index is not visible to DBIx::Class - perl

Question

I have this small perl code which is going to add a record to a table but I am confused why DBIC is not able to see the primary key?
I am not able to find any answer anywhere. First the names of table and columns were camelCase, which I then changed to underscore but it just won't run :(
$ ./test.pl
DBIx::Class::ResultSource::unique_constraint_columns(): Unknown unique constraint node_id on 'node' at ./test.pl line 80
code:
sub addNode
{
my $node = shift; my $lcNode = lc($node);
my $id = $schema
->resultset('Node')
->find_or_create
(
{ node_name => $lcNode },
{ key => 'node_id' }
);
return $id;
}
table details:
mysql> desc node;
+------------+-----------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+-----------------------+------+-----+---------+----------------+
| node_id | mediumint(5) unsigned | NO | PRI | NULL | auto_increment |
| node_name | varchar(50) | NO | | NULL | |
| node_notes | varchar(1000) | YES | | NULL | |
+------------+-----------------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
DBIx::Class::Resultset:
$ cat Node.pm
use utf8;
package Testdb::Schema::Result::Node;
# Created by DBIx::Class::Schema::Loader
# DO NOT MODIFY THE FIRST PART OF THIS FILE
use strict;
use warnings;
use base 'DBIx::Class::Core';
__PACKAGE__->table("node");
__PACKAGE__->add_columns(
"node_id",
{
data_type => "mediumint",
extra => { unsigned => 1 },
is_auto_increment => 1,
is_nullable => 0,
},
"node_name",
{ data_type => "varchar", is_nullable => 0, size => 50 },
"node_notes",
{ data_type => "varchar", is_nullable => 1, size => 1000 },
);
__PACKAGE__->set_primary_key("node_id");
# Created by DBIx::Class::Schema::Loader v0.07045 # 2017-08-21 22:14:58
# DO NOT MODIFY THIS OR ANYTHING ABOVE! md5sum:bWXf98hpLJgNBU93aaRYkQ
# You can replace this text with custom code or comments, and it will be preserved on regeneration
1;

Answer 1

https://metacpan.org/pod/DBIx::Class::ResultSet#find:
To aid with preparing the correct query for the storage you may supply the key attribute, which is the name of a unique constraint (the unique constraint corresponding to the primary columns is always named primary).
(Emphasis mine.)
In other words, to use the primary key, you need to specify { key => 'primary' }. Any other key attribute is looked up as the name of an additional unique constraint.

Answer 2

You didn't make clear how addNode should work exactly. But if you want to lookup existing nodes by node_name, you should simply remove the key attribute:
my $id = $schema->resultset('Node')->find_or_create(
{ node_name => $lcNode }
);
But read the caveat in the DBIC documentation:
If no such constraint is found, find currently defaults to a simple search->(\%column_values) which may or may not do what you expect. Note that this fallback behavior may be deprecated in further versions. If you need to search with arbitrary conditions - use "search". If the query resulting from this fallback produces more than one row, a warning to the effect is issued, though only the first row is constructed and returned as $result_object.
You should probably consider adding a unique constraint to node_name.

Answer 3

The real ans which came in DBIx list from Henry, is, whatever key you use, the col it corresponds to, should be in the query. all of above are ambiguous, they are not wrong, but they do not clarify the precise fact.