我是否总是必须在 - > first（）之前调用 - > count（）以防止“模型[Foo]没有查询结果”？

Do I always have to check for $this->foo->count() before I can $this->foo->first() to "catch" any No query results for model [Foo]. "exceptions"?

I've tried this

public function hasValid($model)
{   
    try {
        return $this->$model()->firstOrFail()->expiration > date('Y-m-d') ? true : false;
    } catch(ModelNotFoundException $e) {
        return false;
    }
}

But I'm still getting No query results for model [Foo]. when the query returns an empty query set.

I don't always want to prepend any $this->foo->first() calls with a $this->foo->count() call just to check for this. There has to be a DRYer solution.

I've got this to be the DRYest so far:

public function hasValid($model)
{   
        $model = $this->$model()->first();
        return isset($model) && $model->expiration > date('Y-m-d') ? true : false;
}

You need use statement or full namespace for exception:

use Illuminate\Database\Eloquent\ModelNotFoundException;

// or:

catch(Illuminate\Database\Eloquent\ModelNotFoundException $e)

Also you can define default handler, so you can do simply this:

public function hasValid($model)
{   
  return ($this->$model()->firstOrFail()->expiration > date('Y-m-d')) ? true : false;
}

// in global.php or wherever, something like this:
App::error(function(Illuminate\Database\Eloquent\ModelNotFoundException $exception, $code)
{
    Log::error($exception);

    return Response::make('Not found', 404);
});