Using Odoo 13 Community Edition on Windows.

I'm trying to learn how onchange works.

I want to change a many2one field (id) when the user chooses a specefic value from a selection field.

I have the selection field:

vorgang_auswahl = fields.Selection([

        ('gewinde', 'Gewinde schneiden'),

        ('senken', 'Senken'),

        ('kanten', 'Kanten'),

        ('mikro', 'Mikroecken entfernen'),

        ('schweissen', 'Schweißen'),

        ('schleifen', 'Schleifen')],

        string="Operations", default="gewinde")

So if the user choose the value "gewinde" the field "workcenter_id" should change to a specefic workcenter.

I'm doing this in the "mrp_routing.py".

I tried to get an answer from other questions but still i dont get it.

The base is something like:

    @api.onchange('vorgang_auswahl')

    def _onchange_vorgang_auswahl(self):

        if (((self.vorgang auswahl = 'gewinde')))

        self.workcenter_id = ((('6')))