Magento: add button on order view page with custom module

Question

I want to add a button on the Order View page of the Admin.

I created a custom module in app\code\community\CPT\TCS and added subfolders Block, controllers, etc, Helper, Model, sql

This is my CPT_TCS.xml file in app\etc\modules\

CPT_TCS.xml:

<?xml version="1.0"?>
<config>
     <modules>
        <CPT_TCS>
            <active>true</active>
            <codePool>community</codePool>
            <depends>
                <Mage_Adminhtml />
            </depends> 
        </CPT_TCS>
     </modules>
</config>

This is my custom module's etc\config.xml:

<?xml version="1.0" ?>
<config>
  <modules>
    <CPT_TCS>
      <version>
        1.0.0
      </version>
    </CPT_TCS>
  </modules>

  <blocks>
    <cpttcs>
      <class>CPT_TCS_Block</class>
    </cpttcs>
    <adminhtml>
      <rewrite>
        <sales_order_view>CPT_TCS_Block_Adminhtml_Sales_Order_View</sales_order_view>
      </rewrite>
    </adminhtml>
  </blocks>
</config>

Now I've added view.php in TCS\Block\Adminhtml\Sales\Order\

<?php
class CPT_TCS_Block_Sales_Order_View extends Mage_Adminhtml_Block_Adminhtml_Sales_Order_View
{

    public function __construct() {

        //parent constructor
        parent::__construct();

        //create URL to our custom action
        $url = Mage::helper("adminhtml")->getUrl(
            "CPT_TCS/order/doSomething",
            array('order_id'=>$this->getOrder()->getId())
        );

        //add the button
        $this->_addButton('cygtest_resubmit', array(
                'label'     => Mage::helper('sales')->__('Send TCS'),
                'onclick'   => 'setLocation(\'' . $url . '\')',
                'class'     => 'go'
        ));

    }

}

The "Send TCS" button is not showing on order view page (this "Send TCS" button should ultimately send data order data on web service).

What can be wrong here?

Answer 1

I think your problem is that the <blocks> tag from your config.xml is not in the right place.
It should be a child of the node <global>

So make your config.xml look like this:

<?xml version="1.0" ?>
<config>
  <modules>
    <CPT_TCS>
      <version>
        1.0.0
      </version>
    </CPT_TCS>
  </modules>
  <global>
  <blocks>
    <cpttcs>
      <class>CPT_TCS_Block</class>
    </cpttcs>
    <adminhtml>
      <rewrite>
        <sales_order_view>CPT_TCS_Block_Adminhtml_Sales_Order_View</sales_order_view>
      </rewrite>
    </adminhtml>
  </blocks>
  </global>
</config>

Alternative
You don't need to rewrite the order view block to add a button. you can do it cleaner with an observer.
Add this in the config.xml of your module under the config root note.

<adminhtml>
    <events>
        <controller_action_layout_render_before_adminhtml_sales_order_view>
            <observers>
                <ctp_tcs>
                    <class>ctptcs/adminhtml_observer</class>
                    <method>addTcsButton</method>
                </ctp_tcs>
            </observers>
        </controller_action_layout_render_before_adminhtml_sales_order_view>
    </events>
</adminhtml>

Then declare your models in the same config.xml.
Under the <global> tag add this:

<models>
    <cpttcs>
        <class>CPT_TCS_Model</class>
    </cpttcs>
</models>

Then create the observer class CTP/TCS/Model/Adminhtml/Observer.php

<?php 
class CTP_TCS_Model_Adminhtml_Observer 
{
    public function addTcsButton($observer) {
        $block = Mage::app()->getLayout()->getBlock('sales_order_edit');
        if (!$block){
            return $this;
        }
        $order = Mage::registry('current_order');
        $url = Mage::helper("adminhtml")->getUrl(
            "CPT_TCS/order/doSomething",
            array('order_id'=>$order->getId())
        );
        $block->addButton('cygtest_resubmit', array(
                'label'     => Mage::helper('sales')->__('Send TCS'),
                'onclick'   => 'setLocation(\'' . $url . '\')',
                'class'     => 'go'
        ));
        return $this;
    }
}