What is the purpose of the method getTable()?

Question

I have a question about the SetupInterface method getTable($tableName).

What is its role? Why should I use this method instead of using directly the name of the table I want to work on?

Is it in case I need to work on differents databases?

Answer 1

Is it in case I need to work on differents databases?

Definitely not

What is its role? Why should I use this method instead of using directly the name of the table I want to work on?

The reason is because Magento supports table prefixes out of the box. This is the main purpose of this method, as if you work on a database with table prefixes then calling the original table name directly will break your code.

FYI, here's the implementation of that method:

public function getTable($tableName, $connectionName = ResourceConnection::DEFAULT_CONNECTION)
{
    $cacheKey = $this->_getTableCacheName($tableName);
    if (!isset($this->tables[$cacheKey])) {
        $this->tables[$cacheKey] = $this->resourceModel->getTableName($tableName, $connectionName);
    }
    return $this->tables[$cacheKey];
}

And if you check the getTableName from the resource model:

public function getTableName($modelEntity, $connectionName = self::DEFAULT_CONNECTION)
{
    $tableSuffix = null;
    if (is_array($modelEntity)) {
        list($modelEntity, $tableSuffix) = $modelEntity;
    }

    $tableName = $modelEntity;

    $mappedTableName = $this->getMappedTableName($tableName);
    if ($mappedTableName) {
        $tableName = $mappedTableName;
    } else {
        $tablePrefix = $this->getTablePrefix();
        if ($tablePrefix && strpos($tableName, $tablePrefix) !== 0) {
            $tableName = $tablePrefix . $tableName;
        }
    }

    if ($tableSuffix) {
        $tableName .= '_' . $tableSuffix;
    }
    return $this->getConnection($connectionName)->getTableName($tableName);
}