Attaching records using the Repeater field and HasMany by Patrick Boivin - Tricks

Context

Let's say you want to associate Players to Teams in your application. After reading the Laravel Documentation, you create this database table structure:

teams
    id - integer
    name - string
 
players
    id - integer
    name - string
 
team_player
    player_id - integer
    team_id - integer

You create the corresponding Player model with a BelongsToMany relationship to the Team model

class Player extends Model
{
    protected $fillable = ['name'];
 
    public function teams()
    {
        return $this->belongsToMany(Team::class, 'team_player');
    }
}
 
class Team extends Model
{
    protected $fillable = ['name'];
 
    public function players()
    {
        return $this->belongsToMany(Player::class, 'team_player');
    }
}

You then attach Players to a Team by calling $team->attach([$player->id]), all is good!

Problem

Now in Filament, in your TeamResource, you add a Repeater field to let your site administrators attach Players to Teams:

public static function form(Form $form): Form
{
    return $form
        ->schema([
            TextInput::make('name'),
 
            Repeater::make('players')
                ->relationship()
                ->schema([
                    Select::make('player_id')
                        ->label('Player')
                        ->options(Player::pluck('name', 'id')),
                ]),
        ]);
}

When you try to add a Player to a Team using the Repeater field and save, you see this error:

SQLSTATE[23000]: Integrity constraint violation: 19 NOT NULL constraint failed: players.name
 
INSERT INTO "players" ("updated_at", "created_at") VALUES (2023-07-17 13:55:12, 2023-07-17 13:55:12)

What's happening? Filament is trying to create a new Player record instead of simply attaching the selected Player to the Team.

Solution

Introduce a new TeamPlayer model:

class TeamPlayer extends Model
{
    protected $table = 'team_player';
 
    protected $fillable = ['team_id', 'player_id'];
}

Update your team_player table schema:

Schema::create('team_player', function (Blueprint $table) {
    $table->id();
    $table->integer('team_id');
    $table->integer('player_id');
    $table->timestamps();
});

Update your Team-Player relationship to HasMany instead of BelongsToMany:

class Team extends Model
{
    protected $fillable = ['name'];
 
    public function teamPlayers()
    {
        return $this->hasMany(TeamPlayer::class, 'team_id', 'id');
    }
}

Update your Repeater field name:

Repeater::make('teamPlayers')
    ->relationship()
    ->schema([
        Select::make('player_id')
            ->label('Player')
            ->options(Player::pluck('name', 'id')),
    ]),