Django queryset模型应用于现场 [英] Django queryset model apply function in field
本文介绍了Django queryset模型应用于现场的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
可以在Django模型中使用where子句中的字段来模拟此查询SQL。
我的查询SQL
pre>
SELECT id,name,email
来自学生的md5(cast(id as text))='e4da3b7fbbce2345d7772b0674a318d5';
我的Django模型。
class学生(models.Model):
name = models.CharField(max_length = 50)
email = models
Django中的方法 - 的值 where_filter
是值字段的MD5 id
/
pk
。
where_filter ='e4da3b7fbbce2345d7772b0674a318d5'
Students.objects.get(pk = where_filter)
Students.objects.filter(pk = where_filter)
谢谢。
解决方案
您可以使用自定义转换类。
如下所示:
class Md5Value(Transform):
lookup_name ='md5'
output_field = CharField()
def as_sql(self,compiler,connectino):
lhs,params =编译器(自定义)
返回MD5(cast(%s为文本))%lhs,params
AutoField.register_lookup(MD5Value)
现在你可以做:
where_filter ='e4da3b7fbbce2345d7772b0674a318d5'
Students.objects.get(pk__md5 = where_filter)
It is possible simulate this query SQL in Django models using function in field in where clause.
My Query SQL
SELECT id, name, email
FROM students where md5(cast(id as text)) = 'e4da3b7fbbce2345d7772b0674a318d5';
My Django model.
class Students(models.Model):
name = models.CharField(max_length=50)
email = models
Methods in Django - Value of where_filter
is a MD5 of value field id
/pk
.
where_filter = 'e4da3b7fbbce2345d7772b0674a318d5'
Students.objects.get(pk=where_filter)
Students.objects.filter(pk=where_filter)
Thanks.
解决方案
You can do this with a custom Transform class.
Something like:
class Md5Value(Transform):
lookup_name = 'md5'
output_field = CharField()
def as_sql(self, compiler, connectino):
lhs, params = compiler.compile(self.lhs)
return "MD5(cast(%s as text))" % lhs, params
AutoField.register_lookup(MD5Value)
Now you can do:
where_filter = 'e4da3b7fbbce2345d7772b0674a318d5'
Students.objects.get(pk__md5=where_filter)
这篇关于Django queryset模型应用于现场的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文