A quick solution would be to change this:
//rename the array keys
foreach( $data as &$new_values ) {
$new_values['user_id'] = $new_values[0]; unset( $new_values[0] );
$new_values['product_id'] = $new_values[1]; unset( $new_values[1] );
}
Into this:
//rename the array keys
foreach( $data as &$new_values ) {
$new_values['user_id'] = (string) $new_values[0]; unset( $new_values[0] );
$new_values['product_id'] = (string) $new_values[1]; unset( $new_values[1] );
}
However, I think you can shorten the work a bit by only looping once. This is based on the your code so I’m just guessing on the structure on the data retrieved from the database.
$wpdb->get_results() has a second parameter which you can use to choose how the retrieved data should be structured. In my code below I use an associative array instead of the default object. This is just a preference for me and does not really matter in this case. But if you would not need your resulting data array to be indexed by the item_id you wouldn’t have to convert your retrieved data from an objects to associative arrays with this parameter.
global $wpdb;
//Retrieve the form entries from the database.
$form_entries = $wpdb->get_results( "SELECT * FROM {$wpdb->prefix}frm_item_metas WHERE field_id in (145,147)", ARRAY_A );
$data = array();
// Loop through all form entries from query and add them to the data array.
foreach ( $form_entries as $form_entry ) {
// Make sure the item_id exist and some kind of meta value too.
if ( ! empty( $form_entry[ 'item_id' ] ) && ! empty( $form_entry[ 'meta_value' ] ) ) {
$item_id = $form_entry[ 'item_id' ];
$entry_value = $form_entry[ 'meta_value' ];
// Begin row in data array with the item_id as the numeric key.
$data[ $item_id ] = array();
// Add user_id if it exist.
if ( $entry_value[ 'user_id' ] ) {
$data[ $item_id ][ 'user_id' ] (string) $entry_value[ 'user_id' ];
}
// Add product_id if it exist.
if ( $entry_value[ 'product_id' ] ) {
$data[ $item_id ][ 'product_id' ] (string) $entry_value[ 'product_id' ];
}
}
}
// $data should now hold the structure as you described
/*
//rename the array keys
foreach( $data as &$new_values ) {
$new_values['user_id'] = $new_values[0]; unset( $new_values[0] );
$new_values['product_id'] = $new_values[1]; unset( $new_values[1] );
}
unset($new_values);
*/
You might want to read up a bit about protecting queries against SQL injection attacks. Unless those two field_ids are static.