id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
27263	Allow validators to short-circuit in form field validation	Alexey Rogachev	nobody	"I have a couple of validators for files, `FileSizeValidator` and `FileTypeValidator`.

I attach it to form field like this:

{{{#!python
class ChartForm(forms.ModelForm):
    import_file = forms.FileField(required=False, label='File for import', validators = [
        FileSizeValidator(max_size='500 kb'),
        FileTypeValidator(extensions=('xlsx',))
    ])
}}}

Validators are extended from `object` and implement `__init__` and `__call__` methods (latter raises `ValidationError`).

The problem is, when I load the bigger file and with different extension, both validators execute and both error messages are shown for field (about exceeding max limit and wrong extension).

What I want - if first validator failed, don't even apply the rest of validators. For this specific scenario is not crucial, but in case of bigger amount of validators and more complex checks it can be a problem. For example if we need to read the file and verify that something exists there, why whe should do that if a size limit already exceeded.

Another option can be customizing each validator to not execute in case of existing errors.

I tried to add additional `field` argument to validator:

{{{#!python
class FileSizeValidator(object):
    def __init__(self, max_size, field):
        self.max_size = max_size
        self.field = field
}}}

and pass it in form's `__init __` method:

{{{#!python
class ChartForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(ChartForm, self).__init__(*args, **kwargs)        
        for validator in self.fields['import_file'].validators:
            validator.field = self.fields['import_file']
}}}

but I don't know how to properly call `self.field.clean()` which requires `data`. Besides that, this is not good approach, because some other validators (for example from Django core) can be attached to field.

Also this will require creating some additional mixin that must be attached along with validators.

I think there should be much simpler and elegant solution.

Can't find related questions or info in docs."	New feature	closed	Forms	dev	Normal	wontfix	form, validator		Someday/Maybe	0	0	0	0	0	0