In Laravel, how can I keep the selected options of a multiselect on an invalid form?

In Laravel, how can I keep the selected options of a multiselect on an invalid form?

To keep the selected options of a multiselect input in Laravel when the form is invalid, you can use JavaScript to manipulate the DOM and restore the selected values after an error occurs. Here's a step-by-step guide on how to achieve this:

1. In your Laravel view file, add a unique ID to the multiselect input. This ID will be used in the JavaScript code to target the specific input element.

{!! Form::label('categories[]', 'Select Categories:') !!}
{!! Form::select('categories[]', $categories, old('categories') ?? [], ['id' => 'categories-select', 'multiple']) !!}

2. Add the following JavaScript code to your view file, either by adding it directly in the <script> tag or by creating a separate JavaScript file and linking it in the view.

document.addEventListener('DOMContentLoaded', function() {
    const form = document.querySelector('form');

    form.addEventListener('submit', function(event) {
        event.preventDefault();

        const categoriesSelect = document.getElementById('categories-select');
        const categoriesValues = categoriesSelect.value;

        // Submit the form using AJAX or the default method
        // ...

        // On form validation error, restore the selected values
        form.addEventListener('invalid', function(event) {
            event.preventDefault();

            // Get the first error message
            const error = event.target.reportValidity().messages[0];

            // If the error message is related to the multiselect input, restore the selected values
            if (error.includes('categories')) {
                categoriesSelect.value = categoriesValues;
            }
        });
    });
});

This JavaScript code listens for the form submission event and prevents the default behavior. It then stores the selected values of the multiselect input in a variable. When the form is invalid, it listens for the invalid event and checks if the error message is related to the multiselect input. If it is, the script restores the selected values by setting the input's value to the stored values.

3. If you're using AJAX to submit the form, make sure to update the JavaScript code accordingly to submit the form using AJAX and handle the response.

With these steps, the selected options of the multiselect input will be kept when the form is invalid in Laravel.