(Django) Trim whitespaces from charField
Solution 1
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()
Solution 2
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())
Solution 3
Django 1.9 offers a simple way of accomplishing this. By using the strip
argument whose default is True, you can make sure that leading and trailing whitespace is trimmed. You can only do that in form fields though in order to make sure that user input is trimmed. But that still won't protect the model itself. If you still want to do that, you can use any of the methods above.
For more information, visit https://docs.djangoproject.com/en/1.9/ref/forms/fields/#charfield
Solution 4
If you have so many data-fields to be trimmed, why not try extending CharField?
from django.db import models
from django.utils.translation import ugettext_lazy as _
class TrimCharField(models.CharField):
description = _(
"CharField that ignores leading"
" and trailing spaces in data")
def get_prep_value(self, value)
return trim(super(TrimCharField, self
).get_prep_value(value))
def pre_save(self, model_instance, add):
return trim(super(TrimCharField, self
).pre_save(model_instance, add))
UPDATE: For Django versions <= 1.7 if you want to extend field, you are to use models.SubfieldBase metaclass. So here it will be like:
class TrimCharField(six.with_metaclass(
models.SubfieldBase, models.CharField)):
Solution 5
I'm handling this in views as a decorator. I'm also truncating field values that exceed a CharField max_length value.
from django import forms
from django import models
from django.db.models.fields import FieldDoesNotExist
from django.utils.encoding import smart_str
class CleanCharField(forms.CharField):
"""Django's default form handling drives me nuts wrt trailing
spaces. http://code.djangoproject.com/attachment/ticket/6362
"""
def clean(self, value):
if value is None:
value = u''
value = smart_str(value).strip()
value = super(forms.CharField, self).clean(value)
return value
def truncate_charfield(model):
"""decorator to truncate CharField data to model field max_length.
Apply to the clean method in views Form:
@truncate_charfield(MyModel)
def clean(self):
...
"""
def wrap(f):
def wrapped_f(*args):
f(*args)
d = args[0].cleaned_data
for field in model._meta.fields:
try:
mf = model._meta.get_field(field.name)
if isinstance(mf, models.CharField) and field.name in d:
d[field.name] = d[field.name][:mf.max_length]
except FieldDoesNotExist:
pass
return d
return wrapped_f
return wrap
zardon
Updated on July 28, 2022Comments
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zardon almost 2 years
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.
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zardon over 13 yearsI am still having problems -- it is still not stripping the whitespace (trim). I tried following the tutorial you posted, and your idea of calling full_clean() in the save method. I am struggling to understand a) Is the EmployeeForm being called? b) Is the full_clean() method being called? I have updated my code sample in my question. I am hopeful that I can get pointed in the right direction.
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zardon over 13 yearsThanks for your help, I'm pretty new to Django/Python; so apologies for the various mistakes and misunderstandings of how I should be implementing various features.
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Yuji 'Tomita' Tomita over 13 yearsNo problem. Just consult the docs instead of guessing and you'll figure it all out! The Django docs are godlike in clarity and examples.
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zardon over 13 yearsThat worked great. With regards to your comment about why the name field was accepting null=True, its because I'm just starting out with Django and am not too familiar with everything. Thanks anyway though as this solved my problem. I can, hopefully, now roll it out to all textfields in the future.
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Yuji 'Tomita' Tomita over 13 years
null=True
means the database can store anull
value which is important for fields like an optionalInteger
field because''
would be invalid. For character fields,''
is often completely acceptable as a blank value, which also ensures that the field would always return a string, so you could safely do any python string operations on it likestrip()
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zardon over 13 yearsThanks, but seems a bit too advanced for me -- I am not sure where I would put this file, how I would call it, etc; but as I pick up Django/Python I'm sure I'll pick all this up along the way. Thanks again.
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Jeff Bauer over 13 yearszardon, you could simply put it in a module, say maxtruncate.py then import into your views.py: from maxtruncate import CleanCharField, truncate_charfield. Then replace CharField with CleanCharField and place the truncate_charfield decorator at the top of your clean method. The main advantage is you won't have your input field exceed your max_length ... which will cause a nasty runtime error from your database.
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Troy Grosfield over 10 yearsGood solution. However, the one thing I would change is: if value and hasattr(value, 'strip'): As some custom fields don't contain a strip method for a value (at least is my case). This protects against that.
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lapin over 4 yearsI need to double down on this comment for future ppl that stumble upon this: after Django
1.9
, even when you useModelForm
, the underneathcharField
will havestrip
toTrue
by default. Which means you don't need to manually stipe anything. However, please note that depending on how you implemented the view, you may still see untrimmed fields because on theform
object you return to the view it is still untrimmed. -
Hunger over 2 yearsAfter 1.9, strip is enable by default. If you want to disable this feature, check my answer: stackoverflow.com/a/68112671/2251785