Executing Code On Doctype Events

To execute code when a DocType is inserted, validated (before saving), updated, submitted, cancelled, deleted, you must write in the DocType's controller module.

1. Controller Module

The controller module exists in the doctype folder in the Module of the DocType. For example, the controller for ToDo exists in frappe/desk/doctype/todo/todo.py (version 5). A controller template is created when the DocType is created. which looks like

from __future__ import unicode_literals

import frappe
from frappe.model.document import Document

class CustomType(Document):
    pass

2. Document Properties

All the fields and child tables are available to the class as attributes. For example the name property is self.name

3. Adding Methods

In this module, you can add standard methods to the class that are called when a document of that type is created. Standard Handlers are:

1. autoname: Called while naming. You can set the self.name property in the method.
2. before_insert: Called before a document is inserted.
3. validate: Called before document is saved. You can throw an exception if you don't want the document to be saved
4. on_update: Called after the document is inserted or updated in the database.
5. on_submit: Called after submission.
6. on_cancel: Called after cancellation.
7. on_trash: Called after document is deleted.