I want to add an EAV model to my app. So I made these tables to do that:

Schema::create('attributes', function(Blueprint $table)
{
	$table->increments('id');
	$table->string('entity');	// this will contain the model class name, for example "App\User"
	$table->string('name');
	$table->smallInteger('index')->unsigned();
	$table->enum('type',
			[
				'text',
				'number',
				'date',
				'time',
				'datetime',
				'options'
			]
		)->default('text');
	$table->string('min');
	$table->string('max');
	$table->string('step');
	$table->json('options');
	$table->boolean('filterable')->default(true);
});

Schema::create('attribute_values', function(Blueprint $table)
{
	$table->integer('attribute_id')->unsigned();
	$table->integer('attributable_id')->unsigned();	// this will contain the id of the user for example
	$table->text('value');
	$table->primary(['attribute_id', 'attributable_id']);
	$table->foreign('attribute_id')
		  ->references('id')
		  ->on('attributes')
		  ->onDelete('cascade');
});

Now what I would like to do is make a trait that I can add to my models called Attributable. This trait should do a few things, but I think if I can learn how to make one of those features with a little bit of help then I can make the other ones without help.

So the feature I'd like a little help with the following. Imagine you add this trait to a user model which by itself has a username column and a password column. And now with this trait you are also adding a "hair color" attribute and an "age" attribute. I want, when one uses $user->find(1)->toArray() this to be returned:

[
    'id' => 1,
    'username' => 'admin',
    'password' => '******',
    'attributes' => [
        'hair color' => 'red',
        'age' => '28'
    ]
]

I honestly have no idea how to do that and I can't find any tutorials on it. Would someone please like to tell me how I could do this?