#27263: Allow validators to short-circuit in form field validation
---------------------------------+-----------------------------------------
Reporter: Alexey Rogachev | Owner: nobody
Type: New feature | Status: new
Component: Forms | Version: master
Severity: Normal | Resolution:
Keywords: form, validator | Triage Stage: Someday/Maybe
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
---------------------------------+-----------------------------------------
Comment (by Alexey Rogachev):
Based on [https://code.djangoproject.com/ticket/27263#comment:8 idea of
Aymeric Augustin] I've come up with this workaround:
{{{#!python
class MultiValidator(object):
def __init__(self, validators):
self.validators = validators
def __call__(self, value):
for validator in self.validators:
validator(value)
}}}
Then we can group multiple validators using this `MultiValidator`:
{{{#!python
class ChartForm(forms.ModelForm):
import_file = forms.FileField(required=False, label='File for import',
validators=[MultiValidator([
FileSizeValidator(max_size='500 kb'),
FileTypeValidator(extensions=('xlsx',)),
])])
}}}
I don't like the additional nesting and mess with brackets, but besides
that I think it's OK.
We can improve the look by subclassing and creating specific class:
{{{#!python
class ChartFileMultiValidator(MultiValidator):
def __init__(self):
validators = [
FileSizeValidator(max_size='500 kb'),
FileTypeValidator(extensions=('xlsx',)),
]
super(ChartFileMultiValidator, self).__init__(validators)
}}}
Then the code reduces to:
{{{#!python
class ChartForm(forms.ModelForm):
import_file = forms.FileField(required=False, label='File for import',
validators=[ChartFileMultiValidator])
}}}
I personally prefer first approach.
In this case maybe add info about default strategy of applying validators
for form field and possible option for short circuit validation to
documentation?
--
Ticket URL: <https://code.djangoproject.com/ticket/27263#comment:11>
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