在django raw sql中传递列表或元组作为参数

Question

我有一个列表,并希望通过django原始sql传递.

这是我的清单

region = ['US','CA','UK']

我在这里粘贴原始sql的一部分.

results = MMCode.objects.raw('select assigner, assignee from mm_code where date between %s and %s and country_code in %s',[fromdate,todate,region])

现在它给出了以下错误,当我在django python shell中执行它时

Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 1412, in __iter__
query = iter(self.query)
File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 73, in __iter__
self._execute_query()
File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 87, in _execute_query
self.cursor.execute(self.sql, self.params)
File "/usr/local/lib/python2.6/dist-packages/django/db/backends/util.py", line 15, in execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python2.6/dist-packages/django/db/backends/mysql/base.py", line 86, in execute
return self.cursor.execute(query, args)
File "/usr/lib/pymodules/python2.6/MySQLdb/cursors.py", line 166, in execute
self.errorhandler(self, exc, value)
File "/usr/lib/pymodules/python2.6/MySQLdb/connections.py", line 35, in defaulterrorhandler
raise errorclass, errorvalue
DatabaseError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1")

我也尝试过传递元组,但没有用.有人能帮我吗.

谢谢Vikram

Answer 1

至少对于PostgreSQL,list/tuple参数在SQL中被转换为数组,例如

ARRAY['US', 'CA', 'UK']

当它插入到给定的查询中时,会导致无效的SQL -

SELECT assigner, assignee FROM mm_code
WHERE date BETWEEN '2014-02-01' AND '2014-02-05'
AND country_code IN ARRAY['US', 'CA', 'UK']

但是,SQL中的'in'子句在逻辑上等同于 -

SELECT assigner, assignee FROM mm_code
WHERE date BETWEEN %s AND %s
AND country_code = ANY(%s)

...当此查询填充参数时,生成的SQL有效并且有效 -

SELECT assigner, assignee FROM mm_code
WHERE date BETWEEN '2014-02-01' AND '2014-02-05'
AND country_code = ANY(ARRAY['US', 'CA', 'UK'])

我不确定这是否适用于其他数据库,以及这是否会改变查询的计划方式.

Answer 2

将列表转换为元组确实在Postgres中有效,尽管相同的代码在sqlite3下失败,DatabaseError: near "?": syntax error因此它似乎是特定于后端的.您的代码行将变为:

results = MMCode.objects.raw('select assigner, assignee from mm_code where date between %s and %s and country_code in %s',[fromdate,todate,tuple(region)])

我在一个干净的Django 1.5.1项目中使用bar/models.py中的以下内容测试了这个:

from django.db import models

class MMCode(models.Model):
    assigner = models.CharField(max_length=100)
    assignee = models.CharField(max_length=100)
    date = models.DateField()
    country_code = models.CharField(max_length=2)

然后在壳:

>>> from datetime import date
>>> from bar.models import MMCode
>>> 
>>> regions = ['US', 'CA', 'UK']
>>> fromdate = date.today()
>>> todate = date.today()
>>> 
>>> results = MMCode.objects.raw('select id, assigner, assignee from bar_mmcode where date between %s and %s and country_code in %s',[fromdate,todate,tuple(regions)])
>>> list(results)
[]

(请注意,此处稍微更改了查询行,以使用Django创建的默认表名,并id在输出中包含该列,以便ORM不会抱怨)