tracker.py 文件源码

def init_deferred_fields(self):
        self.instance._deferred_fields = set()
        if hasattr(self.instance, '_deferred') and not self.instance._deferred:
            return

        class DeferredAttributeTracker(DescriptorMixin, DeferredAttribute):
            tracker_instance = self

        class FileDescriptorTracker(DescriptorMixin, FileDescriptor):
            tracker_instance = self

            def _get_field_name(self):
                return self.field.name

        if django.VERSION >= (1, 8):
            self.instance._deferred_fields = self.instance.get_deferred_fields()
            for field in self.instance._deferred_fields:
                if django.VERSION >= (1, 10):
                    field_obj = getattr(self.instance.__class__, field)
                else:
                    field_obj = self.instance.__class__.__dict__.get(field)
                if isinstance(field_obj, FileDescriptor):
                    field_tracker = FileDescriptorTracker(field_obj.field)
                    setattr(self.instance.__class__, field, field_tracker)
                else:
                    field_tracker = DeferredAttributeTracker(
                        field_obj.field_name, None)
                    setattr(self.instance.__class__, field, field_tracker)
        else:
            for field in self.fields:
                field_obj = self.instance.__class__.__dict__.get(field)
                if isinstance(field_obj, DeferredAttribute):
                    self.instance._deferred_fields.add(field)

                    # Django 1.4
                    if django.VERSION >= (1, 5):
                        model = None
                    else:
                        model = field_obj.model_ref()

                    field_tracker = DeferredAttributeTracker(
                        field_obj.field_name, model)
                    setattr(self.instance.__class__, field, field_tracker)