mongoengine数据查询

模型示例：

class Address(EmbeddedDocument):
    country = StringField(require=True)
    
class User(Document):
    email = StringField(required=True)
    first_name = StringField(max_length=50)
    last_name = StringField(max_length=50)
    address = ListField(EmbeddedDocumentField(Address))
   
class Post(Document):
    title = StringField(max_length=120, required=True)
    author = ReferenceField(User)
    tags = ListField(StringField(max_length=30))

1. 简单查询

Post.objects(title='python')   查看title等于python的post
Post.objects(title__icontains='python')    忽略大小写，title中包含python的post
Post.objects(title__contains='python')     不忽略大小写

字符串类型匹配：

• exact – 精确匹配
• iexact – 精确匹配，但是忽略大小写
• contains – 包含
• icontains – 包含，忽略大小写
• startswith – 匹配开头
• istartswith – 匹配开头，忽略大小写
• endswith – 匹配结尾
• iendswith – 匹配结尾，忽略大小写
• match – performs an $elemMatch so you can match an entire document within an array

数值型匹配：

• ne – 不等于
• lt – 小于
• lte – 小于等于
• gt – 大于
• gte – 大于等于
• not – negate a standard check, may be used before other operators (e.g.Q(age__not__mod=(5, 0)))
• in – 属于
• nin – 不属于
• mod – value % x == y, where x and y are two provided values
• all – every item in list of values provided is in array
• size – 计算arry的大小
• exists – 字段的值是否存在

2.关联查询

• Fields on embedded documents

User.objects(address__country='USA')       # 查询地址中的国家名字等于USA的用户
User.objects(address__country__icontains='USA')    # 查询地址中的国家名字包含USA的用户

3.list字段查询

Post.objects(tags='python')     # 查询tags中包含python的post
Post.objects(tags__0='python')     # 匹配tags中第一个值为python的post

4.原始查询语句

Post.objects(__raw__={"tags": 'python'})