How to POST empty <select .. multiple> HTML elements if empty?

If your form is generated dynamically, you could include a hidden form element with the same name that contains a dummy value. Then, just ignore the dummy value, if the value you get for that variable is ['dummy_value'] then you can treat that as meaning "nothing selected" in your code.

If you add a hidden input before the multiple select element, it will send the hidden input value if none of the multiple select items have been selected. As soon as you select an option though, that selected value is used instead.

This way I was able to distinguish 2 different scenarios in Laravel/php, being:

• Set all myitems to empty (requiring the hidden input, so PHP receives an empty string for myitems)
• Update other properties of the model without touching myitems (so excluding any myitems input form the form. PHP will not receive the myitems key)

Sample code:

<input type="hidden" name="myitems" value="" /><select name="myitems[]" multiple>  <option value="1">Foo</option>  <option value="2">Bar</option></select>

Is there a reason you can't treat the situation where the array isn't set as if it was sent with no contents?

if (!isset($_POST['eng_0']))    $_POST['eng_0'] = array();

EDIT:

Add a hidden field whenever the multiple select is present in your form:

<input type="hidden" name="eng_0_exists" value="1"/>

Then check:

if (!isset($_POST['eng_0']) && isset($_POST['eng_0_exists']))    $_POST['eng_0'] = array();