管理

一般應(yīng)用都是使用MVC框架來設(shè)計(jì)的，為了更好地維持MVC結(jié)構(gòu)，需要把數(shù)據(jù)庫操作部分作為model抽離出來，這就需要借助MongoEngine

MongoEngine是一個(gè)對(duì)象文檔映射器（ODM），相當(dāng)于一個(gè)基于SQL的對(duì)象關(guān)系映射器（ORM）

MongoEngine提供的抽象是基于類的，創(chuàng)建的所有模型都是類

安裝

pip install mongoengine

使用時(shí)先聲明一個(gè)繼承自MongoEngine.Document的類

在類中聲明一些屬性，相當(dāng)于創(chuàng)建一個(gè)用來保存數(shù)據(jù)的數(shù)據(jù)結(jié)構(gòu)，即數(shù)據(jù)已類似數(shù)據(jù)結(jié)構(gòu)的形式存入數(shù)據(jù)庫中，通常把這樣的一些類都存放在一個(gè)腳本中，作為應(yīng)用的Model模塊

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() #返回所有的文檔對(duì)象列表
for u in users:
  print("name:",u.name,",age:",u.age)

保存文檔

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)

查詢10=<年齡<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)

查詢10=<年齡<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)

查詢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設(shè)為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)