An example with contract_file and contract_file_name (file name depends on code of contracts throw a function for this example).

in python class :

_columns = {

'contract_file':fields.binary("Contract file (PDF)"),

'contract_file_name': fields.function(_get_contract_file_name, type="char", size=255, readonly=True, method=True),

}

contract_file_name can be a simple char field

in xml : 

<field name="contract_file" filename="contract_file_name"/> 
<field name="contract_file_name" invisible="1"/>

don't set invisible="1" if you want a field to set explicitly the file name

Hi,

Refer the following link for filename. It may help you. 
https://bugs.launchpad.net/openerp-web/+bug/1252458

Does " filters='*.xml') " work? It does not work in my odoo 14.

it raises an error your solution