I am using Odoo 17.

I have created a custom module that opens the mail composer in the "helpdesk.ticket" model extended whenever i click the "Send message" button in the chatter. I have also made it so that when the composer is opened it automatically selects a custom mail template i created within Odoo.

When i click "Send message" it instantly opens the composer in extended mode.

You can see here that the composer opens with a template already set.

This is the model and code that sets the template:
Model: "helpdesk_default_mail_template/models/mail_compose_message.py"
code:

from odoo import models, api

class MailComposeMessage(models.TransientModel):
    _inherit = "mail.compose.message"

    @api.model
    def default_get(self, fields_list):
        res = super().default_get(fields_list)
        if res.get("model") == "helpdesk.ticket" and res.get("subtype_id") == 1:
            template = self.env["mail.template"].search(
                [("name", "=", "Helpdesk Default Mail Template")], limit=1
            )
            if template:
                res["template_id"] = template.id
        return res

 
The only problem i have is that the recipient and body fields are not set with values from the template. I have to open "Load template" and manually select the "Helpdesk Default Mail Template" again, before it sets the recipients and renders the body_html from the template to the body inside the composer.

This is when the composer has just been opened:


And this is after i have manually selected the "Helpdesk Default Mail Template" again:

You can see that the recipients has been set and the body content has been set.

How do i make sure that these two fields are set automatically when the composer is opened just like the template is automatically set when the composer is opened.