Django每个模型必须有一个date_created和date_modified字段

Question

Is there a way to have a date_created and date_modified fields for each and every model in models.py?

I would like to have these two fields for each table being created so that I will be able to know when a row is created or updated.

But I don't want to have them shown in my models.py specifically for each model.

Is there a way to do this?

Answer 1

You could for example define an abstract supermodel. Like:

class (models.Model):
     = models.DateTimeField(auto_now_add=True)
     = models.DateTimeField(auto_now=True)

    class Meta:
        

Here we use auto_now_add=True and auto_now , these parameters will even ensure that the date_created is automatically set to the timestamp when the object was created, and date_modified will automatically get updated when you update the object in the database.

Then you can subclass it. For example for a model called SomeModel :

class SomeModel:
    name = models.CharField(max_length=128)

Making the model abstract = True is rather important (well it can still work without making it abstract, but it will make the database quite messy and less efficient). By specifying this is abstract, it will add the two columns to every model that inherits from this model. In case you do not make it abstract, Django will construct a new table, but typically this will make queries less efficient.

Since you here add columns to (potentially a large amount of) models, this will require a migration that will add the columns to the database level. In case there is already data stored in the application, you will need to find a way to resolve the columns for rows that already exist (for example set it to NOW() , or to the beginning of times).