[Dbix-class] joining on NULL fields

[Matt S Trout]

On Mon, Mar 17, 2008 at 08:02:42PM +0000, Ian Sillitoe wrote:
> There might be a really simple answer to this, but I'm afraid I can't see it
> - I would really appreciate any help.
> 
> I'm trying to describe a number of relationships between two tables that
> require 0 or more conditions on the join to be NULL - e.g.
> 
> MySchema->('Domain')->search(
>  { domain_id => 'd1' },
>  {
>    join     => [ qw/ domain_to_classification_depth_(1-4) / ],
>    prefetch => [ qw/ domain_to_classification_depth_(1-4) / ]
>  }
> )
> 
> Where the relationships are defined as:
> 
> MySchema::Domain->belongs_to(
>   "domain_to_classification_depth_4",
>   "MySchema::Classification",
>   {
>     "foreign.depth_1" => "self.depth_1",
>     "foreign.depth_2" => "self.depth_2",
>     "foreign.depth_3" => "self.depth_3",
>     "foreign.depth_4" => "self.depth_4",
>   },
> );
> 
> [WORKS]
> 
> MySchema::Domain->belongs_to(
>   "domain_to_classification_depth_2",
>   "MySchema::Classification",
>   {
>     "foreign.depth_1" => "self.depth_1",
>     "foreign.depth_2" => "self.depth_2",
>     "foreign.depth_3" => \"NULL",
>     "foreign.depth_4" => \"NULL",
>   },
> );

There's not currently a way to do that without using a custom from => attr
to your resultset.

Proposed syntax + patches welcome :)

-- 
      Matt S Trout       Need help with your Catalyst or DBIx::Class project?
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