Mongoengine 简明教程

MongoEngine - Query Operators

除了使用 = 操作符检查是否相等外，MongoEngine 中还定义了以下逻辑操作符。

In addition to = operator to check equality, the following logical operators are defined in MongoEngine.

ne

not equal to

lt

less than

lte

less than or equal to

gt

greater than

gte

greater than or equal to

not

negate a standard check, may be used before other operators

in

value is in list

nin

value is not in list

mod

value % x == y, where x and y are two provided values

all

every item in list of values provided is in array

size

the size of the array is

exists

value for field exists

这些运算符必须附加到带有双下划线 __ 的字段名。

These operators must be attached to field name with double underscore __.

要使用大于运算符 (gt)，使用以下格式 -

To use greater than (gt) operator, use the following format −

#using greater than operator
for product in products.objects(price__gt=10000):
   print ('ID:',product.ProductID, 'Name:',product.Name, 'Price:',product.price)

Output

ID: 1 Name: Laptop Price: 25000
ID: 2 Name: TV Price: 50000
ID: 5 Name: Printer Price: 12500

in 运算符类似于 Python 的 in 运算符。对于与列表中名称相匹配的产品名称，使用以下代码 -

The in operator is like Python’s in operator. For name of product matching with names in list, the following code is used −

for product in products.objects(Name__in=['TV', 'Printer']):
print ('ID:',product.ProductID, 'Name:',product.Name, 'Price:',product.price)

Output

ID: 2 Name: TV Price: 50000
ID: 5 Name: Printer Price: 12500

您可以使用以下运算符作为应用于查询的正则表达式的快捷方式 -

You can use following operators as shortcut for regex expressions for applying filter to queries −

exact

string field exactly matches value

iexact

string field exactly matches value (case insensitive)

contains

string field contains value

icontains

string field contains value (case insensitive)

startswith

string field starts with value

istartswith

string field starts with value (case insensitive)

endswith

string field ends with value

iendswith

string field ends with value (case insensitive)

match

performs an $elemMatch so you can match an entire document within an array

例如，以下代码将打印名称中包含 'o' 的产品详细信息 -

For example, the following code prints product details for name containing ‘o’ in name −

for product in products.objects(Name__contains='o'):
   print ('ID:',product.ProductID, 'Name:',product.Name, 'Price:',product.price)

Output

ID: 1 Name: Laptop Price: 25000
ID: 3 Name: Router Price: 2000

在另一个字符串查询示例中，以下代码显示以 'er' 结尾的名称 -

In another example of string query, the following code displays name ending with ‘er’−

for product in products.objects(Name__endswith='er'):
   print ('ID:',product.ProductID, 'Name:',product.Name, 'Price:',product.price)

Output

ID: 3 Name: Router Price: 2000
ID: 4 Name: Scanner Price: 5000
ID: 5 Name: Printer Price: 12500