Adding onchange user interface logic
It is possible to make changes to the web client view while the user is editing it. This mechanism is known as onchange. It is implemented through methods decorated with @api.onchange, and they are triggered by the user interface view when the user edits a value on a particular field.
Since Odoo 13, the same effect can be achieved by using a particular form of computed fields, called computed writable fields. This ORM improvement aims to avoid some limitations of the classic onchange mechanism, and in the long run, it should replace it completely.
Classic onchange methods
Onchange methods can change other field values in the form, perform a validation, show a message to the user, or set a domain filter in relation fields, limiting the available options.
The onchange method is called asynchronously and returns data that's being used by the web client to update the fields in the current view.
Onchange methods are linked to the...
