Running a query within a class method

Question

So i'm looking at http://ellislab.com/expressionengine/user-guide/development/usage/database.html

I've used

$query = $this->EE->db->query("SELECT channel_name FROM exp_channels");

many times, but never within a class. and using $this-> causes issues. I'm no expert but how do i overcome this?

class Name
{
    public $variable;

    public function Something()
    {
         if($this->variable == "whatever")
           {
                //Run query to pull data based on $variable
                // This causes errors. I assume because $this is now something else.
                $this->EE->db->query("SELECT * FROM tablename WHERE...");
           }
    }
}

Message: Undefined property: Module::$EE

Message: Trying to get property of non-object

Fatal error: Call to a member function query() on a non-object

Answer 1

You first need to initialize global object like:

$this->EE =& get_instance();