> ## Documentation Index
> Fetch the complete documentation index at: https://docs.eloquentfiltering.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Required Filters

## Overview

You can specify that `Filter::field()`, `Filter::relation()`, `Filter::morphRelation()`, `Filter::morphType()` and `Filter::custom()` filters must be required.

* When a required filter is not used, a `RequiredFilterException` is thrown.
* `RequiredFilterException` extends Laravels `ValidationException`.
  * You can let this bubble up to your controller for the default laravel 422 response.
* This exception **CAN NOT** be [suppressed](/v2/digging-deeper/suppressing-exceptions).

## Marking As Required

```php {7,13,15,25,27,28,32} theme={null}
public function allowedFilters(): AllowedFilterList
{
    return Filter::only(
        /*
         * Field
         */
        Filter::field('name', [FilterType::LIKE])->required(),
        /*
         * Relation
         */
        Filter::relation('books', [FilterType::HAS],
            Filter::only(
                Filter::field('title', [FilterType::LIKE])->required()
            )
        )->required(),
        /*
         * Morph Relation
         */
        Filter::morphRelation('imageable', [FilterType::HAS_MORPH],
            /*
             * Morph Type
             */
            Filter::morphType(Article::class,
                Filter::only(
                    Filter::field('title', [FilterType::LIKE])->required()
                )
            )->required()
        )->required(),
        /*
         * Custom
         */
        Filter::custom('$latest')->required()
    );
}

Model::filter([]);
// RequiredFilterException errors
[
    'name' => [
        'Name filter is required.',
    ],
    'books' => [
        'Books filter is required.',
    ],
    'books.title' => [
        'Title filter is required.',
    ],
    'imageable' => [
        'Imageable filter is required.',
    ],
    'imageable.articles' => [
        'Articles filter is required.',
    ],
    'imageable.articles.title' => [
        'Title filter is required.',
    ],
    '$latest' => [
        '$latest filter is required.',
    ],
]
```

## Relaxing The Required Scope

* Sometimes you may want a filter to be required **ONLY** if it's parent has been filtered.
  * You can set the `scoped` parameter to `true` to achieve this.

```php {7} theme={null}
public function allowedFilters(): AllowedFilterList
{
    return Filter::only(
        Filter::relation('books', [FilterType::HAS],
            Filter::only(
                Filter::field('title', [FilterType::LIKE])
                    ->required(scoped: true)
            )
        ),
    );
}

Model::filter([]);
// 'books' relation filter not used
// RequiredFilterException not thrown.

Model::filter([
    [
        'target' => 'books',
        'type' => '$has',
    ]
]);
// 'books' relation filter used
// RequiredFilterException errors
[
    'books.title' => [
        'Title filter is required.',
    ],
]
```