Django/Python update field values (during model save)

Question

I am trying to capitalize a number of fields in my django models, when they are saved. Looking at this question, which had this answer:

class Blog(models.Model):
    name = models.CharField(max_length=100)
    def save(self):
        self.name = self.name.title()
        super(Blog, self).save()

This works fine, however, in each save, this requires some extra typing, if I want to repeat this multiple times. So I would like to create a function that takes fields as an input and re-saves them as uppercase, during the save step. So I wrote this to test it:

def save(self):
    for field in [self.first_name, self.last_name]:
        field = field.title()
    super(Artist,self).save()

However, if I had thought about it before, I would have realized that this simply overwrite the field variable. I want to cycle through a list of variables to change them. I know that some functions change the value in place, without using the =. How do they do this? Could I achieve that?

Or is there some simpler way to do what I am doing? I am going the wrong way?

SOLUTION: From the first answer, I made the function:

def cap(self, *args):
    for field in args:
        value = getattr(self, field)
        setattr(self, field, value.title())

and in my models:

def save(self):
    cap(self,'first_name', 'last_name')
    super(Artist,self).save()

Daniel Roseman · Accepted Answer · 2012-01-14 19:55:24Z

7

You can use setattr(self, my_field_name, value) to achieve this.

for field in ['first_name', 'last_name']: 
    value = getattr(self, field)
    setattr(self, field, value.title())

You won't be able to modify the value in-place as strings are immutables in Python.

edited Jan 14, 2012 at 19:55

Daniel Roseman

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answered Jan 14, 2012 at 19:23

Thomas Orozco

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