What result do you expect exactly?

I would expect the responding array to contain the Appends attribute. In this case the pin.

For instance the the setAppends works as follows:

$account = Account::find(1);
$account->setAppends(array('pin'));
$account->toJSON(); 

And it's result something like (includes pin because of setAppends):

{
    "name": "Account1",
    "type": "blue",
    "pin": 1234
}

Now the append through a relationship (or eager load) ideally would be able to also use setAppends:

$user = User::find(1);
$user->setAppends(array('pin')); 
/* or $user->account->setAppends(array('pin')); */
$user->toJSON();

And it's expected result something like:

{
    "first_name": "Bob",
    "last_name": "Hope",
    "account": {
        "name": "Account1",
        "type": "blue",
        "pin": 1234
    }
}

However the 'pin' doesn't get included as expected as hoped.

Bump up!

At the time of this writing the only way of doing what you want is manually.

$account = Account::find(1);
$account->pin = $account->pin;
$account->toJSON();

Since then I made a commit to the framework adding the append() method.

Now you use it like this:

$account = Account::find(1)->append('pin')->toJSON();