Saving previous date and adding new date in Django - django

Question

I have been working on an application where user adds his tasks which he is supposed to perform, once the task is added he can update the progress.
In my model I have a date field, where user is supposed to enter the estimated completion date.
My task model
"""Creating KRA Based on Institutional Objectives"""
class KraBasedOnIo(models.Model):
io = models.ForeignKey(InstitutionalObjectives, on_delete=models.CASCADE, related_name='kra_io')
kra_title = models.CharField(max_length = 200)
kra_description = models.TextField()
kra_target = models.CharField(max_length=200)
kra_added_date = models.DateTimeField(auto_now_add=True)
estimated_date = models.????
While updating the progress, if the user wants to extend his timeline, I am looking for an option where I can save his current estimated completion date and add the new date also.
And when I am displaying his progress I want to show his defined completion date and also the extended completion date in the template.
I have tried a work around with model.JSONField() but couldn't reach there.
There is no ListField or DictionaryField so what could be a better solution for this?

Answer 1

So I would use the library django-simple-history to keep track of the different updates of this field.
"""Creating KRA Based on Institutional Objectives"""
class KraBasedOnIo(models.Model):
io = models.ForeignKey(InstitutionalObjectives, on_delete=models.CASCADE, related_name='kra_io')
kra_title = models.CharField(max_length = 200)
kra_description = models.TextField()
kra_target = models.CharField(max_length=200)
kra_added_date = models.DateTimeField(auto_now_add=True)
estimated_date = models.DateTimeField(default=timezone.now)
history = HistoricalRecords()
Then in you view, you can see the different version by doing :
for record in kra_based_on_info.history.all():
print(record)

Answer 2

Keep it simple and create two separated fields:
class KraBasedOnIo(models.Model):
# ...
estimated_completion_date = models.DateTimeField(null=True, blank=True)
extended_completion_date = models.DateTimeField(null=True, blank=True)
If you need to keep track of all the completion date changes, I suggest you to create a new model
class CompletionDate(models.Model):
# ...
kra = models.ForeignKey(KraBasedOnIo, related_name='completion_dates', on_delete=models.CASCADE)
estimated_date = models.DateTimeField(auto_now_add=True)
And then get the last completion date for a KraBasedOnIo instance like this:
my_last_completion_date = KraBasedOnIo.completion_dates.last()