[Dbix-class] Values populated by the backend - how to pull?

James FitzGibbon jfitzgibbon at primustel.ca
Thu Dec 15 17:29:25 CET 2005


I looked at that: the code in PK::Auto::Oracle is designed to identify
(based upon a regex scan of the trigger body attached to INSERT on the
table) the name of the sequence that DBIC should pull from in order to
populate the primary key before performing an INSERT.

But as my message stated, our policy does not allow for the client layer to
provide the ID.  The trigger body looks like this:

CREATE OR REPLACE TRIGGER
    foo_seq_trig
BEFORE INSERT ON
    foo
FOR EACH ROW
BEGIN
    IF( :new.id IS NOT NULL ) THEN
        raise_application_error(
            -20001,
            'foo.id is generated for you'
        );
    END IF;
    SELECT main_seq.NEXTVAL INTO :new.id FROM DUAL;
END;
/

Any thoughts given that clarification?

-----Original Message-----
From: dbix-class-bounces at lists.rawmode.org
[mailto:dbix-class-bounces at lists.rawmode.org] On Behalf Of Hartmaier
Alexander
Sent: Thursday, December 15, 2005 4:48 AM
To: dbix-class at lists.rawmode.org
Subject: RE: [Dbix-class] Values populated by the backend - how to pull?

Hi and welcome to DBIC ;-)

You need to load PK::Auto::Oracle in your table classes:

use base qw/DBIx::Class/;
__PACKAGE__->load_components(qw/PK::Auto::Oracle Core/);

I do this in a Parent::All class i use base for all my table classes to make
shared things easier to change.

Also you have to use trunk from svn till the next DBIC version comes out
because I've fixed a PK::Auto::Oracle bug yesterday.

-Alex


-----Original Message-----
From: dbix-class-bounces at lists.rawmode.org
[mailto:dbix-class-bounces at lists.rawmode.org] On Behalf Of James FitzGibbon
Sent: Wednesday, December 14, 2005 9:42 PM
To: dbix-class at lists.rawmode.org
Subject: [Dbix-class] Values populated by the backend - how to pull?

I'm relatively new to DBIC, so hopefully there is a simple answer for this.

Given the following two classes:

package Foo;
__PACKAGE__->primary_key( 'id' );
__PACKAGE__->has_many( bars => 'Bar' => 'foo_id' );

package Bar;
__PACKAGE__->belongs_to( foo => 'Foo' => { 'foreign.id' => 'self.foo_id' }

And the following (truncated) table DDL:

CREATE TABLE foo (
	id NUMERIC(10) NOT NULL PRIMARY KEY,
);

CREATE TABLE bar (
	id NUMERIC(10) NOT NULL PRIMARY KEY,
	foo_id NUMERIC(10) NOT NULL,
	bar NUMERIC(10) NOT NULL,
	CONSTRAINT
		bar_foo_id_fk
	FOREIGN KEY(foo_id)
	REFERENCES
		foo(id)
);

The id column on the tables is populated from a sequence *by a trigger*, not
by DBIC.

I can create a Foo object without providing any attributes, because of the
trigger and default values.  If I then try to do this:

$foo = Foo->create;
$foo->add_to_bars( { bar => 1 } );

It fails with an error like this:

DBD::Oracle::st execute failed: ORA-01400: cannot insert NULL into
("BAR"."BAR_AUDIT"."FOO_ID")

This particular error is from my audit trigger, but the underlying cause is
that the Foo object I created does not have it's id field populated.  When
Bar->create_related is called, it realizes that the foo_id attribute needs
to have the value of Foo->id.  Because the value of id is only in the
database and not in the object, it's trying to populate a Bar object whose
foo_id attribute has an undef value.

My first guess is that I need to invalidate the in-memory version of the Foo
object so that when Foo->get_column('id') is called, the value from the
sequence is pulled from the database.  But there doesn't seem to be any
query code in DBIC::Row.  It's all in DBIC::Table.

Except ... I can't even use search() to discard the $foo object I have and
replace it with one borne of the database, because the in-memory $foo object
has no identifying attributes that I can use as criteria to search() or
search_like().

Am I being dumb here?  Local policy requires that the sequence values are
assigned by the database (as in "if you try to provide your own id value,
the trigger will throw an exception"), so I can't have DBIC grab the next
sequence value (which I assume would solve this problem).

I notice that that docs for DBIC::Row->get_column() say "Currently, does not
do any queries;" - is this just a shortcoming in the early DBIC releases
that at some point will be fixed?

Thanks

-- 
j.
 
James FitzGibbon
Systems Developer, Primus Telecommunications Canada Inc.
416.644.6111

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