Django datetime issues (


I have the below db model:

from datetime import datetime    

class TermPayment(models.Model):
    # I have excluded fields that are irrelevant to the question
    date = models.DateTimeField(, blank=True)

I add a new instance by using the below:

tp = TermPayment.objects.create(**kwargs)

My issue: all records in database have the same value in date field, which is the date of the first payment. After the server restarts, one record has the new date and the other records have the same as the first. It looks as if some data is cached, but I can’t find where.

database: mysql 5.1.25

django v1.1.1

Asked By: Shamanu4



it looks like is being evaluated when the model is defined, and not each time you add a record.

Django has a feature to accomplish what you are trying to do already:

date = models.DateTimeField(auto_now_add=True, blank=True)


date = models.DateTimeField(, blank=True)

The difference between the second example and what you currently have is the lack of parentheses. By passing without the parentheses, you are passing the actual function, which will be called each time a record is added. If you pass it, then you are just evaluating the function and passing it the return value.

More information is available at Django’s model field reference

Answered By: Carson Myers

From the documentation on the django model default field:

The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.

Therefore following should work:

date = models.DateTimeField(,blank=True)
Answered By: mykhal

The is evaluated when the class is created, not when new record is being added to the database.

To achieve what you want define this field as:

date = models.DateTimeField(auto_now_add=True)

This way the date field will be set to current date for each new record.

Answered By: Bartosz

From the Python language reference, under Function definitions:

Default parameter values are evaluated when the function definition is executed. This means that the expression is evaluated once, when the function is defined, and that that same “pre-computed” value is used for each call.

Fortunately, Django has a way to do what you want, if you use the auto_now argument for the DateTimeField:

date = models.DateTimeField(auto_now=True)

See the Django docs for DateTimeField.

Answered By: ars is being evaluated once, when your class is instantiated. Try removing the parenthesis so that the function is returned and THEN evaluated. I had the same issue with setting default values for my DateTimeFields and wrote up my solution here.

Answered By: David

The answer to this one is actually wrong.

Auto filling in the value (auto_now/auto_now_add isn’t the same as default). The default value will actually be what the user sees if its a brand new object. What I typically do is:

date = models.DateTimeField(, editable=False,)

Make sure, if your trying to represent this in an Admin page, that you list it as ‘read_only’ and reference the field name

read_only = 'date'

Again, I do this since my default value isn’t typically editable, and Admin pages ignore non-editables unless specified otherwise. There is certainly a difference however between setting a default value and implementing the auto_add which is key here. Test it out!

Answered By: Andrew Harris

David had the right answer. The parenthesis () makes it so that the callable is called every time the model is evaluated. If you remove the () from (or, if using the naive datetime object) to make it just this:

Then it will work as you expect:
New objects will receive the current date when they are created, but the date won’t be overridden every time you do makemigrations/migrate.

I just encountered this. Much thanks to David.

Answered By: MicahT

Instead of using you should be really using from django.utils.timezone import now


so go for something like this:

from django.utils.timezone import now

created_date = models.DateTimeField(default=now, editable=False)
Answered By: andilabs

In Django 3.0 auto_now_add seems to work with auto_now


Answered By: Bosco Oludhe

if you need only DateField try this

date = models.DateField(auto_now=False, auto_now_add=False, null=True, blank=True)

if you need Both Date and Time try this

date = models.DateTimeField(auto_now_add=True, null=True, blank=True)
Answered By: Manoj Parmar
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