Django：无法在同一模型文件中访问模型类的_meta

Question

我有工厂模型和方法 get_plant_measurement_field_details 返回以＆＃39;测量＆＃39; 以便我可以使用其名称和详细名称来创建另一个名为 PlantModelMeasurementRange

的模型

class Plant(models.Model):
    model = models.ForeignKey(PlantModel, null=True, blank=True)
    measurement_outlet_length = models.FloatField(
        verbose_name=_('Outlet length in cm'),
        blank=True,
        null=True
    )
    measurement_outlet_width = models.FloatField(
        verbose_name=_('Outlet width in cm'),
        blank=True,
        null=True
    )


def get_plant_measurement_field_details():
    fields = Plant._meta.get_fields()
    measurement_field_details = []
    for field in fields:
        if field.name.startswith('measurement'):
            measurement_field_details.append(
                {
                    'name': field.name,
                    'verbose_name': field.verbose_name
                }
            )
    return measurement_field_details

class PlantModelMeasurementRange(models.Model):
    model = models.OneToOneField(PlantModel, on_delete=models.CASCADE, related_name='range')

for field in get_plant_measurement_field_details()[0]:
    models.FloatField(
        verbose_name='Maximum Value of %s' % 
field.get('verbose_name').lower()
    ).contribute_to_class(
        PlantModelMeasurementRange, '%s_max' % field.get('name').lower()
    )

但是在runserver上它会出现异常：

django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.

有没有更好的方法来解决这个问题。 感谢