Module tag pair not working

Question

I'm trying to create a module tag but it just isn't working, I'm following the Hello World tutorial at Ellis Lab. My module is installed and the MCP part is working. Here is my mod file:

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Facebook_Photos {

    public $return_data = "";

    // Constructor
    public function __construct()
    {
        $this->EE =& get_instance();
        $this->return_data = 'Hello World';
        return $this->return_data;
    }

    public function get_photos()
    {
        $this->return_data = 'Hello World';
    }
}

?>

Just in case here is my tag pair in my template (it's the only template that exists):

{exp:facebook_photos:get_photos}

I’m getting the following error from EE:

The following tag cannot be processed:

{exp:facebook_photos:get_photos}

Please check that the ‘facebook_photos’ module is installed and that ‘get_photos’ is an available method of the module

Answer 1

The ‘p’ in your module’s class name must be lowercased.

From http://ellislab.com/expressionengine/user-guide/development/modules.html#the-core-module-file-mod-module-name-php:

The Core Module file is used for outputting content via Templates and doing any processing that is required by both the Control Panel and any module tags contained in a template. It includes a class with a name that matches the package (the first letter of the class name must be capitalized).

Answer 2

Ok, finally got it - took me forever but now I can hopefully help someone else that runs into this.

I checked that my mod.facebook_photos.php had the method get_photos and that everything was spelled right and it was. So I thought I'd check if it was installed, it was - but at the same time it wasn't.

If you open system/expressionengine/libraries/Template.php and go to line 1224 you find the conditional that is causing the error. There I placed some debugging information:

echo 'Class Name: ' . $class_name . '<br/>';
echo 'Tag Data Class: <br/>';
var_dump($this->tag_data[$i]['class']);
echo '<br/>Modules: <br/>';
var_dump($this->modules);
echo '<br/>Module Data Class Name: <br/>';
var_dump($this->module_data[$class_name]);

Everything came back as expected except for the last one that threw a PHP error where it couldn't find that index. So I echoed out the $class_name and I received Facebook_photos. To my surprise on line 1205 you see the following:

$class_name = ucfirst($this->tag_data[$i]['class']);

So what I did was go to my upd.facebook_photos.php and renamed every place that Facebook_Photos to Fbphotos (I removed the underscores to create a shorter namespace). I then renamed all file names and class names to match this new namespace making sure that the class names have the first letter uppercased (as that is what ucfirst) does.

Also, my tag pair had to change due to the new namespace - it now looks like this:

{exp:fbphotos:get_photos}

Now the get_photos method works as expected. Hope this helps someone else!