Hello,

I'm getting a singleton error in if-else condition and would like to add for loop to run code smoothly. The error is arising at 

'partner_id': rec.partner_ids.id,

in which partner_ids is many2many. The action code is as below

def action_create_purchase_order(self):
    """create purchase order and internal transfer"""
    for rec in self.requisition_order_ids:
        if rec.requisition_type == 'internal_transfer':
            self.env['stock.picking'].create({
                'location_id': self.source_location_id.id,
                'location_dest_id': self.destination_location_id.id,
                'picking_type_id': self.internal_picking_id.id,
                'requisition_order': self.name,
                'move_ids_without_package': [(0, 0, {
                    'name': rec.product_id.name,
                    'product_id': rec.product_id.id,
                    'product_uom': rec.product_id.uom_id,
                    'product_uom_qty': rec.quantity,
                    'location_id': self.source_location_id.id,
                    'location_dest_id': self.destination_location_id.id,
                })]
            })
        else:
            self.env['purchase.order'].create({
                'partner_id': rec.partner_ids.id,
                'requisition_order': self.name,
                'project_requisition_name': self.project_requisition_name_id.name,
                'job_number': self.job_num,
                "order_line": [(0, 0, {
                    'product_id': rec.product_id.id,
                    'product_qty': rec.quantity,
                    'name': rec.description,
                })]})
    self.write({'state': 'purchase_order_created'})

Thank you in advance.