[support] DBTNG Confusion

[Jamie Holly]

Doing a join doesn't return the query interface, but rather the alias 
that was assigned to the joined table. Since variable assignment is 
processed left to right once it processes the ::join method your $users 
variable now contains the table alias.

What you want to do is stop your chaining before any methods that don't 
return the SelectQuery object you are building:

$query = db_select('user_badges_user', 'ubu')
         ->fields('u', array('uid', 'name'))
         ->condition('ubu.bid', $badge->bid); // Up to here you get a 
SelectQueryInterface returned and assigned to query
$query->join('users', 'u', 'u.uid = ubu.uid'); // Calls the join method 
on $query, but doesn't assign the return;
$users = $query->execute(); // Returns the DatabaseStatementInterface 
that you pull your results from

Generally I try to add joins at the beginning of the construction. It 
seems to make it easier to read (it seems most of Drupal's core code 
does the same), so I would write this query like this:

$query = db_select('user_badges_user', 'ubu');
$query->join('users', 'u', 'u.uid = ubu.uid');
$query->fields('u', array('uid', 'name'))
             ->condition('ubu.bid', $badge->bid);
$users = $query->execute();

You could assign $users when you add the fields and conditions, but this 
does make it easier if you want to add anything else to the query down 
the road.

Easiest thing to remember is that if you get a non-member/non-object 
error, then the item right above that doesn't return the proper class 
and you should stop variable assignment there and instead just call the 
method without assignment (ie: $query->join('users', 'u', 'u.uid = 
ubu.uid')).

Chaining might look a little better and save a few keystrokes,  but it 
really doesn't bring any performance enhancements and can keep headaches 
to a minimum, especially when working on classes you aren't that 
familiar with.


Jamie Holly
http://www.intoxination.net
http://www.hollyit.net


On 10/25/2011 1:48 PM, Ms. Nancy Wichmann wrote:
> Using the Boombatower conversion tool, my query comes out to:
>       $users = db_select('user_badges_user', 'ubu')
>         ->fields('u', array('uid', 'name'))
>         ->condition('ubu.bid', $badge->bid)
>         ->join('users', 'u', 'u.uid = ubu.uid')
>         ->execute();
>
> But when I run this, I get:
> *Fatal error*: Call to a member function execute() on a non-object
>
> Joins are getting to be a major pain in the derriere.
>
> Trying this also fails with the same message:
>       $users = db_select('user_badges_user', 'ubu')
>         ->fields('u', array('uid', 'name'))
>         ->condition('ubu.bid', $badge->bid)
>         ->join('users', 'u', 'u.uid = ubu.uid');
>       $users->execute();
>
> ------------------------------------------------------------------------------------------------------------
> And does anyone know why I so rarely get answers to my questions on 
> this list?
> /*Nancy*/
> Injustice anywhere is a threat to justice everywhere. -- Dr. Martin L. 
> King, Jr.
>
>
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