DJANGO模型：是否有可能使用经理使用特定字段上的特定字段来强制IContains？

Question

假设我有一个与此类似的字符串字段的模型，

class Product(models.Model):
    upc = models.CharField(max_length=12, blank=False, null=False)

这是可以构建模型管理器或类似的模型，而每次我使用product.objects.get/product.objects.filter时它覆盖默认查找，以强迫搜索/过滤器的行为，就像我使用过icontains一样？

如下：

Product.objects.get(upc="012345678902")
Product.objects.filter(upc="012345678902")

默认情况下的行为会如下：

Product.objects.get(upc__icontains="012345678902")
Product.objects.filter(upc__icontains="012345678902")

Answer 1

您可以自定义查询管理器或QuerySet，并覆盖GET/过滤器方法。下面的演示可以告诉您如何自定义查询管理器实施强制IContains。

from django.db import models


class ForceIContainsManager(models.Manager):
    force_icontains_fields = None

    def __init__(self, *args, **kwargs) -> None:
        if "force_icontains_fields" in kwargs:
            self.force_icontains_fields = kwargs.pop("force_icontains_fields")
        super(ForceIContainsManager, self).__init__(*args, **kwargs)

    def get(self, *args, **kwargs):
        kwargs = self._force_icontains(**kwargs)
        return super(ForceIContainsManager, self).get(*args, **kwargs)

    def filter(self, *args, **kwargs):
        kwargs = self._force_icontains(**kwargs)
        return super(ForceIContainsManager, self).filter(*args, **kwargs)

    def _force_icontains(self, **kwargs):
        """
        replace field in force_icontains_fields to icontains style
        """
        if not self.force_icontains_fields:
            return kwargs
        for field in self.force_icontains_fields:
            if field in kwargs:
                v = kwargs.pop(field)
                new_field_name = '%s__icontains' % field
                kwargs[new_field_name] = v
        return kwargs


class YourModel(models.Model):
    # define a another manager, YourModel.manager will force icontains on certain fields
    manager = ForceIContainsManager(
        force_icontains_fields=["field1", "field2"])
    # if you want use YourModel.objects, you should uncomment below
    # objects = ForceIContainsManager(force_icontains_fields=["field1", "field2"])
    pass


# check sql
print(YourModel.manager.filter(field1='test').query)

更自定义可以看到 https：/ 1400/custom-managers and QuerySets

QueryManager在QuerySet中使用baseManager.from_queryset的所有方法代理所有方法，选择一个已经足够了。