缩短url函数，需要两个ajax请求才能返回缩短的url字符串

Question

Using the Laravel framework, I made a few functions to generate shortened urls, the function works (almost), I have to do the ajax call twice to return the shortened url.

First ajax call receives a 500 error.

And here's the successful call the second time:

I'm confused how a function can work (but not really) at the same time.

EDIT (additional info):

/shorten is used for routing:

Route::post('/shorten', array('uses' => 'UrlController@shorten'));

functions:

Which further calls the shorten function in the UrlController:

public function shorten(){

    header('Content-type: text/plain');

    $long_url = $_POST['url'];
    $link = Link::checkOrShorten($long_url);

    return $link->short_url;
}

Ajax:

$(function() {
    $('#litlingit').click(function(){
      $.ajax({
        type: "POST",
        data: { url: $('input[name="long_url"]').val() },
        dataType: "text",
        url: "/shorten"
      }).done(function( data ){
        $('input[name="long_url"]').val('http://litl.it/'+data);
      });
  });
});

Module:

public static function checkOrShorten($long_url)
{

    $link = new Link;
    $link->users_id = NULL;

    if (Auth::check())
    {
        $link->users_id = Auth::user()->id;
    }

    $link->long_url = $long_url;
    $query = DB::select("select short_url from links where long_url = '$long_url'");
    if ($query) 
    {
        foreach ($query as $links)
        {
            $link->short_url = $links->short_url;
        }   
        $url_id = DB::select("select id from links where long_url = '$long_url'");
        DB::table('users_links')->insert(array('link_id' => $url_id[0]->id, 'user_id' => $link->users_id, 'privacy' => 0));
    }

    while(is_null($link->short_url)) 
    {
        $link->short_url = str_random(4);
        $query = DB::select("select short_url from links where short_url = '". $link->short_url ."'"); 

        if(!$query)
        {
            $link->save();
            $url_id = DB::select("select id from links where short_url = '$link->short_url'");
            DB::table('users_links')->insert(array('link_id' => $url_id, 'user_id' => $link->users_id, 'privacy' => 0));
        }
    }
    return $link;
}

Answer 1

Your shortener is working well, but in your first request an exception is being raised in Laravel:

{"error":{"type":"ErrorException","message":"ksort() expects parameter 1 to be array, null given","file":"\/var\/www\/litl.it\/vendor\/laravel\/framework\/src\/Illuminate\/Database\/Query\/Builder.php","line":1407}}

This error returns as a 500 error to javascript, that's normal.

But it creates the shortened url anyway, so in the second request it just returns the value you already have in database.

You should have information (call stack) about this in your Laravel log, run

php artisan tail

And try to shorten another one. As your site is live, I was able to do some tests online using Postman Chrome Extension: http://puu.sh/7IfXJ.png.

You might have a problem with this part of your code:

    if(!$query)
    {
        $link->save();
        $url_id = DB::select("select id from links where short_url = '$link->short_url'");
        DB::table('users_links')->insert(array('link_id' => $url_id, 'user_id' => $link->users_id, 'privacy' => 0));
    }

You are looking for a link as soon as you saved it in database and sometimes you might get a null, but, since you are saving it and Laravel tries to get the id back into your model, I think you can change it to:

    if(!$query)
    {
        $link->save();

        DB::table('users_links')->insert(array('link_id' => $link->id, 'user_id' => $link->users_id, 'privacy' => 0));
    }