Joomla Mysql query in foreach loop - php

Question

I'm trying to build a simple select list in Joomla 2.5 with php and mysql, but I've got a problem: it doesen't load the options name... are there any error?
<?php
$db = JFactory::getDBO();
$query = $db->getQuery(true);
$query->select('optValue');
$query->from('#__sobipro_field_option');
$query->where("fid='38'");
$db->setQuery((string)$query);
$results = $db->loadObjectList();
if ($results){
echo "<select>";
foreach($results as $result){
foreach($result as $value) {
$query->select('sValue');
$query->from('#__sobipro_language');
$query->where("fid='38' and language='it-IT' and sKey='".$value."'");
$db->setQuery((string)$query);
$name = $db->loadResult();
echo "<option value=\"$value\">".$name."</option>";
}
}
echo "</select>";
}
else {
echo 'Error';
}
?>

Answer 1

Whenever you're trying to debug Joomla! code turn on debug mode (Global Configuration->System->Debug Settings) and turn Error Reporting up to Development (Global Configuration->Server->Error Reporting), then you would have seen your problem straight away.
$query is a actually an object of type JDatabaseQuery and should be used as is in the $db->setQuery($query) call without casting to a (string).
When referencing a database, table or column name it's a good idea to use Joomla's mechanism for wrapping the name is the correct quotes e.g.
$query-select($db->quoteName('optValue'))
Amongst other things this will insure that SQL keywords aren't a problem.
Likewise for values, use the Joomla! provided $db->quote() method. e.g.
$query->where($db->quoteName('fid') . '=' . $db->quote('38'));
When building a WHERE query with multiple values ANDed together you can simply add each item as it's own ->where() clause.
So your where before I would tend to write as:
$query->where($db->quoteName('fid') . '=' . $db->quote('38'));
$query->where($db->quoteName('language') . '=' . $db->quote('it-IT'));
$query->where($db->quoteName('sKey') . '=' . $db->quote($value));
Finally, as you've said both of your $queries work by themselves, but when put together in your code as shown they don't.
The reason for this is that after you configure $query for your first statement (and run it), you continue to add to the second statement to the original $query object. So, that when you do the second, third etc setQuery($query) the SQL is getting longer and longer and unlikely to return any results.
As you don't test for success of each $db->loadResult() in the inner-most foreach loop you never see the error.
At the very least you need to add a new $db->getQuery(true) at the beginning of your inner loop, like this:
<?php
// Get default database object
$db = JFactory::getDBO();
// Get a new JDatabaseQuery object
$query = $db->getQuery(true);
// Build the query
$query->select($db->quoteName('optValue'));
$query->from($db->quoteName('#__sobipro_field_option'));
$query->where($db->quoteName('fid') .'=' . $db->quote('38'));
// Set the query for the DB oject to execute
$db->setQuery($query);
// Get the DB object to load the results as a list of objects
$results = $db->loadObjectList();
if ($results){
echo "<select>";
foreach($results as $result)
{
foreach($result as $value)
{
// Get a new query object
$query = $db->getQuery(true);
// Build the query
$query->select($db->quoteName('sValue'));
$query->from($db->quoteName('#__sobipro_language'));
$query->where($db->quoteName('fid') .'=' . $db->quote('38'));
$query->where($db->quoteName('language') .'=' . $db->quote('it-IT'));
$query->where($db->quoteName('sKey') .'=' . $db->quote($value));
$db->setQuery($query);
$name = $db->loadResult();
echo "<option value=\"$value\">$name</option>";
}
}
echo "</select>";
}
else
{
echo 'Error';
}
This is going to potentially create a lot of objects, so, you should consider if there's a way to restructure it all into one SQL query this will make it significantly faster and reduce the load on your server.