I'm with the same problem and don't find a solution as simple as the one you mention. But there is a solution as i think simple enough : use the api.constrains. Here is my modus operandi:
1) I save the file's name
files = fields.Binary(string="Download Zip") filename = fields.Char()
<field name="filename" invisible="1" /> <field name="files" filename="filename" />
2) I use the api.constrains to verify the extension
@api.one @api.constrains('filename') def _check_filename(self): if self.files: if not self.filename: raise exceptions.ValidationError(_("There is no file")) else: # Check the file's extension tmp = self.filename.split('.') ext = tmp[len(tmp)-1] if ext != 'zip': raise exceptions.ValidationError(_("The file must be a zip file"))
I know, it's not a very beautiful way to do it but it's an alternative solution to your problem.
Hope that help you.