'The official MIME type for this document
@return: \'application/xxx\' for this file'

@property
def mimeType(self):

    if self.mime_type:
        return self.mime_type
    for (pattern, mime_type) in self._extpattern_to_mime.items():
        if fnmatch.fnmatch(self.filename, pattern):
            return mime_type
