是否有一种方法可以在执行查询时显示Django正在运行的SQL ?


当前回答

我相信这应该工作,如果你使用PostgreSQL:

from django.db import connections
from app_name import models
from django.utils import timezone

# Generate a queryset, use your favorite filter, QS objects, and whatnot.
qs=models.ThisDataModel.objects.filter(user='bob',date__lte=timezone.now())

# Get a cursor tied to the default database
cursor=connections['default'].cursor()

# Get the query SQL and parameters to be passed into psycopg2, then pass
# those into mogrify to get the query that would have been sent to the backend
# and print it out. Note F-strings require python 3.6 or later.
print(f'{cursor.mogrify(*qs.query.sql_with_params())}')

其他回答

使用django.db.connection.queries查看查询

from django.db import connection
print(connection.queries)

访问QuerySet对象上的原始SQL查询

 qs = MyModel.objects.all()
 print(qs.query)

如果您需要为一些自定义SQL重用查询,还有另一种非常有用的方法。我曾在一个分析应用程序中使用过这种方法,它远远超出了Django的ORM所能轻松完成的范围,所以我将ORM生成的SQL作为子查询包含进来。

from django.db import connection
from myapp.models import SomeModel

queryset = SomeModel.objects.filter(foo='bar')

sql_query, params = queryset.query.as_sql(None, connection)

这将为您提供带有占位符的SQL,以及可以使用的带有查询参数的元组。你可以直接把它传递给DB:

with connection.connection.cursor(cursor_factory=DictCursor) as cursor:
    cursor.execute(sql_query, params)
    data = cursor.fetchall()

我把这个函数放在我项目中的一个应用程序的util文件中:

import logging
import re

from django.db import connection

logger = logging.getLogger(__name__)

def sql_logger():
    logger.debug('TOTAL QUERIES: ' + str(len(connection.queries)))
    logger.debug('TOTAL TIME: ' + str(sum([float(q['time']) for q in connection.queries])))

    logger.debug('INDIVIDUAL QUERIES:')
    for i, query in enumerate(connection.queries):
        sql = re.split(r'(SELECT|FROM|WHERE|GROUP BY|ORDER BY|INNER JOIN|LIMIT)', query['sql'])
        if not sql[0]: sql = sql[1:]
        sql = [(' ' if i % 2 else '') + x for i, x in enumerate(sql)]
        logger.debug('\n### {} ({} seconds)\n\n{};\n'.format(i, query['time'], '\n'.join(sql)))

然后,当需要时,我只是导入它,并从任何上下文(通常是视图)调用它是必要的,例如:

# ... other imports
from .utils import sql_logger

class IngredientListApiView(generics.ListAPIView):
    # ... class variables and such

    # Main function that gets called when view is accessed
    def list(self, request, *args, **kwargs):
        response = super(IngredientListApiView, self).list(request, *args, **kwargs)

        # Call our function
        sql_logger()

        return response

在模板之外这样做很好,因为如果你有API视图(通常是Django Rest框架),它也适用于模板。

你可以使用连接。在Django中运行原始SQL查询,如下所示:

# "store/views.py"

from django.db import transaction
from .models import Person
from django.db import connection
from django.http import HttpResponse

@transaction.atomic
def test(request):
    Person.objects.create(name="John") # INSERT
    
    qs = Person.objects.select_for_update().get(name="John") # SELECT FOR UPDATE
    qs.name = "Tom"
    qs.save() # UPDATE
    qs.delete() # DELETE
                 
    for query in connection.queries: # Here
        print(query)

    return HttpResponse("Test")

然后,原始查询打印在控制台,如下所示:

{'sql': 'INSERT INTO "store_person" ("name") VALUES (\'John\') RETURNING "store_person"."id"', 'time': '0.000'}
{'sql': 'SELECT "store_person"."id", "store_person"."name" FROM "store_person" WHERE "store_person"."name" = \'John\' LIMIT 21 FOR UPDATE', 'time': '0.000'}      
{'sql': 'UPDATE "store_person" SET "name" = \'Tom\' WHERE "store_person"."id" = 179', 'time': '0.000'}
{'sql': 'DELETE FROM "store_person" WHERE "store_person"."id" IN (179)', 'time': '0.000'}
[24/Dec/2022 06:29:32] "GET /store/test/ HTTP/1.1" 200 9

然后,把reset_queries()放在Person.objects.select_for_update()之后,如果你想只得到UPDATE和DELETE查询,而没有INSERT和SELECT FOR UPDATE查询,如下所示:

# "store/views.py"

from django.db import transaction
from .models import Person
from django.db import reset_queries
from django.db import connection
from django.http import HttpResponse

@transaction.atomic
def test(request):
    Person.objects.create(name="John") # INSERT
    
    qs = Person.objects.select_for_update().get(name="John") # SELECT FOR UPDATE
    reset_queries() # Here
    qs.name = "Tom"
    qs.save() # UPDATE
    qs.delete() # DELETE
                 
    for query in connection.queries: # Here
        print(query)

    return HttpResponse("Test")

然后,只打印UPDATE和DELETE查询,不打印INSERT和SELECT FOR UPDATE查询,如下所示:

{'sql': 'UPDATE "store_person" SET "name" = \'Tom\' WHERE "store_person"."id" = 190', 'time': '0.000'}
{'sql': 'DELETE FROM "store_person" WHERE "store_person"."id" IN (190)', 'time': '0.000'}
[24/Dec/2022 07:00:01] "GET /store/test/ HTTP/1.1" 200 9

请参阅文档常见问题:“如何查看Django正在运行的原始SQL查询?”

django.db.connection.queries包含一个SQL查询列表:

from django.db import connection
print(connection.queries)

queryset也有一个包含要执行的查询的query属性:

print(MyModel.objects.filter(name="my name").query)

注意,查询的输出不是有效的SQL,因为:

Django从未真正插入参数:它将查询和参数分别发送到数据库适配器,由数据库适配器执行适当的操作。

来自Django错误报告#17741。

因此,不应该将查询输出直接发送到数据库。

如果你需要重置查询,例如,查看在给定的时间内有多少查询在运行,你可以使用reset_queries from django.db:

from django.db import reset_queries
from django.db import connection

reset_queries()
# Run your query here
print(connection.queries)
>>> []