How to use add_action('wp_ajax_[action name]',...) for a specific page with condition?

Question

In my plugin, I'm using wp_ajax, This hook does not work when I wrap the init function call with a condition like this :

public function __construct(){
   if( isset( $_GET["page"] ) && $_GET["page"] === 'edit-foo' ){ <-- This line prevents the call 'wp_ajax_foo' !
        add_action( 'admin_init', array($this, 'init') );
   }
}

init(){
    ... <- initalize $this->editable_item->item
    add_action('wp_ajax_foo',array( $this->editable_item->item, 'foo' ) );
}

Answer 1

As foo is a static function you don't need to specify the object, so you can use it outside the condition to correctly load it like this :

 public function __construct(){
    if( isset( $_GET["page"] ) && $_GET["page"] === 'edit-foo' ){
        add_action( 'admin_init', array($this, 'init') );
    }
    add_action('wp_ajax_foo',array( 'MyPlugin/Classes/MyClassWithFooFunction', 'foo' ) );
 }

 init(){
     ... <- initalize $this->editable_item->item
 }