使用nginx基于查询变量提供静态或动态文件

I have a php script that converts and saves a image thumbnail into a folder indicating its size.

For example by going to a url like 'http://website.com/thumbs/640x480/image.jpg' a thumbnail image would be created and saved in a folder that matches the url, so that next time the image is served statically. The php script uses the following location block:

location /thumbs/ {

    try_files $uri /thumbs/index.php?r=$uri&$query_string;

}

What I would like to do is regenerate the thumbnail image if there is an query argument such as ?nocache=1 appended to the thumbnail url.

I think that you need something like this:

location /thumbs/ {

   if ($arg_nocache) {
       rewrite ^(.*)$ /thumbs/index.php?r=$uri&$query_string break;
   }


    try_files $uri /thumbs/index.php?r=$uri&$query_string;

}