Django doesn't recognise keyword blank on child of forms.Form

Question

I'm trying to create a form that will receive empty strings in some of its values. This form is not backed by a model object. I've defined it thus:

class SearchForm(forms.Form):
    device = fields.CharField(blank=True)
    min_release_date = fields.CharField(blank=True)
    price_range = fields.CharField(blank=True)
    has_in_app_purchases = fields.CharField(blank=True)

Except when I try to run a test:

def test_valid_no_data(self):
    from webanalytics.web.search import ANY_PRICE, DEFAULT_DATES, HAS_IAP_IDS
    form_data = {
        'price_range': ANY_PRICE[0],
        'min_release_date': DEFAULT_DATES[0],
        'has_in_app_purchases': HAS_IAP_IDS[0]
    }
    search = SearchForm(form_data)
    self.assertTrue(search.is_valid())

I get the following exception:

ERROR: Failure: TypeError (__init__() got an unexpected keyword argument 'blank')
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/nose/loader.py", line 411, in loadTestsFromName
    addr.filename, addr.module)
  File "/usr/local/lib/python2.7/dist-packages/nose/importer.py", line 47, in importFromPath
    return self.importFromDir(dir_path, fqname)
  File "/usr/local/lib/python2.7/dist-packages/nose/importer.py", line 94, in importFromDir
    mod = load_module(part_fqname, fh, filename, desc)
  File "/workspace/aa/tests/ci/unit/webanalytics/web/test_forms.py", line 5, in <module>
    from webanalytics.forms import SearchForm
  File "/workspace/aa/webanalytics/forms.py", line 8, in <module>
    class SearchForm(forms.Form):
  File "/workspace/aa/webanalytics/forms.py", line 15, in SearchForm
    device = fields.CharField(blank=True)
  File "/usr/local/lib/python2.7/dist-packages/django/forms/fields.py", line 187, in __init__
    super(CharField, self).__init__(*args, **kwargs)
TypeError: __init__() got an unexpected keyword argument 'blank'

According to the docs this should be ok. Am I missing something?

Answer 1

This is because Django form fields don't accept a blank parameter.

The core parameters accepted by Django form fields are:

• required

• label

• label_suffix

• initial

• widget

• help_text

• error_messages

• validators

• localize

  You can instead pass a required parameter with its value as False. So, if you pass an empty value – either None or the empty string "", the form will not raise a validation error.