如何在Laravel 5中使用Eloquent查询数据透视表

Question

I have a many-to-many relationship between my client and tag tables. A client can have many tags, and each tag can be related to multiple clients.

On the client show view, I'm trying to display the client info plus all tags associated to this client.

How do I change the query below to retrieve the client rows with all its related tags?

public function show($id)
{
    $client = Client::findOrFail($id);

    return view('clients.show')->with(['client' => $client]);
}

Client model

public function clienttag()
{
    return $this->belongsToMany('App\Clienttag');
}

Clienttag model

public function client()
{
    return $this->belongsToMany('App\Client');
}

Client_clientags table migration

public function up()
{
    Schema::create('client_clienttag', function(Blueprint $table)
    {
        $table->integer('client_id')->unsigned();
        $table->foreign('client_id')->references('id')->on('clients')->onDelete('cascade');

        $table->integer('clienttag_id')->unsigned();
        $table->foreign('clienttag_id')->references('id')->on('clienttags')->onDelete('cascade');

        $table->timestamps();
    });
}   

Clients table migration

public function up()
{
    Schema::create('clients', function(Blueprint $table)
    {
        $table->increments('id');

        $table->string('first_name');
        $table->string('last_name');

        $table->rememberToken();
        $table->timestamps();
    });
}

Clienttags table migration

public function up()
{
    Schema::create('clienttags', function(Blueprint $table)
    {
        $table->increments('id');

        $table->string('tag');
        $table->text('description');

        $table->rememberToken();
        $table->timestamps();
    });
}

Answer 1

You can use "Eager Loading" methods like the following

public function show($id)
{
$client = Client::with('clienttag')->findOrFail($id);

return view('clients.show')->with(['client' => $client]);
}

Check documentation at http://laravel.com/docs/5.1/eloquent-relationships#eager-loading

Then at your view you can print your tags

 @foreach ($client->clienttag as $tag)
  {!! $tag->tagname!!} (or whatever your field in clienttags table name is)
 @endforeach