Laravel Tips 之 forelse

我们在Laravel Blade模板中经常在循环输出前先判断一下集合是否有值，然后再foreach 比如:

@if ($posts->count())
  @foreach ($posts as $post)
    <p>This is post {{ $user->id }}</p>
  @endforeach
@else
  <p>No posts found.</p>
@endif

其实在Laravel Blade中可以使用forelse:

@forelse ($posts as $post)
    <p>This is post {{ $post->id }}</p>
@empty
    <p>No posts found.</p>
@endforelse

它的实现可以在Illuminate/View/Compilers/BladeCompiler.php找到：

   /**
     * Compile the forelse statements into valid PHP.
     *
     * @param  string  $expression
     * @return string
     */
    protected function compileForelse($expression)
    {
        $empty = '$__empty_'.++$this->forelseCounter;

        return " {$empty} = true; foreach{$expression}: {$empty} = false; ?>";
    }

from : https://yuansir-web.com/2016/07/11/laravel-tips-zhi-forelse/