Django DateTimeField() casuing TypeError ('datetime.timedelta' object is not callable)

Question

I am trying to get differenc of two Datetiemfield in Djago. I have tried overriding the default save() but still getting error.

models.py

class Sample(models.Model):
    ad_start = models.DateTimeField() 
    ad_end = models.DateTimeField()
    ad_duration = models.IntegerField()

@property
def get_time_diff(self):
    timediff = self.ad_end - self.ad_start
    return timediff
    #return relativedelta(self.ad_end, self.ad_start)

def save(self, *args, **kwargs):
    self.ad_duration = self.get_time_diff()
    super(Sample, self).save(*args, **kwargs)

forms.py

class SampleForm(forms.ModelForm):
class Meta:
    model = Sample
    exclude = ("submitted", 'ad_duration', "list_date" )
    widgets = {
        'ad_start': DatePickerInput(), 
        'ad_end': DatePickerInput(),
    }

Error

Django Version: 2.1.7
Exception Type: TypeError
Exception Value:'datetime.timedelta' object is not callable

score 2 · Accepted Answer · answered Mar 05 '19 at 09:28

There are two changes required in your code.

First, you need to remove @property from method get_time_diff. Because you can't call a property method via (). Or, you can still keep the property method ,but don't call it in save function, for example like this: self.ad_duration = self.get_time_diff

Second, you need to update the model field to DurationField to store the time delta object created in get_time_diff. Like this:

class Sample(models.Model):
        ad_start = models.DateTimeField() 
        ad_end = models.DateTimeField()
        ad_duration = models.DurationField()


    def get_time_diff(self):
        timediff = self.ad_end - self.ad_start
        return timediff


    def save(self, *args, **kwargs):
        self.ad_duration = self.get_time_diff()
        super(Sample, self).save(*args, **kwargs)

Or you can get the total seconds from get_time_diff and store it in ad_duration field(which will be a float field).

class Sample(models.Model):
    ad_start = models.DateTimeField() 
    ad_end = models.DateTimeField()
    ad_duration = models.FloatField()

    def get_time_diff(self):
        timediff = self.ad_end - self.ad_start
        return timediff.total_seconds()  # returns value in seconds

DurationField() has created bigint(20) type in mysql database. the stored value in database is "86400000000". And in django admin interface the value is shown as "1 00:00:00". How can i show it in admin interface as Day.(e.g. 1, 2 ) — Jhon Doe, Mar 05 '19 at 09:47
You can create a [read only method](https://docs.djangoproject.com/en/2.1/ref/contrib/admin/#django.contrib.admin.ModelAdmin.readonly_fields) in admin site, and show the day following this [answer](https://stackoverflow.com/questions/2119472/convert-a-timedelta-to-days-hours-and-minutes). — ruddra, Mar 05 '19 at 09:53

Django DateTimeField() casuing TypeError ('datetime.timedelta' object is not callable)

1 Answers1