Many-to-Many Eloquent relationship update with Laravel Form Model Binding & Checkboxes

Question

I have 3 tables:

doors

• id
• name
• image

colors

• id
• name
• image

door_colors

• id
• door_id
• color_id

and 2 models with a many-to-many relationship (each door comes in a variety colors, and many colors overlap door-to-door):

Door Model

class Door extends Eloquent {
    public function colors()
    {
        return $this->belongsToMany('Color', 'door_colors');
    }
}

Color Model

class Color extends Eloquent {
    public function doors()
    {
        return $this->belongsToMany('Door', 'door_colors');
    }
}

I want to create a form where I can edit the door, and update the available colors via checkboxes. This is my Admin Doors Controller

class AdminDoorsController extends AdminController {
    public function edit($id)
    {
        $data['door'] = Door::find($id);
        $data['colors'] = Color::all();
        return View::make('admin/doors/form', $data);
    }
}

and the Admin Doors Form View

{{ Form::model($door) }}
Colors:
@foreach ($colors as $color)
{{ Form::checkbox('colors[]', $color->id) }} {{ $color->name }}
@endforeach
{{ Form::close() }}

Question 1: How do I make it so that as the checkboxes are outputted, the ones with an existing relationship with the current door are checked and the ones without are unchecked.

Question 2: Once I check the boxes and hit submit, how would I update the relationships? $door->colors()->detach(); to clear all existing ones for this door, then $door->colors()->attach($color_id_array); to create new ones based on an array of color ids?

Any input is appreciated!

Answer 1

Question 1: You should pass this into the view that contains your form, though it can also go right in the view, though that's not really best practice. Do something similar to this...

$checkeds = Door::find(1)->colors()->lists('id');

...where the door you are finding is the door that's being updated. Then before you output the checkbox in the loop, add

$checked = in_array($color->id, $checkeds) ? true : false;

Then you would change

{{ Form::checkbox('colors[]', $color->id) }} 
{{ $color->name }}` 

to

{{ Form::checkbox('colors[]', $color->id, $checked) }}
{{ $color->name }}

Question 2: There is actually a perfect method given to you for this. Use

$door->colors()->sync(Input::get('colors'));

It will both delete the old ones and add all the new ones in one shot.