use when in laravel query eloquent code example

Example 1: laravel fillable

/**
     * The attributes that are mass assignable.
     */
    protected $fillable = [
      					   'title',
                           'slug',
                           'body',
                           'image',
                           'published',
                           'comments_open'
                          ];

Example 2: laravel find query

foreach (Flight::where('foo', 'bar')->cursor() as $flight) {
    //
}