contenttyperestrictedfilefield.py

#http://bixly.com/blog/accept-only-specific-file-types-in-django-file-upload/
from django.db.models import FileField
from django.forms import forms
from django.template.defaultfilters import filesizeformat
from django.utils.translation import ugettext_lazy as _

class ContentTypeRestrictedFileField(FileField):
    """
    Same as FileField, but you can specify:
        * content_types - list containing allowed content_types.
        Example: ['application/pdf', 'image/jpeg']
        * max_upload_size - a number indicating the maximum file
        size allowed for upload.
            2.5MB - 2621440
            5MB - 5242880
            10MB - 10485760
            20MB - 20971520
            50MB - 5242880
            100MB 104857600
            250MB - 214958080
            500MB - 429916160
    """
    def __init__(self,  content_types=[], max_upload_size=429916160, **kwargs):
        self.content_types = content_types
        self.max_upload_size = max_upload_size

        super(ContentTypeRestrictedFileField, self).__init__(**kwargs)

    def clean(self, *args, **kwargs):
        data = super(ContentTypeRestrictedFileField, self).clean(*args, **kwargs)
        file = data.file
        try:
            content_type = file.content_type
            if self.content_types == [] or content_type in self.content_types:
                if file.size > self.max_upload_size:
                    raise forms.ValidationError(_('Please keep filesize under %s. Current filesize %s')
                                                % (filesizeformat(self.max_upload_size), filesizeformat(file._size)))
            else:
                raise forms.ValidationError(_('Filetype %s not supported.'%content_type))
        except AttributeError:
            pass

        return data