FileTypeValidator

validators.py

import re
from django.core.exceptions import ValidationError
from django.utils.translation import ugettext_lazy as _


class FileTypeValidator(object):
    error_message = _(u'Please upload a file of the correct type.')

    def __init__(self, regex, error_message=None):
        self.regex = re.compile(regex)
        if self.error_message is not None:
            self.error_message = error_message

    def __call__(self, value):
        import magic
        try:
            if not hasattr(value, 'read'):
                raise ValidationError(self.error_message)
            filetype = magic.from_buffer(value.read())
            if not self.regex.match(filetype):
                raise ValidationError(self.error_message)
        finally:
            if hasattr(value, 'seek'):
                value.seek(0)


pdf_validator = FileTypeValidator(r'^PDF document.*$',
    error_message=_(u'Bitte laden Sie eine PDF Datei hoch.'))