Accessing data from another database in Joomla 3.2+ - php

Question

I am upgrading my components from Joomla 1.7 to Joomla 3.3 and have to keep the original database. Therefore I need to access the display data from another database as the installation database. I tried a method that I used many times before with Joomla 2.5 but it seems that I cannot get it right this time.
In my model in the getListQuery() method (which overrides the modellist method) I use the following code to access the database from where I want to get my data:
$dbOptions = getDbOptions();
$db = & JDatabase::getInstance($dbOptions);
where the connection details of my old database are contain in $dbOptions.
I continue to use the following code:
$query = $db -> getQuery(true);
$query -> select('*') -> from('table');
return $query;
I do include the following in the beginning:
jimport('joomla.application.component.modellist');
modellist extends JModelLegacy, therefore I do believe that it uses the following:
/libraries/legacy/model/list.php
But it gives me an error that the table newDatabase.table does not exits and therefore the method I am using does not connect to my old database to retrieve the data from oldDatabase.table.
I am unsure about the inclusion of jimport('joomla.application.component.modellist'); though, could be the problem?
Anyone who can help to retrieve the data from my original database?

Answer 1

If old database on same server and active mysql user has access for it you can use such sql query:
$query = $db -> getQuery(true);
$query -> select('*') -> from('old_database.table');
return $query;

Answer 2

If the entire model is just fetching data from the external database you could use JDatabase->setDbo to replace the default database object with your custom one.
public function __construct($config = array())
{
parent::__construct($config);
$options = array();
$options['driver'] = 'mysqli';
$options['host'] = 'localhost';
$options['user'] = 'username';
$options['password'] = 'password';
$options['database'] = 'database';
$options['prefix'] = 'jos_';
$db = JDatabase::getInstance( $options );
parent::setDbo($db);
}
Now you should be able to access the database in getListQuery() just as you would with your default database. E.g.
$db = JFactory::getDbo();

Answer 3

I believe Adam B's code can have some improvement, regarding setting DB.
public function __construct($config = array())
{
$options = array(
'driver' => 'mysqli',
'host' => 'localhost',
'user' => 'username',
'password' => 'password',
'database' => 'database',
'prefix' => 'jos_'
);
//parent construct will handle setting the DB
$config['dbo']=JDatabase::getInstance( $options );
parent::__construct($config);
}
And getting DB: I think JFactory::getDbo(); will give you the wrong DB, you should do:
self:getDbo();

Answer 4

Using Joomla 2.5, this approach worked for me:
$option = array();
$option['driver'] = 'mysql';
$option['host'] = 'localhost';
$option['user'] = 'XXXXXXXX';
$option['password'] = 'XXXXXXXX';
$option['database'] = 'wordpress';
$option['prefix'] = 'jtt_';
$db = JDatabase::getInstance( $option );
$query = "select * from #__categories";
$db->setQuery($query);
I was able to connect to another database just fine.