Converting a scalar value (from a checkbox) to a boolean

Question

Depending on the submission-mechanism of an HTML form, any checkbox element values may be seen as 'on', 'off', 1, 0, 'true', 'false'. For this problem an unchecked input field will be also be submitted (because that's what I want) and it may appear as 0 or no or false.

The purpose here is to convert scalar values that logically represent a boolean value to a boolean variable. Such as:

• "yes" => true
• "no" => false
• "false" => false
• 0 => false
• 1 => true

Is there a helper in the Laravel framework that can "cast" a submitted FormData checkbox (or a plain form) to a boolean?

I could roll my own, but asking here is worth a shot.

Here is what I would use:

<?php


function checkbox_boolean($parameter) {
    if (is_bool($parameter)) return $parameter;
    if (is_object($parameter)) return count(get_object_vars($parameter)) !== 0;
    if (is_array($parameter)) return count($parameter) !== 0;
    if (is_numeric($parameter)) { return (boolean) $parameter; }
    $p = is_string($parameter) ? strtolower($parameter) : $parameter;

    switch ($p) {
        case 'yes';
        case 'on';
        case 'true';
            return true;
            break;

        case null;
        case 'no';
        case 'off';
        case 'false';
            return false;
            break;
    }
    return false;
}

These are the most common cases I would like to cover:

<?php
print_r([
    'yes' => [
        '"true"' => checkbox_boolean('true'),
        'true' => checkbox_boolean(true),
        '1' => checkbox_boolean(1),
        '"1"' => checkbox_boolean('1'),
        'yes' => checkbox_boolean('yes'),
        'YEs' => checkbox_boolean('YEs'),
        '<non-empty object>' => checkbox_boolean((object) [ 'z' => 'z']),
        '<non-empty array[0]>' => checkbox_boolean([0]),
    ],
    'no' => [
        '"false"' => checkbox_boolean('false'),
        'false' => checkbox_boolean(false),
        '0' => checkbox_boolean(0),
        '"0"' => checkbox_boolean('0'),
        'no' => checkbox_boolean('no'),
        'No' => checkbox_boolean('No'),
        '<empty object>' => checkbox_boolean(new stdClass),
        '<empty array []>' => checkbox_boolean([]),
    ]
]);

---

This question is not a duplicate of "How to convert strings to boolean" because this is not a generic problem.

I am asking about the specific process of converting HTML forms, or rather checkbox elements to a boolean. An important part of the question/problem is identifying the common values that these checkboxes generate when submitted by various (common) methods and parsed by PHP. In retrospect this does not make much sense because the value can be 100% arbitrary and set via the value= attribute of the input element.

---

According to this article, the canonical way would be something like the following and would return;

• true for: "1", "true", "on" and "yes".
• false for: "0", "false", "off", "no", and ""
• null otherwise

if (filter_has_var(INPUT_POST, 'agree')) {
    $agree = filter_input(INPUT_POST, 'agree', 
                 FILTER_VALIDATE_BOOLEAN,
                 [FILTER_NULL_ON_FAILURE]);
    if (! is_null($agree)) {
        ... 
    }
}

Resources:

• https://www.phptutorial.net/php-tutorial/php-checkbox/
• https://www.phptutorial.net/php-tutorial/php-filter_has_var/
• https://www.php.net/manual/en/function.filter-input.php
• https://www.php.net/manual/en/filter.filters.validate.php

Answer 1

This answer has nothing to do with Laravel, but offers a generic PHP solution.

When a form is submitted, all text-like fields are included, even if they are empty. This includes type="text", any of the newer types such as email and date as well as all unknown types such as type="testing". It also includes textarea.

As for buttons, only those which have been selected are included; unselected buttons will be absent. In practical terms, selected buttons will include 0 or more check boxes, only one (if any) radio button in a group, and the submit button selected.

The important thing about buttons is that selected buttons will be sent, but unselected ones won’t. This is regardless of the actual values of the buttons.

You can check for a checkbox, regardless of whatever value it is supposed to have, by testing its existence. For example, if you have a POST form with

<input type="checkbox" name="ok">

you can check for it using:

$ok = isset($_POST['ok']);

Some developers prefer to express the test as:

$ok = array_key_exists($_POST,'ok');

In both cases, the result is strictly boolean.

EDIT: Simplifying

There is a simple trick which allows you to assume that the checkbox always has a value:

<input name="ok" type="hidden" value="0">
<input name="ok" type="checkbox" value="1">

The checkbox shadows the hidden input, but only if it’s set. Otherwise the hidden input will be set instead.

At the PHP end, the vale of $_POST['ok'] will always be 0 or 1. You can use something like this:

$ok = !!$_POST['ok'];

Answer 2

In my case the checkbox returns "on" or "null", so in the controller I just do a IF statement:

 $checkbox_value = $request->checkbox_value ? 1 : 0

Hope it helps someone out there.

Mário

Answer 3

My code to convert checkbox name="home" to int. If the checkbox is checked -> issert = true <=> 1 If the checkbox is unchecked -> issert = false <=> 0

$data = $request->all();            
$data['home'] = isset($data['home'])? 1 : 0;

Answer 4

The checkbox_boolean($parameter) function in the question is good enough. You can even get it with composer.

Answer 5

Adding an attribute of value="1" to the input was the solution for me.