======================================
JavaScript customizations in the admin
======================================

.. _admin-javascript-inline-form-events:

Inline form events
==================

You may want to execute some JavaScript when an inline form is added or removed
in the admin change form. The ``formset:added`` and ``formset:removed`` jQuery
events allow this. The event handler is passed three arguments:

* ``event`` is the ``jQuery`` event.
* ``$row`` is the newly added (or removed) row.
* ``formsetName`` is the formset the row belongs to.

The event is fired using the :ref:`django.jQuery namespace
<contrib-admin-jquery>`.

In your custom ``change_form.html`` template, extend the
``admin_change_form_document_ready`` block and add the event listener code:

.. code-block:: html+django

    {% extends 'admin/change_form.html' %}
    {% load static %}

    {% block admin_change_form_document_ready %}
    {{ block.super }}
    <script src="{% static 'app/formset_handlers.js' %}"></script>
    {% endblock %}

.. code-block:: javascript
    :caption: ``app/static/app/formset_handlers.js``

    (function($) {
        $(document).on('formset:added', function(event, $row, formsetName) {
            if (formsetName == 'author_set') {
                // Do something
            }
        });

        $(document).on('formset:removed', function(event, $row, formsetName) {
            // Row removed
        });
    })(django.jQuery);

Two points to keep in mind:

* The JavaScript code must go in a template block if you are inheriting
  ``admin/change_form.html`` or it won't be rendered in the final HTML.
* ``{{ block.super }}`` is added because Django's
  ``admin_change_form_document_ready`` block contains JavaScript code to handle
  various operations in the change form and we need that to be rendered too.

Sometimes you'll need to work with ``jQuery`` plugins that are not registered
in the ``django.jQuery`` namespace. To do that, change how the code listens for
events. Instead of wrapping the listener in the ``django.jQuery`` namespace,
listen to the event triggered from there. For example:

.. code-block:: html+django

    {% extends 'admin/change_form.html' %}
    {% load static %}

    {% block admin_change_form_document_ready %}
    {{ block.super }}
    <script src="{% static 'app/unregistered_handlers.js' %}"></script>
    {% endblock %}

.. code-block:: javascript
    :caption: ``app/static/app/unregistered_handlers.js``

    django.jQuery(document).on('formset:added', function(event, $row, formsetName) {
        // Row added
    });

    django.jQuery(document).on('formset:removed', function(event, $row, formsetName) {
        // Row removed
    });
