Hi,

The issue is that clicking a row in a tree view redirects to the form view of that same model. If your tree is built on a custom SQL view/model, Odoo looks for a form view on that model; which doesn't exist, so nothing happens.

To redirect to the form view of the main model (the one the Many2one points to), you have two options:

Option 1; Add open_rec method on the SQL model:

def open_record(self):
    return {
        'type': 'ir.actions.act_window',
        'res_model': 'your.main.model',
        'view_mode': 'form',
        'res_id': self.main_model_id.id,
        'target': 'current',
    }

Then add a button in the tree view that calls it.

Option 2; Use optional Many2one column with built-in redirect:

In your tree view XML, make the Many2one field clickable by ensuring it's a proper many2one widget; clicking it natively opens the related record's form view:

<field name="main_model_id" />

Clicking the Many2one value in the list will open the linked record's form directly; no extra code needed.

Option 2 is the simplest if you just need the user to navigate to the related record.