This error is because you are concating the string and use it as domain,
As domains are must be a list of tuples or list of list

So you can make your domain like this.

domains = []

if rec.partner_id.id != False:
domains += [('partner_id', '=', rec.partner_id.id)]

if rec.account_id.id != False:
domains += [('account_id', '=', rec.account_id.id)]


Create python filter domain dinamically odoo14
https://www.odoo.com

Thanks & Regards,
Email: odoo@aktivsoftware.com
Skype: kalpeshmaheshwari

thanks but this not answer to my question.

the user have 2 field to filled: parameter_id and account_id.
if he field none of the 2 fields, my script 'ld look like :   moves = self.env['account.move.line'].search([])

if he field  parameter_id  only ->  moves = self.env['account.move.line'].search([ (' partner_id ', '=', 'self.partener_id.id') ])

if he field   account_id only ->  moves = self.env['account.move.line'].search([(' account_id ', '=', 'self.account_id.id')]) 

if he field  parameter_id and  account_id  ->  moves = self.env['account.move.line'].search([ (' account_id ', '=', 'self.account_id.id') ,(' account_id ', '=', 'self.account_id.id') ])

and then i use   'moves' for others treatements