如何使用存储在字段值中的正则表达式执行正则表达式查找？ [英] How can I perform a regex lookup with the regular expression being stored in a field value?

问题描述

给出以下模型：

from django.db import models
from django.conf import settings

class UserMessage(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL)
    path = models.CharField(max_length=255)
    message = models.TextField()

并给出以下模型实例：

UserMessage.objects.create(
    user=request.user,
    path='^/dashboard/(.*)+$',
    message='Welcome to your dashboard!'
)

我想能够针对UserMessage.path的值执行当前请求路径的查找。这意味着我需要在查询的右侧添加路径，例如：

I want to be able to perform a lookup of the current request path against the value of UserMessage.path. This means that I need to have 'path' on the right side of my query, e.g.:

SELECT * FROM user_message WHERE '/dashboard/foo/' ~ path;

但是，Django ORM的正则表达式查找产生相反的顺序，例如：

However, the Django ORM's regexp lookup produces the opposite order, e.g.:

SELECT * FROM user_message WHERE path ~ '/dashboard/foo/';

是否有一种方法可以使用ORM查找轻松地将其反转为所需的结果？还是更适合.extra（）或自定义查找表达式？

Is there a way I can easily reverse this for my desired result, using an ORM lookup? Or is this better suited for a .extra() or custom lookup expression?

推荐答案

extra（）

UserMessage.objects.extra(where=['%s ~ path'], params=[request.path])

自定义查找

models.py

from django.db.models import Lookup

@models.CharField.register_lookup
class NotEqual(Lookup):
    lookup_name = 'test'

    def as_postgresql(self, compiler, connection):
        lhs, lhs_params = self.process_lhs(compiler, connection)
        rhs, rhs_params = self.process_rhs(compiler, connection)
        params = lhs_params + rhs_params
        return '%s ~ %s' % (rhs, lhs), params

用法： UserMessages.objects.get（path__test = request.path）

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