在Python中使用mongoengine操作MongoDB教程

easy_install pymongo # 依赖库
easy_install mongoengine

from mongoengine import *
from datetime import datetime
# 连接数据库
connect('blog') # 连接本地blog数据库
# 如需验证和指定主机名
# connect('blog', host='192.168.3.1', username='root', password='1234')

# 定义分类文档
class Categories(Document):
 ' 继承Document类,为普通文档 '
 name = StringField(max_length=30, required=True)
 artnum = IntField(default=0, required=True)
 date = DateTimeField(default=datetime.now(), required=True)

cate = Categories(name="Linux") # 如果required为True则必须赋予初始值,如果有default,赋予初始值则使用默认值
cate.save() # 保存到数据库

# 返回集合里的所有文档对象的列表
cate = Categories.objects.all()

# 返回所有符合查询条件的结果的文档对象列表
cate = Categories.objects(name="Python")
# 更新查询到的文档:
cate.name = "LinuxZen"
cate.update()

class Posts(Document):
 artid = IntField(required=True)
 title = StringField(max_length=100, required=True)
 content = StringField(required=True)
 author = ReferenceField(User)
 tags = ListField(StringField(max_length=20, required=True), required=True)
 categories = ReferenceField(Categories), required=True)
 comments = IntField(default=0, required=True)

# 将会返回所有tags包含coding的文档
Posts.objects(tags='coding')

class Categories(Document):
 name = StringField(max_length=30, required=True)
 artnum = IntField(default=0, required=True)
 date = DateTimeField(default=datetime.now(), required=True)

class Posts(Document):

 title = StringField(max_length=100, required=True)
 content = StringField(required=True)
 tags = ListField(StringField(max_length=20, required=True), required=True)
 categories = ReferenceField(Categories)

cate =Categories(name="Linux")
cate.save()
post = Posts(title="Linuxzen.com", content="Linuxzen.com",tags=["Linux","web"], categories=cate)
post.save()

> cate = Posts.objects.all().first().categories
> cate

> cate.name

> cate = Categories.objects(name="Linux").first()
> Posts.objects(categories=cate)

class Posts(Document):

 title = StringField(max_length=100, required=True)
 content = StringField(required=True)
 tags = ListField(EmbeddedDocumentField('Tags')required=True)
 categories = ReferenceField(Categories)

class Tags(EmbeddedDocument):
name = StringField()
date = DateTimeField(default=datetime.now())

> tag = Tags(name="Linuxzen")
> post = Posts(title="Linuxzen.com", content="Linuxzen.com", tags=[tag], categories=cate)
> tag = Tags(name="mysite")
> post.tags.append(tag)
> post.save()
> tags = post.tags
> for tag in tags:
print tag.name

Linuxzen
mysite

 start = datetime(int(year), int(month), 1)
 if int(month) + 1 > 12:
  emonth = 1
  eyear = int(year) + 1
 else:
  emonth = int(month) + 1
  eyear = int(year)
 end = datetime(eyear, emonth, 1)
 articles = Posts.objects(date__gte=start, date__lt=end).order_by('-date')

# comments - skip 5, limit 10
Page.objects.fields(slice__comments=[5, 10])

# 也可以使用索引值分片

# limit 5
users = User.objects[:5]

# skip 5
users = User.objects[5:]

# skip 10, limit 15
users = User.objects[10:15]

# 更新嵌入文档comments字段by的值为joe的文档字段votes增加1
Page.objects(comments_by="joe").update(inc__votes=1)

# 更新嵌入文档comments字段by的值为joe的文档字段votes设置为1
Page.objects(comments_by="joe").update(set__votes=1)

其他技巧

#查询结果转换成字典
users_dict = User.objects().to_mongo()

# 排序,按日期排列
user = User.objects.order_by("date")

# 按日期倒序

user = User.objects.order_by("-date")