Magento – Magento get read or write connection for model / resource model

databasemodel

I have 3 databases (in addition to the magento one) connected to magento with models (non-eav) defined for the tables.

They all have their read and write connections defined in the local.xml

        <cloudvm_db>
            <connection>
                <host><![CDATA[SERVER]]></host>
                <username><![CDATA[USER]]></username>
                <password><![CDATA[PASS]]></password>
                <dbname><![CDATA[cloudvm]]></dbname>
                <model>mysql4</model>
                <type>pdo_mysql</type>
                <active>1</active>
            </connection>
        </cloudvm_db>
        <cloudvm_read>
            <connection>
                <use>cloudvm_db</use>
            </connection>
        </cloudvm_read>
        <cloudvm_write>
            <connection>
                <use>cloudvm_db</use>
            </connection>
        </cloudvm_write>

then this is defined as the connection for the model in the modules config.xml

<models>
    <cloud_workervm>
      <class>Cloud_WorkerVM_Model</class>
      <resourceModel>cloud_workervm_resource</resourceModel>
    </cloud_workervm>
    <cloud_workervm_resource>
      <class>Cloud_WorkerVM_Model_Resource</class>
      <entities>
        <virtualmachine>
          <table>virtualmachine</table>
        </virtualmachine>
      </entities>
    </cloud_workervm_resource>          
  </models>
  <resources>
    <cloud_workervm_write>
      <connection>
        <use>cloudvm_write</use>
      </connection>
    </cloud_workervm_write>
    <cloud_workervm_read>
      <connection>
        <use>cloudvm_read</use>
      </connection>
    </cloud_workervm_read> 
  </resources>

what I am trying to do is write a function(s) that you can pass the name of a model e.g. "cloud_workervm/cloudvm" and return the name of (or an object of) the read connection and the write connection

Best Answer

Please follow bellow steps

Config.xml

    <?xml version="1.0"?>
<config>
    <modules>
        <AR_Externaldb>
            <version>0.1.0</version>
        </AR_Externaldb>
    </modules>
    <frontend>
        <routers>
            <externaldb>
                <use>standard</use>
                <args>
                    <module>AR_Externaldb</module>
                    <frontName>externaldb</frontName>
                </args>
            </externaldb>
        </routers>
        <layout>
            <updates>
                <externaldb>
                    <file>externaldb.xml</file>
                </externaldb>
            </updates>
        </layout>
    </frontend>
    <admin>
        <routers>
            <externaldb>
                <use>admin</use>
                <args>
                    <module>AR_Externaldb</module>
                    <frontName>externaldb</frontName>
                </args>
            </externaldb>
        </routers>
    </admin>
    <adminhtml>
        <layout>
            <updates>
                <externaldb>
                    <file>externaldb.xml</file>
                </externaldb>
            </updates>
        </layout>
    </adminhtml>
    <global>
        <models>
            <externaldb>
                <class>AR_Externaldb_Model</class>
                <resourceModel>externaldb_mysql4</resourceModel>
            </externaldb>
            <externaldb_mysql4>
                <class>AR_Externaldb_Model_Mysql4</class>
                <entities>
                    <vehicle><table>BaseVehicle</table></vehicle>
                </entities>
            </externaldb_mysql4>
        </models>
        <resources>
            <!-- End DB -1 --> 
            <externaldb_write>
                <connection>
                    <use>externaldb_database</use>
                </connection>
            </externaldb_write>
            <externaldb_read>
                <connection>
                    <use>externaldb_database</use>
                </connection>
            </externaldb_read>
            <externaldb_setup>
                <connection>
                    <use>core_setup</use>
                </connection>
            </externaldb_setup>
            <externaldb_database>
                <connection>
                    <host><![CDATA[localhost]]></host>
                    <username><![CDATA[testsql]]></username>
                    <password><![CDATA[test123]]></password>
                    <dbname><![CDATA[database-1]]></dbname>
                    <model>mysql4</model>
                    <type>pdo_mysql</type>
                    <active>1</active>
                </connection>
            </externaldb_database>
            <!-- End DB-1 --> 
            <!-- DB -2 -->
            <pcdb_write>
                <connection>
                  <use>pcdb_database</use>
                </connection>
            </pcdb_write>
            <pcdb_read>
                <connection>
                  <use>pcdb_database</use>
                </connection>
            </pcdb_read>
            <pcdb_setup>
                <connection>
                  <use>core_setup</use>
                </connection>
            </pcdb_setup>
            <pcdb_database>
                <connection>
                  <host><![CDATA[localhost]]></host>
                  <username><![CDATA[test]]></username>
                  <password><![CDATA[test123]]></password>
                  <dbname><![CDATA[database-2]]></dbname>
                  <model>mysql4</model>
                  <type>pdo_mysql</type>
                  <active>1</active>
                </connection>
            </pcdb_database>
            <!-- End DB -2 -->
        </resources>
        <blocks>
            <externaldb>
                <class>AR_Externaldb_Block</class>
            </externaldb>
        </blocks>
        <helpers>
            <externaldb>
                <class>AR_Externaldb_Helper</class>
            </externaldb>
        </helpers>
    </global>
</config>

Bellow Read & write function use in model or resource

<?php
class AR_Externaldb_Model_Test extends Mage_Core_Model_Abstract
{
protected $_readAdaptor;
protected $_readPcdbAdaptor;
protected $_writeAdaptor;

public function readAdaptor()
{
    if(empty($this->_readAdaptor)) {
        $this->_readAdaptor = Mage::getSingleton('core/resource')->getConnection('externaldb_read');
    }
    return $this->_readAdaptor;
}

public function writeAdaptor()
{
    if(empty($this->_writeAdaptor)) {
        $this->_writeAdaptor = Mage::getSingleton('core/resource')->getConnection('externaldb_write');
    }
    return $this->_writeAdaptor;
}

public function readPcdbAdaptor()
{
    if(empty($this->_readPcdbAdaptor)) {
        $this->_readPcdbAdaptor = Mage::getSingleton('core/resource')->getConnection('pcdb_read');
    }
    return $this->_readPcdbAdaptor;
}

}

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