Add a custom button to a core backend component

Question

Is it possible to add a custom button (with a custom action, of course) to the JToolbar of a standard Joomla 3 component (com_contents) without modifying the original source code?

Background: I need to add a button to the com_contents main screen (the list of all the articles) to create a massive mail function. I can, of course, modify the standard Joomla files, but if I modify it, when I upgrade Joomla to a new version I'll lose my customization. But, if somehow I can add the button, I won't lose any change when updating...

And if it's possible to do this, how can it be done? Creating a plugin? Is there any tutorial to guide me thru the creation of this addon?

Answer 1

Here is a draft idea using a plugin:

You need to create a system plugin (I am not getting into that) and to use the event onBeforeRender. Inside you get an instance of your Toolbar and append the button.

class PlgSystemCustomtoolbar extends JPlugin
{
    public function onBeforeRender()
    {
        // Get the application object
        $app = JFactory::getApplication();

        // Run in backend
        if ($app->isAdmin() === true)
        {
            // Get the input object
            $input = $app->input;

            // Append button just on Articles
            if ($input->getCmd('option') === 'com_content' && $input->getCmd('view', 'articles') === 'articles')
            {
                // Get an instance of the Toolbar
                $toolbar = JToolbar::getInstance('toolbar');

                // Add your custom button here
                $url = JRoute::_('index.php?option=com_example&task=massemail&format=raw');
                $toolbar->appendButton('Link', 'export', 'Mass Email', $url);
            }
        }
    }
}

Answer 2

Working in an external way, you can create an Administrator module, an editors-xtd plug-in, or a system plugin. In both cases, when your code is executed, you can add some Javascript code to inject the button in the required location.

• Administrator module, it is going to be shown in a position, for instance menu. It can add anything to all pages.
• editors-xtd plug-in, it is going to be shown only as a button under the text editor. It can open a full view from your component.
• system plugin, it can do anything, but it does not have an User Interface by itself, like the previous cases.