<?php

class Index{
    
    // item_id / item_type
    public function item(){
        return $this->morphTo();
    }

}


class SampleItem{

    public function indexes(){
        return $this->morphMany('Index', 'item');
    }

    public function user(){
        return $this->belongsTo('User');
    }

} 

class User{
    //
}


// This nicely eager loads all of the morphed relations
$items = Index::with('item')->get();

// Accessing the "user" property on a item would result in a query every time.
foreach($items as $item){
    $test = $item->user;
}