Filters usually used in filament tables in the table method $table->filters()

1// ...
2public function table(Table $table): Table
3{
4    return $table
5        ->filters([ 
6            ....
7        ]),
8}

Your First Filter

Let's say we have a table contains posts, and each post has category, so, let's create a custom filter, to filter posts by category.

Pre-requist

First we need to have a PostResource, and Category model relationship.

1...
2class Post extends Model
3{
4    public function category(): BelongsTo
5    {
6        return $this->belongsTo(Category::class);
7    }
8}

Create The Filter

In your app/Filament/PostResource folder. Create a new folder called Filters, and you can create the class CategoryFilter.

Let's first create the class, then we'll explain what's inside, shall we

 1<?php
 2 
 3namespace App\Filament\Resources\PostResource\Filters;
 4 
 5use Filament\Tables\Filters\SelectFilter;
 6 
 7class CategoryFilter extends SelectFilter
 8{
 9    public static function getDefaultName(): ?string
10    {
11        return 'category';
12    }
13 
14    protected function setUp(): void
15    {
16        parent::setUp();
17 
18        $this->label('Filter By Category');
19 
20        $this->placeholder('Select a category to filter');
21 
22        $this->relationship('category', 'name');
23 
24        $this->searchable();
25    }
26}

Let's explain the above filter

• We extends SelectFilter filament class, to filter by dropdown
• getDefaultName, is the name of your custom filter, to use it when you need it.
• we extends the parent setUp of the SelectFilter class to make our own modifications
• the label is self explanatory, to set a label for the filter
• the placeholder, is also self explanatory
• the relationship, is the method to the categories relationship
• the searchable method, is to make the dropdown searchable.

PS: You can use pretty much every method came with the Select component.

Apply it

If you want to apply this filter in PostResource. Do the following

1public function table(Table $table): Table
2{
3    return $table
4        ->filters([
5            CategoryFilter::make(), 
6        ]),
7}

Other Filters To Choose From

Filament came by default with multiple classes to support filtering system, which is

• Filter: the default filter class to choose
• SelectFilter: to select between multiple options
• TernaryFilter: to set a boolean filteration

Conclusion

Custom Filters in filament are very handy if you are the type of developer who like to take control, and use something in multiple places, and with custom filters you can use even form method to make your filter more advanced, and serve your needs.

This is all what I have today, hope you learn something from it, and see yea in another article.

Peace ✌️