[Dbix-class] role of result class?

[Jess Robinson]

On Tue, 7 Mar 2006, Richard Jolly wrote:

> Hi,
>
> I'm trying to understand the role of the result_class, and I have what
> I think are naive questions.
>
> In a schema with
>
>   My::Schema::Artist
>
>   ...
>
>   my $schema->resultset('Artist')->search();
>   My::Artist->search();
>
> Are the last two lines identical? Why is the first the preferred syntax?

Whether those two are identical or not, depends on how you connected, if 
you just do;

My::Schema->connection('dbi:Foo' .. );

Then there is just one global connection, and you can call search on your 
class names, if however you  use:

my $schema = My::Schema->compose_connection, or ->connect,

then the information about the connecion/DB is stored in the $schema 
object (in $schema->storage), and My::Artist->search will not work at all.

> Secondly, when over riding resultset methods for a specific class I
> believe the new methods get defined in My::Schema::Artist. But you
> could put them in My::Artist as well, and they would just sit slightly
> higher up the MRO. Does anyone actually put methods in the result class
> file?

No, adding methods to My::Schema::Artist or My::Artist will only make them 
available to Row objects (DBIx::Class::Row).

The difference is this:, If you run a search in scalar context, what you 
get is a ResultSet object, which will not have any of the methods you put 
in your individual table classes (My::Artist etc.), but does have 
convenience methods like ->count (how many items were returned) and so on. 
Calling ->next on that result set, or calling search in list context, will 
get you Row objects, which will each represent a row of the result, and 
will be inherited from your My::Artist/table classes, and thus inherit 
those methods.

So if you want to add methods to a search result as a whole, you need to 
create your own result_class ..

I hope that makes sense,

Jess