Question

我正在使用Django 1.6并使用模型继承。标题可能令人困惑，这是解释;

class ParentModel(models.Model)
    class Meta:
        db_table = "parent_model"

    my_field=.....

class ProxyModelOfParentModel(ParentModel)
    class Meta:
        proxy=True

    objects=CustomManager()


class InheritedModel(ParentModel)
    class Meta:
        db_table = "inherited_model"

    my_extra_field=.....

假设这些是我们的模型。当我尝试在ParentModel上按 my_extra_field 进行过滤时，我会这样做;

ParentModel.objects.filter(inheritedmodel__my_extra_field='test')

但是，我想过滤代理模型，比如;

ProxyModelOfParentModel.objects.filter(inheritedmodel__my_extra_field='test')

当我运行它时，它无法在代理模型中找到字段 inheritedmodel 。这也可能是Django中的错误，我不知道。不知何故，当我尝试过滤代理模型时，django现在可以正确构建查询集。

为什么我使用代理模型而不是使用父模型，在不同的管理员中使用代理模型。当我在管理员list_filter中提供密钥时，我遇到了FieldDoesNotExists错误。

有没有办法过滤我提到的？谢谢！

Answer 1

正如我所提到的，这是因为代理模型初始化的django实现。我不知道，这是错误与否，但我需要以某种方式解决这个问题。我发现这是因为模型中的一部分_meta初始化。 django.db.models.options.py中的这部分是我注释掉的部分导致了这个问题

def _fill_related_objects_cache(self):
    cache = SortedDict()
    parent_list = self.get_parent_list()
    for parent in self.parents:
        for obj, model in parent._meta.get_all_related_objects_with_model(include_hidden=True):
            #THIS PART WAS CAUSING THE PROBLEM
            # if (obj.field.creation_counter < 0 or obj.field.rel.parent_link) and obj.model not in parent_list:
            #     continue
            if not model:
                cache[obj] = parent
            else:
                cache[obj] = model
    # Collect also objects which are in relation to some proxy child/parent of self.
    proxy_cache = cache.copy()
    for klass in get_models(include_auto_created=True, only_installed=False):
        if not klass._meta.swapped:
            for f in klass._meta.local_fields:
                if f.rel and not isinstance(f.rel.to, six.string_types) and f.generate_reverse_relation:
                    if self == f.rel.to._meta:
                        cache[f.related] = None
                        proxy_cache[f.related] = None
                    elif self.concrete_model == f.rel.to._meta.concrete_model:
                        proxy_cache[f.related] = None
    self._related_objects_cache = cache
    self._related_objects_proxy_cache = proxy_cache

我只是覆盖我的父模型的Options类和元类，而不是覆盖Django本身就像;

class CustomProxyModelOptions(Options):
    def _fill_related_objects_cache(self):
        cache = SortedDict()
        parent_list = self.get_parent_list()
        for parent in self.parents:
            for obj, model in parent._meta.get_all_related_objects_with_model(include_hidden=True):
                if not model:
                    cache[obj] = parent
                else:
                    cache[obj] = model
        # Collect also objects which are in relation to some proxy child/parent of self.
        proxy_cache = cache.copy()
        for klass in get_models(include_auto_created=True, only_installed=False):
            if not klass._meta.swapped:
                for f in klass._meta.local_fields:
                    if f.rel and not isinstance(f.rel.to, six.string_types) and f.generate_reverse_relation:
                        if self == f.rel.to._meta:
                            cache[f.related] = None
                            proxy_cache[f.related] = None
                        elif self.concrete_model == f.rel.to._meta.concrete_model:
                            proxy_cache[f.related] = None
        self._related_objects_cache = cache
        self._related_objects_proxy_cache = proxy_cache


class ProxyModelMeta(ModelBase):
    def __new__(cls, *args, **kwargs):
        model = super(ProxyModelMeta, cls).__new__(cls, *args, **kwargs)
        model._meta.__class__ = CustomProxyModelOptions
        return model

class ParentModel(models.Model)
    class Meta:
        db_table = "parent_model"

    my_field=.....

class ProxyModelOfParentModel(ParentModel)
    __metaclass__= ProxyModelMeta
    class Meta:
        proxy=True

    objects=CustomManager()


class InheritedModel(ParentModel)
    class Meta:
        db_table = "inherited_model"

    my_extra_field=.....

现在，我可以过滤;

ProxyModelOfParentModel.objects.filter(inheritedmodel__my_extra_field='test')

通过代理模型父级的继承模型字段过滤代理模型。

1 个答案: