Implementation of Zend_Db_Adapter_Mysqli to use Zend_Cache

fiskah · #1 (**permalink**) 03-28-2008, 04:40 PM

I've tried to make an implementation of Zend_Db_Adapter_Mysqli that adds a two parameters: bool cache, and int ttl. To specify whether to use caching, and if so how long the cache has to live.

The reason for this implementation is that I want to make it easier to cache database queries.

Code:

PHP Code:


			
<?php

class Site_Core_Database extends Zend_Db_Adapter_Mysqli

{

    function query($sql, $bind = array(), $cache = false, $cache_ttl = 3600)

    {

        // Do we want to use caching?

        if($cache !== true)

        {

            // No - perform the query

            return parent::query($sql, ($bind == null ? array() : $bind));

        } else {

            // Valid time to live (ttl)?

            if(!is_numeric($cache_ttl))

            {

                $cache_ttl = 3600;

            }

            

            // The cache object

            $cache = Zend_Registry::get('cache');

            

            // Generate cache key

            $key = md5($sql . serialize($bind));

            

            // Can we load the existing result?

            if(!($result = $cache->load($key)))

            {

                // If not generate a result

                $db = Zend_Registry::get('db');

                

                // Bind parameters

                if($bind != null)

                {

                    $result = $db->query($sql, $bind);

                } else {

                    $result = $db->query($sql);

                }

                $cache->save($result, $key, array('db'), $cache_ttl);

            }

            return $result;

        }

    }

}

?>

It seems though that there are trouble caching/serializing the result sets, because cache fetching fails.

Saving to the cache works fine, but when I reload the page I get this error:

Quote:

Warning: mysqli_stmt::fetch() [function.mysqli-stmt-fetch]: Couldn't fetch mysqli_stmt in [...]/lib/Zend/Db/Statement/Mysqli.php on line 271

Warning: mysqli_stmt::reset() [function.mysqli-stmt-reset]: Couldn't fetch mysqli_stmt in [...]/lib/Zend/Db/Statement/Mysqli.php on line 275

Anyone got a clue what I can do to implement a caching solution this way?

Thanks in advance.

pun_Krawk · #2 (**permalink**) 10-31-2008, 10:25 PM

Months later, I wanted to add to this (moreso for newbies like me than anyone else). I wanted to start using Zend_Cache and kept getting the same errors as fiskah had. This was the only search result that even discussed it.

I believe the issue is that we were attempting to cache a Zend_Db_Statement_Mysqli object, which was the returned result from (something similary to) $db->query($query);.

Unfortunately, when grabbed from the cache, you no longer have access to its methods, such as fetch(), so you get an error.

For me, the solution is to use fetchAll() instead of query(). fetchAll() returns a simple array, which can be accessed from the cache using a foreach loop.

If I stated anything wrong, please correct me.

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