[Dbix-class] Second join gets eaten in _merge_attr

[Zbigniew Lukasiak]

On 10/29/07, brett gardner <brett at clientcomm.com.au> wrote:
> I don't think its as simple as that.
>
> I recently had to implement this behaviour and realised that in some
> cases you might need to rename the columns in the query. eg
>
> $rs->search({'foo.bar_id' => 2},{join=>'foo'});
>
> then later
>
> my $new_rs = $rs->search({'foo.bar_id' = 45},{join=>'foo'});
>
> which would result in the query
>
> SELECT ....
> FROM tbl1 LEFT JOIN foo ON (...)
> LEFT JOIN foo foo2 ON (...)
> WHERE
> foo.bar_id = 2 AND foo.bar_id = 45
>
> Which is incorrect. as the second search clause should be "foo2.bar_id =
> 45".
>
> Because the code may not be aware of how many times "foo" has been
> joined already the resultset needs to rename the search fields in the
> search method.

So you have two cases -

1. The one that is covered by the current code is when you need to
search by a field in a table that is already joined

2. The case that you have where you need to really join the table second time

When you use second time the same field it obviously can be only the
case 2 - but in general I cannot see any way to discriminate between
those two cases.

I have something like the case 2 - because I need to join a table
multiple times. With the patch from luke I can do this at least
manually, but it would be nice the renaming of parameters was done
automatically.

-- 
Zbigniew Lukasiak
http://perlalchemy.blogspot.com/