为CREATE / UPDATE / DELETE /命令生成SQL，这在Django中是即时的

from django.db.models import sql

def generate_update_sql(queryset, update_kwargs):
    """Converts queryset with update_kwargs
    like : queryset.update(**update_kwargs) to UPDATE SQL"""

    query = queryset.query.clone(sql.UpdateQuery)
    query.add_update_values(update_kwargs)
    compiler = query.get_compiler(queryset.db)
    sql, params = compiler.as_sql()
    return sql % params

from django.db.models import sql

def generate_delete_sql(queryset):
    """Converts select queryset to DELETE SQL """
    query = queryset.query.chain(sql.DeleteQuery)
    compiler = query.get_compiler(queryset.db)
    sql, params = compiler.as_sql()
    return sql % params

from django.db.models import sql

def generate_create_sql(model, model_data):
    """Converts queryset with create_kwargs
    like if was: queryset.create(**create_kwargs) to SQL CREATE"""
    
    not_saved_instance = model(**model_data)
    not_saved_instance._for_write = True

    query = sql.InsertQuery(model)

    fields = [f for f in model._meta.local_concrete_fields if not isinstance(f, AutoField)]
    query.insert_values(fields, [not_saved_instance], raw=False)

    compiler = query.get_compiler(model.objects.db)
    sql, params = compiler.as_sql()[0]
    return sql % params

测试和使用

    def test_generate_update_sql_with_F(self):
        qs = Event.objects.all()
        update_kwargs = dict(description=F('slug'))
        result = generate_update_sql(qs, update_kwargs)
        sql = "UPDATE `api_event` SET `description` = `api_event`.`slug`"
        self.assertEqual(sql, result)

    def test_generate_create_sql(self):
        result = generate_create_sql(Event, dict(slug='a', app='b', model='c', action='e'))
        sql = "INSERT INTO `api_event` (`slug`, `app`, `model`, `action`, `action_type`, `description`) VALUES (a, b, c, e, , )"
        self.assertEqual(sql, result)

我为此开发了一个扩展，所以你可以很容易地在你的视图函数上放一个装饰器，看看有多少查询被执行了。

如何安装:

$ pip install django-print-sql

用作上下文管理器:

from django_print_sql import print_sql

# set `count_only` to `True` will print the number of executed SQL statements only
with print_sql(count_only=False):

  # write the code you want to analyze in here,
  # e.g. some complex foreign key lookup,
  # or analyzing a DRF serializer's performance

  for user in User.objects.all()[:10]:
      user.groups.first()

装饰:用作装饰:

from django_print_sql import print_sql_decorator


@print_sql_decorator(count_only=False)  # this works on class-based views as well
def get(request):
    # your view code here

Github: https://github.com/rabbit-aaron/django-print-sql

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。

另一个选项，请参阅本文中描述的settings.py中的日志记录选项

http://dabapps.com/blog/logging-sql-queries-django-13/

Debug_toolbar会降低开发服务器上每个页面的加载速度，而日志记录则不会，因此速度更快。输出可以转储到控制台或文件，所以UI不是很好。但是对于包含大量sql的视图，通过debug_toolbar调试和优化sql可能需要很长时间，因为每个页面加载都非常慢。

看一下debug_toolbar，它对调试非常有用。

文档和源代码可以在http://django-debug-toolbar.readthedocs.io/上找到。

下面基于https://code.djangoproject.com/ticket/17741:返回有效的SQL查询

def str_query(qs):
    """
    qs.query returns something that isn't valid SQL, this returns the actual
    valid SQL that's executed: https://code.djangoproject.com/ticket/17741
    """
    cursor = connections[qs.db].cursor()
    query, params = qs.query.sql_with_params()
    cursor.execute('EXPLAIN ' + query, params)
    res = str(cursor.db.ops.last_executed_query(cursor, query, params))
    assert res.startswith('EXPLAIN ')
    return res[len('EXPLAIN '):]