I have a Catalyst action which (simplified) does something along the
lines of:
# $obj->id is the sole primary column, type int, auto increment
my $obj = $rs->create( $c->request->parameters );
When editing an existing record (e.g. $c->request->parameters == { id =>
1, name => 'existing_record' }), the record is updated and a call to
$obj->id returns "1" in this case.
When creating a new record, e.g. $c->request->parameters == ({ id => '',
name => 'new_record' }), a new record is added to the database, but the
call to $obj->id returns an empty string rather than the new primary key
value.
The reason is that DBIx::Class::PK::Auto::insert() appears not to
retrieve the last insert id if supplied with anything other than undef
for one or more primary key columns. In this case "id" contains an empty
string, so PK::Auto does not try to look up the new value.
The workaround is trivial, i.e. manually delete empty string from any
request parameter corresponding to an auto incrementing column, but I
have a couple of thoughts.
Firstly, assuming this behaviour is as intended (for efficiency?), I
think it's probably worth a mention in the Cookbook because it tripped
me up and will doubtless trip others up in future.
Secondly, it also trips up
DBIx::Class::HTMLWidget::populate_from_widget(), so perhaps that module
needs a workaround.
Thirdly, I'm wondering if PK::Auto is doing the sane thing here.
Technically I suppose it's doing the *right* thing, because a primary
key column *could* contain an empty string. But in general a primary key
containing an auto incrementing column usually contains *only* a single
auto incrementing column of type int or similar. If you're using
PK::Auto, chances are your primary key is a single auto-incrementing
column and an empty string would not be a valid value. Consequently I
think it might make sense if PK::Auto::insert() were to treat an empty
string in the same way as undef when deciding whether to fetch last
insert id from the database. I'd have thought the convenience of having
primary key values returned correctly every time would far outweigh the
small performance hit it might incur in a small percentage of cases.
Any thoughts?
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