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How to make a Django model fields calculated at runtime?


How to make a Django model fields calculated at runtime?

By : Dharanay
Date : November 20 2020, 07:00 PM
this will help you're going about it in a strange way. you only need to store the birthday (which you're already doing).
if you need to do queries based on age, take in the age, and then search on the birthdays that fit the requirements.
code :


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django - weird results (cached?) obtained while storing calculated values in fields at model level

django - weird results (cached?) obtained while storing calculated values in fields at model level


By : user3476818
Date : March 29 2020, 07:55 AM
I wish this help you Without seeing the code you are using to invoke all these calculations, I can only guess what the problem might be. It may be helpful to show your view code (or other), which 'kicks off' the calculations of subtotal.
There are two potential issues I can see here.
code :
def counter(self):
    output = 0
    if self.kids.count() == 0:
        if self.price == None or self.amount == None:
            output = 0
        else:
            output = self.price * self.amount
    else:
        output = self.kids.aggregate(Sum('subtotal'))['subtotal__sum']
    self.subtotal = output
    self.save() # save the calculation
def save(self, *args, **kwargs):
    self.counter() # calculate subtotal
    super(Element, self).save(*args, **kwargs) # Call the "real" save() method.
    for parent in self.element_set.all(): # use a related name instead
        parent.save() # force recalculation of each parent
How can I make my model fields optional in Django?

How can I make my model fields optional in Django?


By : JAYCHI
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further I'm trying to follow the full example at the bottom of , You would have to add blank=True as well in field definition.
code :
date_of_birth = models.DateField(null=True, blank=True)
Django Model field calculated from other fields

Django Model field calculated from other fields


By : user3752407
Date : March 29 2020, 07:55 AM
Hope that helps Figured it out (w the help of AbhiP!) Python int typecasting was the main culprit. Stupid problem to have!
Below is what worked, and allowed me to not save the calculated field (but display it and make it act like a field in the model):
code :
@property
    def yield_num(self):
        if self.starts > 0:
              #needed the float() to cast it out of an int
             return self.finishes / float(self.starts)
        else:
             return 0
How to make a Django fixture for a model with no fields?

How to make a Django fixture for a model with no fields?


By : user3443878
Date : March 29 2020, 07:55 AM
it fixes the issue YAML works pretty much the same way as JSON does, so we can simply specify fields to be an empty dictionary:
code :
# sample.yaml

- model: app.Model
  pk: 1
  fields: {}
Mvc 3: Using calculated fields in a model and displaying calculated fields in a view

Mvc 3: Using calculated fields in a model and displaying calculated fields in a view


By : Mira M
Date : March 29 2020, 07:55 AM
around this issue I need to show the result of a stored procedure and make it look like the attached image. I know I have to create a model that will look like this , The proper way would be to create a ViewModel:
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