I'd like to warn or prevent a user from deleting an object instance which is referred to by other instances. Is there a nice way to do this?
我想警告或阻止用户删除其他实例引用的对象实例。有一个很好的方法来做到这一点？
One way would be to get a list of models which include the referent and then try reverse look-ups on them. Is there a way to get that list of models? Or is there a better way?
一种方法是获得包含指示物的模型列表，然后尝试对它们进行反向查找。有没有办法获得模型列表？或者，还有更好的方法？
While investigating the collector suggestion, I found some related information and wrote the following which finds the classes which have the referent as a foreign key:
在调查收集器的建议时，我发现了一些相关的信息，并编写了以下内容，找到了具有指示对象的类：
def find_related(cl, app):
"""Find all classes which are related to the class cl (in app) by
having it as a foreign key."""
from django.db import models
all_models = models.get_models()
ci_model = models.get_model(app, cl)
for a_model in all_models:
for f in a_model._meta.fields:
if isinstance(f, ForeignKey) and (f.rel.to == ci_model):
print a_model.__name__
Based on suggestion to use the code in collect:
根据建议使用收集中的代码：
def find_related(instance):
"""Find all objects which are related to instance."""
for related in instance._meta.get_all_related_objects():
acc_name = related.get_accessor_name()
referers = getattr(instance, acc_name).all()
if referers:
print related
1 个解决方案
#1
3
Django has something called Collector class. It is used by Django when performing a model deletion. What it does seems like exactly what you want. By calling collect() it finds all the references to the object in the model graph. Additionally it offers a way to delete all the found objects, with a delete() call.
Django有一个叫Collector类的东西。 Django在执行模型删除时使用它。它的作用似乎正是你想要的。通过调用collect（），它可以在模型图中找到对象的所有引用。此外，它提供了一种删除所有找到的对象的方法，并使用delete（）调用。
That said I've never used this class myself, I just know it exists. The API is somewhat convoluted, but if you're willing to dig into the internals of Django a little bit, it might save you a lot of coding.
那说我自己从未使用过这门课，我只知道它存在。 API有点令人费解，但是如果你愿意稍微深入研究一下Django的内部，它可能会为你节省很多代码。
#1
3
Django has something called Collector class. It is used by Django when performing a model deletion. What it does seems like exactly what you want. By calling collect() it finds all the references to the object in the model graph. Additionally it offers a way to delete all the found objects, with a delete() call.
Django有一个叫Collector类的东西。 Django在执行模型删除时使用它。它的作用似乎正是你想要的。通过调用collect（），它可以在模型图中找到对象的所有引用。此外，它提供了一种删除所有找到的对象的方法，并使用delete（）调用。
That said I've never used this class myself, I just know it exists. The API is somewhat convoluted, but if you're willing to dig into the internals of Django a little bit, it might save you a lot of coding.
那说我自己从未使用过这门课，我只知道它存在。 API有点令人费解，但是如果你愿意稍微深入研究一下Django的内部，它可能会为你节省很多代码。