Python 如何在Django中访问外键？

伙计们

我有以下代码：

class Model3D(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=300)
    description = models.CharField(max_length=500)
    original_Model = models.ForeignKey('Model3D', on_delete=models.CASCADE, null=True)
    creation_Date = models.DateTimeField(auto_now=True)
    stl_File = models.FileField(null=True, upload_to='models/stlFiles')
    scad_File = models.FileField(null=True, upload_to='models/scadFiles')
    parameter_id = models.ForeignKey('Parameter', on_delete=models.CASCADE, null=True)
    part_of = models.ForeignKey('Model3D', related_name="part_of_model3d", on_delete=models.CASCADE, null=True)
    picture_of_model = models.ForeignKey('Pictures', on_delete=models.CASCADE, null=True)

class Pictures(models.Model):
    id = models.AutoField(primary_key=True)
    picture = models.ImageField(upload_to='models/pictures', null=True)
    model_id = models.ForeignKey('Model3D', on_delete=models.CASCADE)

如您所见，Model3D与自身具有外键关系，因为3DModel可以由其他三个3DModel部件组成。因此，字段“部分”再次引用Model3D。 每个Model3D对象在pictures类中都有图片

我的问题是:

如何获取Model3D对象及其所有零件模型？ 如何获取Model3D对象及其零件模型的所有图片？

我尝试了很多与select_相关的东西，但都不起作用

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谢谢你的帮助

要获取所有嵌套模型的图片：

first_model_3d = Model3D.objects.get(id=model_id)
pictures = []
while first_model_3d.part_of:
    pictures.extend([picture for picture in Picture.objects.filter(model_id=first_model_3d)])
    first_model_3d = first_model_3d.part_of
print(pictures)

要从图片中获取嵌套模型，请执行以下操作：

picture = Picture.objects.get(id=picture_id)
model_3d = picture.model_id
model_3d_list = []
while model_3d:
    model_3d_list = model_3d
    model_3d = model_3d.part_of
print(model_3d_list)

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请添加您已尝试但未成功的内容！对不起，我没有密码了！