db_select usage in class and returned object

Question

I'd like to use db_select in a static public function of a certain class. The query should be a base query, which may then be customized in the calling function. Returning the result sets seems to work, but I'd like to return the drupal db_select-object for further usage. Here is some example code:

class foo{ 
 public static function get_query() {
  $query = db_select('bar', 'b'); 
  return $query;
 }
} 
function test() { 
  $qobj = foo::get_query(); 
  $qobj->fields('b', array('id', 'name'));
  $result = $qobj->execute();
  ...
}

The returned object seems not to be a db_select object, which can be edited further more. Do I have to create a dummy db_select and pass the reference of this object to the static function.

Thank you.

Sven

Answer 1

There's no such class as db_select, but your code will return a valid SelectQuery.

class foo{ 
 public static function get_query() {
  $query = db_select('bar', 'b'); 
  return $query;
 }
} 
function test() { 
  $qobj = foo::get_query(); 

  // Get type of object
  dpm(get_class($qobj));

  // Alter the query string and make sure it has been altered
  $qobj->fields('b');
  dpm((string) $qobj);

}
test();

The first Devel output for the above is SelectQuery, as expected. The second is the following query string:

SELECT b.*
FROM 
{bar} b

Now add another function to the mix:

function test2() { 
  $qobj = foo::get_query(); 
  $qobj->fields('b', array('x'));
  dpm((string) $qobj);
}

Run that in the same page request, and you get this query string

SELECT b.x AS x
FROM 
{bar} b

So your code works exactly as you've specified that it should do.

If you're expecting something else to happen, it would be a good idea to detail that in the question.