问建立这种拉拉维尔关系的正确方式？

EN

/**
 * Indicate that the model belongs to a user.
 *
 * @see \App\Model\User
 *
 * @return BelongsTo
 */
public function user()
{
    return $this->belongsTo(User::class);
}

/**
 * Indicate that the model belongs to many activity participations.
 *
 * @see \App\Model\Activity
 *
 * @return BelongsTo
 */
public function participations()
{
    return $this->belongsToMany(Activity::class, 'participations');
}

$user->participations()->attach($activity);

/* in User */
public function activity()
{
    return $this->belongsToMany('App\Models\Activitys','participation','user_id','activity_id')->as('participation')->withPivot('time_at_activity');
} 

/* in Activity */
public function user()
{
    return $this->belongsToMany('App\Models\Users','participation','activity_id','user_id')->as('participation')->withPivot('time_at_activity');
} 

// App\User
public function participations()
{
    return $this->hasMany('App\Participation');
} 
// You may create App\Participation Model
// App\Participation 
public function user()
{
    return $this->belongsTo('App\User');
} 

// Controller
$userParticipations = $user->participations->where('activity_id', 3);
// eager loading version
$userWithParticipations = $user->with(['participations' => function($q) { $q->where('activity_id', 3) }])->get();