Hi,

Because you need either give @api.one or use a for loop to iterate in the recordset. Try like this:

from openerp import models, fields, api

class stock_inherited(models.Model):

    _inherit = 'stock.pack.operation'
    
    @api.depends('picking_id.partner_id')
    def _compute_child_contact_ids(self):
        for record in self:
            partner_id = record.picking_id.partner_id.id
            is_company = record.picking_id.partner_id.is_company
            parent_id = record.picking_id.partner_id.parent_id
            record.filters = is_company +','+parent_id+','+partner_id
        

    

    partner_id = fields.Many2one(string="Partner ID", related='picking_id.partner_id')
    filters = fields.Char(compute="_compute_child_contact_ids", string="Filters")

I don't understand the way you need partner_id and parent_id, you need exactly the name or record id? Please tell what you exactly need in filters.