php - Laravel checkbox state after failed validation

There are many many questions here on SO about how to properly persist checkbox fields in Laravel after form submission (
example,
example,
example
), this question is not about that.

Please note I am also well aware of Laravel's old() method, and that it accepts a default value. My question is about a particular case where old() does not seem to work for a checkbox.

I'm working on an edit form, updating data already in the DB. The form will initially be populated with the values from the DB.

The standard approach to re-populating form inputs after failed validation is to use old(). For most input types, something like the following works:

unicorns) }}'>

On initial page load (before the form is submitted) this works fine. As nothing has been submitted yet, old('unicorns') is null, so the default of $model->unicorns will be used, and the text field's value reflects the current DB state.

After submitting a new value, which fails validation, old('unicorns') will be the new value, even if the new value was an empty string, and again the text field's value reflects the submitted state, as we want.

However this breaks down for checkboxes, when the unchecked checkbox does not appear in the request at all. Consider:

unicorns) checked @endif>

On initial page load this works fine, just like for text fields. But after failed validation, for the 2 cases where the checkbox is changed from its initial state:

• Case 1: DB state 0 (unchecked), submitted state checked. old('unicorns') will be 1, so the test evaluates true, the checkbox is checked - OK!





• Case 2: DB state 1 (checked), submitted state unchecked. Since old('unicorns') is null, old() falls back to the default value $model->unicorns (1), so the test evaluates true, and the checkbox is checked - but we just unchecked it! FAIL!

(There is no problem in the other 2 cases, where the checkbox is not changed from the state in the DB).

How to solve this?

I initially thought the best way around this would be to test if there has been a validation error - if so, use the old() value, with no default fallback; if not, use old() with default fallback. One way to test for failed validation is to check $errors. This seems to work, but it only works within a view AFAICT, as (from the Laravel docs):

Note: The $errors variable is bound to the view ...

I'd like to create a global helper for this, and $errors won't work there. Anyway, this approach feels ... clunky and too complicated.

Am I missing something? Is there a neat Laravel way of solving this? It seems odd that old() simply does not work for this particular case.

This is not a new problem, how do others handle this?

Answer

This is the solution I referred to in my question. It works well, and 6 months later, it does not seem as clunky as when I posted the question. I'd be happy to hear how others are doing this though.

I have an Html helper, created as described in this question, and aliased in config/app.php as described in the first part of this answer to that question. I added a static method to it:

namespace App\Helpers;
use Illuminate\Support\ViewErrorBag;

class Html {
    /**
     * Shortcut for populating checkbox state on forms.
     *

     * If there are failed validation errors, we should use the old() state
     * of the checkbox, ignoring the current DB state of the field; otherwise
     * just use the DB value.
     *
     * @param string $name The input field name
     * @param string $value The current DB value
     * @return string 'checked' or null;
     */
    public static function checked($name, $value) {
        $errors = session('errors');


        if (isset($errors) && $errors instanceof ViewErrorBag && $errors->any()) {
            return old($name) ? 'checked' : '';
        }

        return ($value) ? 'checked' : '';
    }
}

Now in my views I can use it like so:

unicorns) }}>

This correctly handles all combinations of DB and submitted state, on initial load and after failed validation.