Python中使用MongoEngine2，,mongoengin

Python中使用MongoEngine2，,mongoengin

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, username=‘test‘, password=‘test‘)# Defining our documents# 定义文档user,post,对应集合user,postclass 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 databaseclass 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 savedclass Page(DynamicDocument):    title = StringField(max_length=200, required=True)    date_modified = DateTimeField(default=datetime.now())

添加数据

john = User(email=‘john@example.com‘, first_name=‘John‘, last_name=‘Tao‘).save()ross = User(email=‘ross@example.com‘)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 tagspage = 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().authorprint 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# 多条件查询(导入Q类) User.objects((Q(country=‘uk‘) & Q(age__gte=18)) | Q(age__gte=20))   # 更新文档ross = User.objects(first_name = ‘Ross‘)ross.update(date = datetime.now())User.objects(first_name=‘John‘).update(set__email=‘123456@qq.com‘)//对 lorem 添加商品图片信息lorempic = GoodsPic(name=‘l2.jpg‘, path=‘/static/images/l2.jpg‘)lorem = Goods.objects(id=‘575d38e336dc6a55d048f35f‘)lorem.update_one(push__pic=lorempic)# 删除文档ross.delete()

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。

Python中使用MongoEngine2