python mongoengine

安装MongoEngine

pip install mongoengine

mongoengine基本用法实例：

from mongoengine import *
from datetime import datetime

#连接数据库:test
# connect('test') # 连接本地test数据库
connect('test', host='127.0.0.1', port=27017)

# Defining our documents
# 定义文档user,post,对应集合user,post
class User(Document): # required为True则必须赋予初始值 email = StringField(required=True) first_name = StringField(max_length=50) last_name = StringField(max_length=50) date = DateTimeField(default=datetime.now(), required=True) # Embedded documents,it doesn’t have its own collection in the database class Comment(EmbeddedDocument): content = StringField() name = StringField(max_length=120) class Post(Document): title = StringField(max_length=120, required=True) # ReferenceField相当于foreign key author = ReferenceField(User) tags = ListField(StringField(max_length=30)) comments = ListField(EmbeddedDocumentField(Comment)) # 允许继承 meta = {'allow_inheritance': True} class TextPost(Post): content = StringField() class ImagePost(Post): image_path = StringField() class LinkPost(Post): link_url = StringField() # Dynamic document schemas:DynamicDocument documents work in the same way as Document but any data / attributes set to them will also be saved class Page(DynamicDocument): title = StringField(max_length=200, required=True) date_modified = DateTimeField(default=datetime.now())

添加数据

john = User(email='[email protected]', first_name='John', last_name='Tao').save()
ross = User(email='[email protected]')
ross.first_name = 'Ross'
ross.last_name = 'Lawley'
ross.save()

comment1 = Comment(content='Good work!',name = 'LindenTao')
comment2 = Comment(content='Nice article!')
post0 = Post(title = 'post0',tags = ['post_0_tag'])
post0.comments = [comment1,comment2]
post0.save()

post1 = TextPost(title='Fun with MongoEngine', author=john)
post1.content = 'Took a look at MongoEngine today, looks pretty cool.'
post1.tags = ['mongodb', 'mongoengine']
post1.save()

post2 = LinkPost(title='MongoEngine Documentation', author=ross)
post2.link_url = 'http://docs.mongoengine.com/'
post2.tags = ['mongoengine']
post2.save()

# Create a new page and add tags
page = Page(title='Using MongoEngine')
page.tags = ['mongodb', 'mongoengine']
page.save()

创建了三个集合:user,post,page

查看数据

# 查看数据
for post in Post.objects:
    print post.title
    print '=' * len(post.title)

    if isinstance(post, TextPost):
        print post.content

    if isinstance(post, LinkPost):
        print 'Link:', post.link_url

# 通过引用字段直接获取引用文档对象 
for post in TextPost.objects:
    print post.content
    print post.author.email  
au = TextPost.objects.all().first().author
print au.email

# 通过标签查询 
for post in Post.objects(tags='mongodb'):
    print post.title

num_posts = Post.objects(tags='mongodb').count()
print 'Found %d posts with tag "mongodb"' % num_posts

# 更新文档
ross = User.objects(first_name = 'Ross')
ross.update(date = datetime.now())
User.objects(first_name='John').update(set__email='[email protected]')

备注

ORM全称“Object Relational Mapping”，即对象-关系映射，就是把关系数据库的一行映射为一个对象，也就是一个类对应一个表，这样，写代码更简单，不用直接操作SQL语句。

链接：

http://docs.mongoengine.org/index.html#
https://pypi.python.org/pypi/mongoengine/