Calculate Different Integers + Inject new totals to Database - laravel-4

Question

I've been searching endlessly for a clue on how I should properly go about creating a "Money Transfer" function (for a game, not real money) within Laravel 4.2.
Needlessly to say, I've come up empty handed and I'm turning to you guys.
The task:
Transfer funds from "Spending" to "Saving" accounts (or vice-versa)
Subtract the amount from the account it's exiting.
Add the amount to the account it's entering.
What I need:
A simple calculation to help me get started on building this out. I'm quite new to writing Eloquent and simply need someone to outline how this sort of thing should work.
Database:
id, user_id, spending, saving, bucks, pin, created_at, updated_at
Model:
class Bank extends Eloquent {
protected $table = 'banks';
protected $fillable = ['user_id, spending, saving, bucks, pin'];
// Connect to the User
public function user()
{
return $this->belongsTo('User');
}
}
Controller:
public function transferMoney()
{
$id = Auth::id();
$bank = Bank::find($id);
$spending = $bank->spending;
$saving = $bank->saving;
$transfer_type = Input::get('transfer_to');
$transfer_amount = Input::get('amount');
// Spending to Savings
if($transfer_type = 1) {
if($transfer_amount >= $spending) {
// the magic to transfer the funds goes here.
}
}
// Savings to Spending
if($transfer_type = 2) {
if($transfer_amount >= $savings) {
// the magic to transfer the funds goes here.
}
}
}
Form in View:
{{ Form::open(array('route' => array('transferMoney'), 'method' => 'post')) }}
{{ Form::select('transfer_to', array('1' => 'Spending to Saving', '2' => 'Saving to Spending')) }}
{{ Form::text('amount', null, ['placeholder' => 'Amount']) }}
{{ Form::submit('Transfer', array('class' => 'button secondary pull-right')) }}
{{ Form::close() }}
Route:
Route::post('/bank', array('as' => 'transferMoney', 'uses' => 'BankController#transferMoney'));
Any tips & tricks on best practices are hugely appreciated!
Apologies if this repeated - I swear I can't find a solution to this specific roadblock.
Thank you!

Answer 1

I believe you'll need to subtract the amount ($transfer_amount) from the transfer-er and add it to the transfer-ee
public function transferMoney()
{
$id = Auth::id();
$bank = Bank::find($id);
$transfer_type = Input::get('transfer_to');
$transfer_amount = Input::get('amount');
// Spending to Savings
if($transfer_type == 1)
{
if($transfer_amount > $bank->spending)
{
// Error - insufficient funds
}
else
{
$bank->spending -= $amount;
$bank->saving += $amount;
$bank->save();
}
}
// Savings to Spending
if($transfer_type == 2)
{
if($transfer_amount > $bank->saving)
{
// Error - insufficient funds
}
else
{
$bank->spending += $amount;
$bank->saving -= $amount;
$bank->save();
}
}
}
I also fixed a few syntactical things (if($transfer_type = 1) needs more than one =).
Make sure you validate that the transfer amount is a valid number! :)