How does Django save decimal values?

Question

What am I doing wrong?

class MyModel(models.Model):
  name = models.CharField(max_length=100, verbose_name=_("Name"), blank=False, null=False)
  rating = models.DecimalField(max_digits=2, decimal_places=2, default=0)

I do something like that:

average = count/len(votes) 
mymodel.rating = average
mymodel.save()

count is the sum of all ratings of given MyModel and votes is an array of those ratings, their division gives an average rating for MyModel (sorry if I described it incorrectly due to my poor English).

If i change previous to:

mymodel.name = 'anything'
mymodel.save()

Then 'anything' ends up in the database, but rating does not.

Why? am I using wrong field type?

Alan.

score 2 · Accepted Answer · answered Apr 05 '10 at 23:15

2

max_digits is a number of digits before and after the decimal point. With your settings it allows you to store numbers between 0.00 and 0.99. Is it right? I can not figure out the range of values for average variable.

answered Apr 05 '10 at 23:15

Yaroslav

2,718
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Yea, if ratings can be between 0 and 5, for example, then `max_digits` needs to be 3. – Mike DeSimone Apr 05 '10 at 23:22
Ok, that could be it. I will test this asap. – Odif Yltsaeb Apr 06 '10 at 07:56
That seemed to be it :). Thanks. – Odif Yltsaeb Apr 06 '10 at 16:13

score 1 · Answer 2 · answered Apr 05 '10 at 21:21

1

Models do no validation. The types you use pretty much deal with things like syncdb etc. rather than actual formatting of data, that's what a Form is for.

answered Apr 05 '10 at 21:21

Lee

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You know. Seven years is one year in dog years... https://stackoverflow.com/a/44904020/343215 – xtian Mar 09 '21 at 20:34

How does Django save decimal values?

2 Answers2