Master / Slave switch in the Zend Framework application layer

Question

I am writing an application which requires the Master/Slave switch to happen inside the application layer. As it is right now, I instantiate a Zend_Db_Table object on creation of the mapper, and then setDefaultAdapter to the slave.

Now inside of the base mapper classe, I have the following method:

public function useWriteAdapter()
{
    if(Zend_Db_Table_Abstract::getDefaultAdapter() != $this->_writeDb)
    {
        Zend_Db_Table_Abstract::setDefaultAdapter($this->_writeDb);
        $this->_tableGateway = new Zend_Db_Table($this->_tableName);
    }
}

I need a sanity check on this. I don't think the overhead is too much, I just suspect there must be a better way.

Answer 1

How about something like a base class that you extend which performs the startup?

class My_Db_Table extends Zend_Db_Table
{
    function init() 
    {
        if (....) {
           // set the default adaptor to the write-DB-master
        }
        parent::init();
    }
}
// all your models then extend My_Db_Table instead of Zend_Db_Table

Answer 2

An object of type Zend_Db_Table_Row_Abstract remembers what Table object produced it. But you can change the associated Table before you call save().

$readDb = Zend_Db::factory(...);  // slave
$writeDb = Zend_Db::factory(...); // master
Zend_Db_Table::setDefaultAdapter($readDb);

$myReadTable = new MyTable(); // use default adapter
$myWriteTable = new MyTable($writeDb);

$row = $myTable->find(1234)->current();

$row->column1 = 'value';

$row->setTable($myWriteTable);

$row->save();