Simple Observer not working

Question

I'm new to Magento and I'm trying to add an additional button to a pre-existing admin form using an observer. I set up my config to what I believe is the right event handle. I created an observer and added the name and method to config. I don't believe my observer is ever hit since Mage log is not printing. Can anyone see where I'm going wrong?

Sales.xml - (Enterprise layout file)

<layout>
   <adminhtml_sales_order_view>
        <reference name="content">
            <block type="adminhtml/sales_order_view" name="sales_order_edit"></block>
        </reference>
   </adminhtml_sales_order_view>
</layout>

config.xml

<?xml version="1.0" encoding="UTF-8"?>

<config>
    <modules>
        <Mycompany_MyModule>
            <version>0.1.0</version>
        </Mycompany_MyModule>
    </modules>
    <global>
        <events>
            <adminhtml_sales_order_view>
                <observers>
                    <my_observer>
                        <type>singleton</type>
                        <class>Mycompany_MyModule_Model_Observer</class>
                        <method>addMyButton</method>
                    </my_observer>
                </observers>
            </adminhtml_sales_order_view>
        </events>
    </global>
</config>

Observer.php

<?php

class Mycompany_MyModule_Model_Observer
{
    public function addMyButton($observer)
    {
        Mage::log('test observer');

        $container = $observer->getBlock();
        if(null !== $container && $container->getType() == 'adminhtml/sales_order_view')
        {
            $data = array(
                'label'     => 'My button',
                'class'     => 'go',
                'onclick'   => 'setLocation(\' '  . Mage::getUrl('*/*', array('param' => 'value')) . '\')',
            );
            $container->addButton('my_button_identifier', $data);
        }
        return $this;
    }
}

Answer 1

You need to extend layout instead of writing observer. You cannot dispatch a new event using layout files. Please check more on how to extend layout handles

Answer 2

There is no event with the name <adminhtml_sales_order_view>, it is a layout handle.
You need to use event like <core_block_abstract_prepare_layout_before> as below :

<adminhtml>
        <events>
            <core_block_abstract_prepare_layout_before>
                <observers>
                    .....
                </observers>
            </core_block_abstract_prepare_layout_before>
        </events>
    </adminhtml> 

Reference Links :

• http://inchoo.net/category/magento/events-observers/

• https://www.nicksays.co.uk/magento-events-cheat-sheet-1-9/

• Magento add new Button on Sales order view

Answer 3

FINAL CODE - I did a layout update and it worked for me.

config.xml

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <MyCompany_MyModule>
            <version>0.1.0</version>
        </MyCompany_MyModule>
    </modules>
 <adminhtml>
     <layout>
          <updates>
               <myupdate>
                     <file>myupdate.xml</file>
               </myupdate>
          </updates>
     </layout>
 </adminhtml>
</config>

myupdate.xml

<layout version="0.1.0">
    <adminhtml_sales_order_view>
        <reference name="sales_order_edit">
            <action method="addButton">
                <id>my_button_identifier</id>
                <data>
                    <label>My button</label>
                    <class>go</class>
                </data>
            </action>
        </reference>
    </adminhtml_sales_order_view>
</layout>

Answer 4

Have you defined your <blocks> and <models> within config.xml? If you didnt define models, that will explain why your observer didn't work. Well, that, and the fact that you have a layout handle as your event.

Additionally, instead of

if(null !== $container && $container->getType() == 'adminhtml/sales_order_view')

you should go with

if($container instanceof Mage_Adminhtml_Block_Sales_Order_View)

That's because if you have some module or customization in the future, the "type" may change but it will most likely still extend from the original class.

Additionally, a super helpful tool created by Alan Storm, Commerce Bug. I use it every single day. In fact, it will provide you with a list of available observer events available on a given page.

Also, xdebug is very helpful when debugging Magento. You will know right away if your observer is firing. I made a short video on how to install xdebug. Xdebug Installation