Question

I’m using codeigniter (MVC) and extjs for an application.
The application contains many extjs grids with user related data. I want to cache the server json response up to particular time.

i got an idea to implement this as follows

if(cache file exists and not expired)
{
  $data = read_file(cache file path);// the cache file contains json encoded data with .json extention
}
else
 {
   $result = call to a model function; // returns data from a mysql query
   $data = json_encode( $result );
   //creating cache file with retrived data
   wite_file(cache file path, $data)
 }
echo $data; // $data is in json format

i want to implement caching this way. Is it the correct way?.
Totally i want to implement a custom json caching library for caching server json data for extjs grids

Is there any json caching libraries already available for codeigniter.
Please help with your suggestions

Answer 1

Codeigniter has almost exactly what you describe built in. They refer to it as the Caching driver: http://codeigniter.com/user_guide/libraries/caching.html

In your case you would want to initiate it like this:

$this->load->driver('cache', array('adapter' => 'file', 'backup' => 'file'));

if ( ! $foo = $this->cache->get('foo'))
{
     echo 'Saving to the cache!<br />';
     $foo = 'foobarbaz!';

     // Save into the cache for 5 minutes
     $this->cache->save('foo', $foo, 300);
}

echo json_encode($foo); 

It will write the cache data to file.

The down side in your case is that CI serializes the data in the cache file as opposed to using JSON. I suppose you could override the driver using json_encode() instead of serialize(). The method above would waste a little bit of resources in that it is both serializing AND using json encoding on output.