Laravel - Many to Many - Model binding - laravel

Question

I need some help.
I have these tables: users, buys and codecs. I have a many-to-many relationship: buys, codecs, buy_codec
Tables
Schema::create('codecs', function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->timestamps();
});
Schema::create('buys', function (Blueprint $table) {
$table->increments('id');
$table->integer('user_id')->unsigned();
$table->string('name');
});
Schema::create('buy_codec', function (Blueprint $table) {
$table->increments('id');
$table->integer('buy_id')->unsigned();
$table->foreign('buy_id')->references('id')->on('buys')->onDelete('cascade');
$table->integer('codec_id')->unsigned();
$table->foreign('codec_id')->references('id')->on('codecs')->onDelete('cascade');
$table->timestamps();
});
This is my controller:
class UserBuyController extends Controller
{
public function create($userId)
{
$codecs = Codec::lists('name', 'id');
$usr = User::findOrFail($userId);
return view('buy.create', compact('usr', 'codecs'));
}
public function store($userId, Request $request)
{
$codecs = $request->input('codecs');
$usr = User::findOrFail($userId)->buy()->create($request->except('codecs'));
$usr->codec()->sync($codecs);
return redirect('user/'.$userId.'/buy');
}
public function edit($userId, $id)
{
$codecs = Codec::lists('name', 'id');
$buy = User::findOrFail($userId)->buy()->findOrFail($id);
return view('buy.edit', compact('buy', 'codecs'));
}
}
Create form
{!! Form::open(['method'=>'POST', 'action'=>['UserBuyController#store', $usr->id]]) !!}
<div class="form-group">
{!! Form::label('name', 'Name:') !!}
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-font"></i></span>
{!! Form::text('name', null, ['class'=>'form-control']) !!}
</div>
</div>
<div class="form-group">
{!! Form::label('codecs', 'Outbound Codecs:') !!}
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-language"></i></span>
{!! Form::select('codecs[]', $codecs, null, ['class'=>'form-control', 'multiple'=>true]) !!}
</div>
</div>
{!! Form::submit('Submit', ['class'=>'btn btn-info']) !!}
{!! Form::close() !!}
And this is the edit form
{!! Form::model($buy,['url'=>url('user/'.$buy->user->id.'/buy/'.$buy->id),'method'=>'patch']) !!}
<div class="form-group">
{!! Form::label('name', 'Name:') !!}
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-font"></i></span>
{!! Form::text('name', null, ['class'=>'form-control']) !!}
</div>
</div>
<div class="form-group">
{!! Form::label('codecs', 'Outbound Codecs:') !!}
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-language"></i></span>
{!! Form::select('codecs[]', $codecs, null, ['class'=>'form-control', 'multiple'=>true]) !!}
</div>
</div>
{!! Form::submit('Update', ['class'=>'btn btn-info']) !!}
{!! Form::close() !!}
Model binding doesn't work
Something is wrong but I don't know what.
This is my pivot table. I have 2 codecs associated with buy_id 3
And this is my edit page.
Nothing is selected.
Update
Model
class Buy extends Model
{
protected $guarded = ['id'];
public function codec() {
return $this->belongsToMany('App\Codec');
}
public function user() {
return $this->belongsTo('App\User');
}
}
class Codec extends Model
{
protected $guarded = ['id'];
public function buy() {
return $this->belongsToMany('App\Buy');
}
}
class User extends Authenticatable
{
public function buy() {
return $this->hasMany('App\Buy');
}
}

Answer 1

One solution would be to create an accessor for the codec ids and use that with Form::select() instead:
In your Buy model add the following accessor:
public function getCodecListAttribute()
{
return $this->codecs->pluck('id')->toArray();
}
Then change you select block to:
<div class="form-group">
{!! Form::label('codec_list', 'Outbound Codecs:') !!}
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-language"></i></span>
{!! Form::select('codec_list[]', $codecs, null, ['class'=>'form-control', 'multiple'=>true]) !!}
</div>
</div>
This will mean that when you try to get the value from the request you will have to use codec_list instead of codecs.
Hope this helps!

Answer 2

in the edit form: {!! Form::select('codecs[]', $codecs, null, ['class'=>'form-control', 'multiple'=>true]) !!} the default selected value is set as null. You should set here the list of ids of the associated codecs.
Hope this helps.