===============
on_before_apply
===============

on_before_apply(item, params)

**domain**: client 

**language**: javascript

**class** :doc:`Item class </refs/client/item_api>`

Description
===========

Occurs before an application saves dataset changes to the project 
database.

The ``item`` parameter is an item that triggered the event.

The ``params`` parameter is an object that has been passed to the
:doc:`apply <m_apply>`
method or an empty object if this object is undefined. 
This object is passed to the server and can be used in the 
:doc:`on_apply </refs/server/item/on_apply>` 
event handler to perform some actions when saving changes to the database. 

Write an on_before_apply event handler to take specific action immediately before 
an application saves the change log to the project database.

``on_before_apply`` is triggered by 
:doc:`apply <m_apply>`
method.

See also
========

:doc:`Modifying datasets </programming/data/modifying_datasets>`
