Making Attribute Items Resource Components

Currently attribute::Item is not considered a component to an Attribute Resource (only attribute::Attribute is derived from resource::Component). This topic is focused on presenting potential benefits of changing the design as well as attempting to scope out what code changes this would entail.

Potential Benefits

  • Items could be specified/returned w/r Operations
  • Reference Items would be explicitly specified in a Resource Link making lookup and conflict resolution easier
  • Items could have properties
  • Items could be targeted by Reference Items
  • Items could be found by UUID
  • In the case of supporting active categories, if the resource has a map of all items it could easily traverse it to activate/deactivate Reference Items based on categories.

Potential Coding Tasks

Resource Link Usage Changes

  • All of the current code that deals with Resources Links at the Attribute Level would need to be pushed down to the Reference Item Level. This could in theory make things cleaner since right now Reference Item has to manipulate the links through its Attribute.

Attribute Resource Changes

  • Need to update Query grammar to include Items and their types (and values??)
  • Probably needs to have a map of UUIDS to Items
  • Deleting Items will now involve the resource
  • Items will have direct access to the resource instead of having to go through its attribute/parent item

Additional I/O support (XML and JSON)

  • Need to store properties on the Items - This is probably easy for JSON since the property system already supports this. Not too sure about XML.
  • Need to store the UUID (not too much of an issue though the XML form probably needs to support the case of Items w/o UUIDs - when attributes are being hand written)
  • Probably don’t need to change the format version

Attribute Utility Changes

  • Find associatable objects will need to include items

QT GUI Changes

  • qtReference Item will probably need some slight changes.

@chart3388 @amuhsin @johnt @dcthomp - FYI

Adding properties to Item instances will work as soon as Item inherits Component. As long as smtk::attribute::to_json(json&, const ResourcePtr&) and smtk::attribute::from_json(const json&, ResourcePtr&) call smtk::resource::to_json(json&, const ResourcePtr&) and smtk::resource::from_json(const json&, ResourcePtr&) in their respective implementations, JSON serialization/deserialization will just work.

Because XML is treated as “import/export” format instead of the native format, it might be acceptable to omit properties when exporting XML – at least initially – since exporting can be a lossy process.

Can an item be associated to itself? Assume so since an attribute resource can be.

I assume auto-association is about as possible and useful as auto-cannibalism… nothing’s really stopping you, but why?

No use case other than testing pandora’s box.

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