Add contains files to Hydra::PCDM::Interfaces::Object

[carolyncole]

Hydra::PCDM::Interfaces::Object (this is a module)
Should be able to contains pcdm:File using the pcdm:hasFile (eg Hydra::PCDM::GenericFile)

• The files should live at a sub uri of the pcdm:Object (This is AF::Base contains)
• There should be a pcdm:has_file assertion on the object that points at the file (This is AF::Base:has_and_belongs_to_many)
• This task should figure out how to combine the behaviors above
• There can be zero to many files
• the path to the file subnode can be auto generated

[awead]

I don't know if has_and_belongs_to_many implements LDP direct containment.

[flyingzumwalt]

Is this a repetition of #23?

[awead]

@flyingzumwalt it's tangentally related, but probably pertains more to what @elrayle is doing with the finishing the modeling.

[jcoyne]

Do we need to have more than?

        contains "content", class_name: 'FileContentDatastream'
        contains "thumbnail"

[awead]

@jcoyne if that does the /files direct container URI to do the containment, then no.

[jcoyne]

Hmmm, yeah, it also doesn't set hasFile, just ldp:contains.

[awead]

@jcoyne right. can we do something like aggregates :files ? But that creates in indirect container. The examples I'm seeing have /files as a direct container.

[elrayle]

My first instinct is to say, avoid aggregates since the model discussions I've been in have not treated files as an aggregation. Issues and questions...

• Is contains a concept that is already solidly in Fedora? Is there a method that gets called to add files to the contains relationship? (similar to aggregates for hasMembers)
• Do we ever want order to the list of files? NOTE: order will be tricky because GenericFiles which contains Files already has an ordered aggregation. Since the PCDM::Object can have only one aggregation with a head (IANA.first), we can't have two separate ordered aggregations for the same subject (the PCDM::Object).

[awead]

@elrayle contains translates to a ldp basic container. For files, we need the hasFile predicate, and therefore a ldp direct container. I don't believe the PCDM model allows for ordering at the hasFile level, so we should be safe there.