(Django) Trim whitespaces from charField


Question

How do I strip whitespaces (trim) from the end of a charField in Django?

Here is my Model, as you can see I've tried putting in clean methods but these never get run.

I've also tried doing name.strip(), models.charField().strip() but these do not work either.

Is there a way to force the charField to trim automatically for me?

Thanks.

from django.db import models
from django.forms import ModelForm
from django.core.exceptions import ValidationError
import datetime

class Employee(models.Model):
    """(Workers, Staff, etc)"""
    name                = models.CharField(blank=True, null=True, max_length=100)

    def save(self, *args, **kwargs):
        try:
            # This line doesn't do anything??
            #self.full_clean()
            Employee.clean(self)
        except ValidationError, e:
            print e.message_dict

        super(Employee, self).save(*args, **kwargs) # Real save

    # If I uncomment this, I get an TypeError: unsubscriptable object
    #def clean(self):
    #   return self.clean['name'].strip()

    def __unicode__(self):
        return self.name

    class Meta:
        verbose_name_plural = 'Employees'

    class Admin:pass


class EmployeeForm(ModelForm):
    class Meta:
        model = Employee

    # I have no idea if this method is being called or not  
    def full_clean(self):       
        return super(Employee), self.clean().strip()
        #return self.clean['name'].strip()

Edited: Updated code to my latest version. I am not sure what I am doing wrong as it's still not stripping the whitespace (trimming) the name field.

1
16
12/19/2015 10:21:57 AM

Accepted Answer

Model cleaning has to be called (it's not automatic) so place some self.full_clean() in your save method.
http://docs.djangoproject.com/en/dev/ref/models/instances/#django.db.models.Model.full_clean

As for your form, you need to return the stripped cleaned data.

return self.cleaned_data['name'].strip()

Somehow I think you just tried to do a bunch of stuff that doesn't work. Remember that forms and models are 2 very different things.

Check up on the forms docs on how to validate forms http://docs.djangoproject.com/en/dev/ref/forms/validation/

super(Employee), self.clean().strip() makes no sense at all!

Here's your code fixed:

class Employee(models.Model):
    """(Workers, Staff, etc)"""
    name = models.CharField(blank=True, null=True, max_length=100)

    def save(self, *args, **kwargs):
        self.full_clean() # performs regular validation then clean()
        super(Employee, self).save(*args, **kwargs)


    def clean(self):
        """
        Custom validation (read docs)
        PS: why do you have null=True on charfield? 
        we could avoid the check for name
        """
        if self.name: 
            self.name = self.name.strip()


class EmployeeForm(ModelForm):
    class Meta:
        model = Employee


    def clean_name(self):
        """
        If somebody enters into this form ' hello ', 
        the extra whitespace will be stripped.
        """
        return self.cleaned_data.get('name', '').strip()
11
2/18/2011 6:38:33 PM

When you're using a ModelForm instance to create/edit a model, the model's clean() method is guaranteed to be called. So, if you want to strip whitespace from a field, you just add a clean() method to your model (no need to edit the ModelForm class):

class Employee(models.Model):
    """(Workers, Staff, etc)"""
    name = models.CharField(blank=True, null=True, max_length=100)

    def clean(self):
        if self.name:
            self.name = self.name.strip()

I find the following code snippet useful- it trims the whitespace for all of the model's fields which subclass either CharField or TextField (so this also catches URLField fields) without needing to specify the fields individually:

def clean(self):
    for field in self._meta.fields:
        if isinstance(field, (models.CharField, models.TextField)):
            value = getattr(self, field.name)
            if value:
                setattr(self, field.name, value.strip())

Someone correctly pointed out that you should not be using null=True in the name declaration. Best practice is to avoid null=True for string fields, in which case the above simplifies to:

def clean(self):
    for field in self._meta.fields:
        if isinstance(field, (models.CharField, models.TextField)):
            setattr(self, field.name, getattr(self, field.name).strip())

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