[Dbix-class] Populate and related tables

[Louis Erickson]

I know context can matter, but I would never have expected it to in this case.  I would never have thought to try capturing the return value to change the result.

Does anyone know if that's a deliberate difference or is this an unexpected behavior?

On May 11, 2014, at 9:35 AM, Hailin Hu <i at h2l.name> wrote:

> Hi,
> 
> populate() seems to determine the data structure from the first one in
> the array in void context.
> Although you don't need the return value, you can have a try:
> my $rs = $schema->resultset('Artist')->populate([...
> 
> 
> On Sun, May 11, 2014 at 11:38 AM, Louis Erickson <lerickson at rdwarf.net> wrote:
>> I've been throwing away some old code and replacing it with
>> DeploymentHandler.  All my old hand-written SQL files are being replaced by
>> Perl which uses DBIC to populate the database.
>> 
>> One of those functions to populate the database didn't work right.
>> Eventually, I boiled it down to an standalone test, which still fails in a
>> way I didn't expect.  I'm not sure if I'm doing something wrong, or if I've
>> missed something in the docs, or if there's a lurking bug.
>> 
>> What I'm seeing is that if I call populate() with a data structure where the
>> first item does not reference other tables, none of the other items in the
>> data structure will create items in referenced tables.  If the first item
>> does refer to other tables, all other references will get created as I
>> expected.
>> 
>> My sample has two simple tables:
>> 
>> package TestDb::Schema::Result::Artist;
>> 
>> use Moose;
>> use MooseX::NonMoose;
>> use MooseX::MarkAsMethods autoclean => 1;
>> extends 'DBIx::Class::Core';
>> 
>> __PACKAGE__->table ('artist');
>> 
>> __PACKAGE__->add_columns (
>>  id => {
>>    data_type => 'int',
>>    is_auto_increment => 1,
>>  },
>>  name => {
>>    data_type => 'varchar',
>>  },
>> );
>> 
>> __PACKAGE__->set_primary_key ('id');
>> 
>> __PACKAGE__->has_many (cds => 'TestDb::Schema::Result::CD', 'artist_id');
>> 
>> __PACKAGE__->meta->make_immutable;
>> 
>> 1;
>> 
>> 
>> package TestDb::Schema::Result::CD;
>> 
>> use Moose;
>> use MooseX::NonMoose;
>> use MooseX::MarkAsMethods autoclean => 1;
>> extends 'DBIx::Class::Core';
>> 
>> __PACKAGE__->table ('cd');
>> 
>> __PACKAGE__->add_columns (
>>  id => {
>>    data_type => 'int',
>>    is_auto_increment => 1,
>>  },
>>  title => {
>>    data_type => 'varchar',
>>  },
>>  artist_id => {
>>    data_type => 'int',
>>  },
>> );
>> 
>> __PACKAGE__->set_primary_key ('id');
>> 
>> __PACKAGE__->belongs_to (artist => 'TestDb::Schema::Result::Artist',
>> 'artist_id');
>> 
>> __PACKAGE__->meta->make_immutable;
>> 
>> 1;
>> 
>> 
>> Simple as I could make it.
>> 
>> When I call populate with data like this, everything works:
>> 
>> $schema->resultset('Artist')->populate([
>> {
>> name => 'The Beatles',
>> cds => [
>> { title => "Sgt. Pepper's Lonely Hearts Club Band" },
>> { title => "Yellow Submarine" },
>> { title => "Rubber Soul" },
>> { title => "Meet the Beatles" },
>> ],
>> },
>> {
>> name => 'ABBA',
>> cds => [
>> { title => 'ABBA Gold' },
>> { title => 'More ABBA Gold '},
>> ],
>> },
>> { name => 'Anonymous' },
>> ]);
>> 
>> 
>> This creates an artist called "The Beatles", and CDs called "Sgt. Pepper's
>> Lonely Hearts Club Band", "Yellow Submarine", "Rubber Soul", and "Meet the
>> Beatles", all referring to the right artist_id for the newly-created "The
>> Beatles" artist.  An artist called ABBA is created, as are both of those
>> greatest hits CDs.  An an "Anonymous" artist is created with no CDs.
>> 
>> Perfect!
>> 
>> But, if I move the {name => 'Anonymous}, first, before any of the others,
>> the behavior is quite different.  None of the CDs get created, just the
>> artists.  There's no errors, no complaints, just no entries in the related
>> tables.
>> 
>> Not what I expected.
>> 
>> Can anyone shed some light on this?  Any thoughts are appreciated!
>> 
>> I have full working code if someone wants me to put a tar file somewhere.
>> 
>> 
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> 
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