如何在Magento模型中覆盖表名和前缀？

Question

I need to make Magento read/write data to an existing database table in order to integrate with another party system. The table cannot be renamed. If I specify it in the table tag in the model config as below magento adds the prefix. Is there a way to override the prefixing somehow?

   <models>
        <arithmetic>
            <class>Mcmr_Arithmetic_Model</class>
            <resourceModel>arithmetic_mysql4</resourceModel>
        </arithmetic>
        <arithmetic_mysql4>
            <class>Mcmr_Arithmetic_Model_Mysql4</class>
            <entities>
                <arithmetic>
                    <table>newslettersignups</table>
                </arithmetic>
            </entities>
        </arithmetic_mysql4>
    </models>

Answer 1

There is not an easy way to do that.

The best solution would be to extend the configuration file :

<models>
    <arithmetic>
        <class>Mcmr_Arithmetic_Model</class>
        <resourceModel>arithmetic_mysql4</resourceModel>
    </arithmetic>
    <arithmetic_mysql4>
        <class>Mcmr_Arithmetic_Model_Mysql4</class>
        <entities>
            <arithmetic>
                <ignore_prefix>1</ignore_prefix>
                <table>newslettersignups</table>
            </arithmetic>
        </entities>
    </arithmetic_mysql4>
</models>

Then you could override the getTableName method of Mage_Core_Model_Resource class to make it consider the additional config attribute "ignore_prefix" for the entity.

if ($mappedTableName) {
    $tableName = $mappedTableName;
} else {
    if($entityConfig->ignore_prefix)
        $tablePrefix = '';
    else
        $tablePrefix = (string)Mage::getConfig()->getTablePrefix();
    $tableName = $tablePrefix . $tableName;
}