Odoo - Populate field with data

I added a product to a ticket:

class TicketExt(models.Model):
    _inherit = 'helpdesk.support'
    product = fields.Many2many('product.template',string='Product')

Now I want to display the ticket that is related to the product:

class ProductExt(models.Model):
    _inherit = 'product.template'
    p_tickets = fields.Many2many('helpdesk.support','product', string='Tickets' )

<record id="product_template_common_form_ticket_ext" model="ir.ui.view">
    <field name="name">product.template.common.form.ticket.ext</field>
    <field name="model">product.template</field>
    <field name="inherit_id" ref="product.product_template_form_view"/>
    <field name="arch" type="xml">
        <xpath expr="//page[@name='notes']" position="after">
            <page string='Tickets' >
                <field name="p_tickets"  />
            </page>
        </xpath>
    </field>
</record>

I can add new tickets to a product, but the tickets that have been added previously, do not show up.

Thank you for any suggestions

Solution

Try to add common relation field and reference fields in your definition.

product = fields.Many2many('product.template', 'product_ticket_rel', 'ticket_id', 'product_id')

and

p_ticket = fields.Many2many('helpdesk.ticket','product_ticket_rel','product_id','ticket_id')

See reference on https://www.odoo.com/documentation/14.0/reference/orm.html

And sometimes it is hard to select which one you should use product.product or product.template