CakePHP how to submit NULL value? - cakephp

Question

On web form I have select-option field. It have to submit value 'card' (without quotes), or NULL value.
Now, code looks like this:
$options = array(NULL => 'Invoice', 'card' => 'Payment card');
echo $this->Form->input('payment_method', array('options'=>$options));
How can I define options array, to submit NULL value in database table (and/or 'card', but that works of course), in case that Invoice option is selected?
Thank you in advance!

Answer 1

NULL is an invalid key for an associative array. Only 'integers' and 'strings' are valid array keys, see the documentation: Arrays
To send an empty value through the form, you can use an empty string. To force inserting a NULL value in the database, handle this inside your model or controller before saving
$options = array('' => 'Invoice', 'card' => 'Payment card');
echo $this->Form->input('payment_method', array('options'=>$options));
Then inside your controller;
if ('' === $this->request->data['MyModelName']['payment_method']) {
this->request->data['MyModelName']['payment_method'] = null;
}
Alternative approach
However, why not use a value for the 'invoice' payment method? Like this:
echo $this->Form->input('payment_method', array(
'options' => array(
'' => 'Select your payment method..',
'invoice' => 'Invoice',
'card' => 'Payment card',
)
));
IMO this has some advantages;
it's more transparent, e.g. When looking inside the database, it's clear that the payment method is 'invoice'. By using a 'special' value (null), people without knowledge of your applications inner workings will have to browse through the source code to find out
it's possible to check if the use has selected a payment method; e.g. If the value is empty, the use may have forgotten to select a payment method, in which case you can mark the field 'invalid' via a validation rule.