Restrict django FloatField to 2 decimal places

If you are only concerned with how your FloatField appears in forms, you can use the template filter floatformat.

From the Django Docs:

If used with a numeric integer argument, floatformat rounds a number to that many decimal places.

For example, if value = 34.23234, then in your template:

{{ value|floatformat:2 }}  # outputs 34.23

If you'd like to actually ensure that your model always gets saved with only two decimal places, rather than just changing the presentation of the model in a template, a custom save method on your model will work great. The example model below shows how.

class MyDataModel(models.Model):    my_float = models.FloatField()    def save(self, *args, **kwargs):        self.my_float = round(self.my_float, 2)        super(MyDataModel, self).save(*args, **kwargs)

Now every time you save your model you will guarantee that the field will only be populated with a float of two decimal places. This can be generalized to rounding to any number of decimal places.

Since Django 1.8+ you can use a custom validator for FloatField/or any ModelFields:

def validate_decimals(value):    try:        return round(float(value), 2)    except:        raise ValidationError(            _('%(value)s is not an integer or a float  number'),            params={'value': value},        )

...and in your model you can apply it like this:

from django.db import modelsclass MyModel(models.Model):    even_field = models.FloatField(validators=[validate_decimals])