如何在 Django 中获取 COUNT 查询

Question

To get a query in django I can do:

>>> print User.objects.all().query
SELECT `auth_user`.`id`, `auth_user`.`username`, `auth_user`.`first_name`, `auth_user`.`last_name`, `auth_user`.`email`, `auth_user`.`password`, `auth_user`.`is_staff`, `auth_user`.`is_active`, `auth_user`.`is_superuser`, `auth_user`.`last_login`, `auth_user`.`date_joined` 
FROM `auth_user`

However, how would I get the query it builds when doing a COUNT?

>>> User.objects.all().count().query
Traceback (most recent call last):
  File "<console>", line 1, in <module>
AttributeError: 'int' object has no attribute 'query'

Answer 1

From docs:

count()

Returns an integer representing the number of objects in the database matching the QuerySet.

Thus, you can't.

However, you can make use of django.db.connection.queries in order to see and access the queries that are made by the current process.

>>> from django.db import connection
>>> User.objects.count()
>>> print connection.queries

Note that, this works only when DEBUG=True and you can't access them from another process, you can't share between views.

The best option would be to use the Django debug toolbar .

Answer 2

CaptureQueriesContext will grab the query for you after it's run, and I think works without DEBUG :

from django.test.utils import CaptureQueriesContext
with CaptureQueriesContext(conn) as queries:
    value = User.objects.count()
    print(queries.captured_queries[0]['sql'])

Answer 3

如果打开了 DEBUG，您始终可以从连接对象中获取 Django 执行的查询，如文档中所述。

Answer 4

如果您只想查看查询，只需安装 Django 调试工具栏： https : //github.com/django-debug-toolbar/django-debug-toolbar