如何在Django中使数据库字段不可更改？

Question

Let's say I have Cars , CarTypes , and their BuildDates like this:

class Car(db.models):
    licence_name = models.CharField(max_length=64)
    car_type = models.ForeignKey(Type)

class Type(db.models):
    name = models.CharField(max_length=64)
    build_during = models.ForeignKey(BuildDate)   

class BuildDate(db.models):
    begin = models.DateField(null=True)
    end = models.DateField(null=True)

    class Meta(object):
        unique_together = (('begin', 'end'),)

I want to have the BuildDates in a seperate table such I can do faster queries and other stuff with Django-external tools.

Since BuildDates are unique but shared between CarTypes , I want to make sure this: If the BuildDate d0 of one CarType t1 is changed, the other CarTypes are not affected and they still share the identical BuildDate d0 – but not with t1 which now has d1 . I believe it is necessary to create a new BuildDate d1 for that CarType t1 . Is there a recommended or recommendable way to do this?

Answer 1

Use "editable" attribute. When you set "False", element will not be shown in the admin, that is, you can't change its value.

eg

licence_name = models.CharField(max_length=64, editable=False)