proper_multivaluefield.py

from django.core import validators
from django.forms import MultiValueField
from django.forms.util import ErrorList
from django.core.exceptions import ValidationError

class ProperMultiValueField(MultiValueField):
    """django.forms.fields.MultiValueField with a validation fix

    If a MultiValueField is ``required=True``, it should still be
    valid even if one or more of the sub-fields are empty. In Django
    (from newforms-admin until at least 1.1) this is not the case: any
    empty sub-field causes a validation error for the whole
    multi-value field. This class fixes this behavior.

    To get the Django stock MultiValueField behavior with this class,
    declare all sub-fields as ``required=True``.
    """
    def clean(self, value):
        """
        Validates every value in the given list. A value is validated against
        the corresponding Field in self.fields.

        For example, if this MultiValueField was instantiated with
        fields=(DateField(), TimeField()), clean() would call
        DateField.clean(value[0]) and TimeField.clean(value[1]).
        """
        clean_data = []
        errors = ErrorList()
        if not value or isinstance(value, (list, tuple)):
            if not value or not [v for v in value if v not in validators.EMPTY_VALUES]:
                if self.required:
                    raise ValidationError(self.error_messages['required'])
                else:
                    return self.compress([])
        else:
            raise ValidationError(self.error_messages['invalid'])
        for i, field in enumerate(self.fields):
            try:
                field_value = value[i]
            except IndexError:
                field_value = None
            # The only change to MultiValueField is here:
            # ``self.required`` was changed to ``field.required``
            if field.required and field_value in validators.EMPTY_VALUES:
                raise ValidationError(self.error_messages['required'])
            try:
                clean_data.append(field.clean(field_value))
            except ValidationError, e:
                errors.extend(e.messages)
        if errors:
            raise ValidationError(errors)

        out = self.compress(clean_data)
        self.validate(out)
        return out