How to download text file from button on click

Question

How to download text file from button on click . I created Button in my system.xml i define frontend Model i want to download text file when i click on button .below is the code i am using

              <test_request translate="label">
                    <label></label>
                    <frontend_type>button</frontend_type>
                    <frontend_model>module/system_config_form_test</frontend_model>
                    <sort_order>17</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>0</show_in_website>
                    <show_in_store>0</show_in_store>
                </test_request>

test.php

  public function getButtonHtml()
    {
        $button = $this->getLayout()->createBlock('adminhtml/widget_button')
            ->setData(array(
                'id'        => 'kems_export',
                'label'     => $this->helper('adminhtml')->__('Export License Request'),
                'onclick'   => 'javascript:exportTest(); return false;'
            ));

        return $button->toHtml();
    }

Thanks in advance

Answer 1

Replace onclick with:

'onclick'   => 'setLocation(\''.Mage::helper('adminhtml')->getUrl('*/*/downloadTextFile') . '\')',

then in your etc/config.xml add:

<admin>
    <routers>
        <adminhtml>
            <args>
                <modules>
                    <Namespace_Modulename before="Mage_Adminhtml">Namespace_Modulename_Adminhtml</Namespace_Modulename>
                </modules>
            </args>
        </adminhtml>
    </routers>
</admin>

and finally create Namespace/Modulename/controllers/Adminhtml/System/ConfigController.php:

class Namespace_Modulename_Adminhtml_System_ConfigController extends Mage_Adminhtml_Controller_Action
{
    public function downloadTextFile()
    {
        $fileName   = 'test.txt';
        $content    = 'test content';
        $this->_prepareDownloadResponse($fileName, $content);
    }
}

I didn't test it but it should work. Of course replace Namespace_Modulename with your module name.