Question

我在Django ModelAdmin列表视图中优化了get_queryset：

.only('field1', 'field2',)
.select_related('rel1',)

这些优化与get_object更改视图所需的不同：

.only('field1', 'field2', 'field3',)
.select_related('rel1__rel2', 'rel3',)
.prefetch_related(...)

事情是，get_queryset and get_object are coupled：

class BaseModelAdmin(...):

  ...

  def get_object(self, request, object_id, from_field=None):
      """
      Returns an instance matching the field and value provided, the primary
      key is used if no field is provided. Returns ``None`` if no match is
      found or the object_id fails validation.
      """
      queryset = self.get_queryset(request)
      model = queryset.model
      field = model._meta.pk if from_field is None else model._meta.get_field(from_field)
      try:
          object_id = field.to_python(object_id)
          return queryset.get(**{field.name: object_id})
      except (model.DoesNotExist, ValidationError, ValueError):
          return None

如何在不必复制/粘贴上面的所有锅炉板的情况下覆盖get_queryset？

Answer 1

您的用例并不常见，因此我认为没有任何明智的方法可以在不重写get_object的情况下实现您的需求。我会做这样的事情：

# A parameter with default False value shouldn't screw things up
def get_queryset(request, for_object=False):
    qs = super(YourModelAdmin, self).get_queryset(request)
    if for_object:
        qs = qs.select_related('rel1__rel2', 'rel3')
        qs = .prefetch_related('rel4', 'rel5')
        return qs.only('field1', 'field2', 'field3')
    else:
        qs = qs.select_related('rel1')
        return qs.only('field1', 'field2')

def get_object(self, request, object_id, from_field=None):
    # Don't forget to add new param here
    queryset = self.get_queryset_for_object(request, for_object=True)
    model = queryset.model
    field = model._meta.pk if from_field is None else model._meta.get_field(from_field)
    try:
        object_id = field.to_python(object_id)
        return queryset.get(**{field.name: object_id})
    except (model.DoesNotExist, ValidationError, ValueError):
        return None

Answer 2

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Django ModelAdmin get_object optimization

2 个答案: