[Dbix-class] RFC - has_subset

[Moritz Onken]

A boolean method which tells if arow is in a subset:

$row->is_output
$row->is_input

$row->subset (returns input or output)

Am 31.03.2008 um 13:45 schrieb Daniel Ruoso:
> Hi,
>
> I'm working on an application that have the following classes:
>
>  TaskType --- has_many ---> TaskTypeFile
>
> but, that can actually be seen as two relationship types:
>
>          ____ has_many { type => input } __
>         /                                  \
>  TaskType                            TaskTypeFile
>         \____ has_many { type => output }__/
>
> Or, this could be seen as:
>
>                                TaskTypeFile
>                               /\          /\
>                                |          |
>                               is          is
>                                |          |
>                           InputFile     OutputFile
>           _______ has_many__/            |
>          /                               |
>  TaskType --------------- has_many ------/
>
> But one could see InputFile and OutputFile simply as a subset of
> TaskTypeFile, and once this is done, we can keep the simplicity of
> the first diagram, and filter on the TaskTypeFile as needed, which  
> also
> enables the input/output view independent on the TaskType  
> relationship.
>
> So, instead of doing
>
> $tasktypers->input_files
> $tasktypers->output_files
>
> I could do
>
> $tasktypers->files->input
> $tasktypers->files->output
>
> The major difference in that is that I can do
>
> my $rs = TaskType->find($id, { prefetch => 'files' });
> while ($rs->files->input) {...}
> while ($rs->files->output) {...}
>
> With a single query, as the input/output resultset would simply
> implement a filter on the previous resultset, while
>
> TaskTypeFile->input->search({ name => 'foo.txt' });
>
> would still be possible.
>
> So, the proposed interface is:
>
> __PACKAGE__->load_components( ... Subset ... );
> ...
> __PACKAGE__->has_subset('input', { type => 'input' });
> __PACKAGE__->has_subset('output', { type => 'output' });
>
> It would add that as a part of the where clause when no cache is
> present, and grep on the cache when already prefetched...
>
> I still didn't go through the coding, so, this is the time for any
> comments or tomatoes...
>
> daniel
>
>
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