Non-database field in Django model

Question

Is it possible to have a field in a Django model which does not get stored in the database.
For example:

class Book(models.Model):
    title = models.CharFie         


        

Answer 1

To make it an instance variable (so each instance gets its own copy), you'll want to do this

class Book(models.Model):
    title = models.CharField(max_length=75)
    #etc

    def __init__(self, *args, **kwargs):
        super(Foo, self).__init__(*args, **kwargs)
        self.editable = False

Each Book will now have an editable that wont be persisted to the database

Answer 2

Creating a property on the model will do this, but you won't be able to query on it.

Answer 3

As long as you do not want the property to persist, I don't see why you can't create a property like you described. I actually do the same thing on certain models to determine which are editable.

class Email(EntryObj):
    ts = models.DateTimeField(auto_now_add=True)
    body = models.TextField(blank=True)
    user = models.ForeignKey(User, blank=True, null=True)
    editable = False
    ...


class Note(EntryObj):
    ts = models.DateTimeField(auto_now_add=True)
    note = models.TextField(blank=True)
    user = models.ForeignKey(User, blank=True, null=True)
    editable = True