[Dbix-class] Problems getting prefetch to work..

[Alex Beamish]

On 6/24/06, Tim Watson <tiwatson at gmail.com> wrote:
>
> I am probably missing something simple here, but I can't see it.
>
> I am having trouble getting any prefetching to work, in my own code or
> in the example code linked here:
>
>
> http://search.cpan.org/~jrobinson/DBIx-Class-0.06003/lib/DBIx/Class/Manual/Example.pod
>
> With the example, only changing the DB type to be mysql and my
> login...   I get an sql error, the JOIN section is not working
> properly....
>
> SELECT me.trackid, me.cd, me.title, cd.cdid, cd.artist, cd.title
> FROM track me  JOIN cd cd ON ( cd.cdid = me.cd )
> WHERE ( cd.title = ? )
>
> In my own code... equally as simple..
>
> -----------
> package Db::Schema::User;
>
> use strict;
>
> use base qw/DBIx::Class/;
>
> __PACKAGE__->load_components(qw/PK::Auto Core/); # for example
> __PACKAGE__->table('user');
> __PACKAGE__->add_columns(qw/ username password /);
> __PACKAGE__->set_primary_key('username');
> __PACKAGE__->has_many(user_session => 'Db::Schema::Session', 'username');
>
> ----------------
>
> package Db::Schema::Session;
>
> use strict;
>
> use base qw/DBIx::Class/;
>
> __PACKAGE__->load_components(qw/PK::Auto Core/); # for example
> __PACKAGE__->table('session');
> __PACKAGE__->add_columns(qw/sessionid username /);
> __PACKAGE__->set_primary_key('sessionid');
> __PACKAGE__->belongs_to(username => 'Db::Schema::User');
>
>
> -----------------
>
>
> my $rs = $dbh->resultset('Session')->search({ 'session.sessionid' =>
> '123456' } ,{ prefetch => 'username' });
> my $session = $rs->next;
> print "s " . $session->sessionid . "\n";
>
> (prefetching on anything but username gives me a relationship error)


Did you try prefetching on user_session?

I've been having problems with this part of the package as well, and I'm
still working on how to improve this part of the documentation.

In my mind, the naming goes from Database Tables -> Relationships (has_many,
and so forth) -> ResultSet calls. In the POD, the database table called 'cd'
has a relationship called 'tracks' that refers to the 'track' table, for
example, which explains why the resultset call uses 'tracks' and not
'track'.

Now, that's not carved in stone -- I still need to make a few more visits
through the code using the debugger, to get it all figured out, but that's
what I've found out so far, and I'm eager to share more knowledge.

Good luck.

--------
>
> SELECT me.sessionid, me.username, username.username, username.password
> FROM session me  JOIN user username ON ( username.username =
> me.username ) WHERE ( session.sessionid = ? )'
>
> I get the same JOIN errors...   Any idea what I am doing wrong ??
>
> --
> Tim Watson
>
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>



-- 
Alex Beamish
Toronto, Ontario
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