OpenWGA 7.9 - OpenWGA Concepts and Features

Content Stores » Structure » Other data

Extension data fields

Extension data fields are new since content store version 5. These are key/value pairs, similar to items on content documents, able to store arbitrary data.

However unless items extension data fields are attacheable to many entities in OpenWGA:

  • Documents of all types
  • Individual file attachments on content documents and file containers
  • The content store database itself (frequently called "database metadata")

Extension data fields are mainly an internal feature used by OpenWGA to extend the data storable on an entity without changing the schema of the underlying database. Many metadata fields on documents are actually stored as extension data fields "in the background".

That said it however is possible to use extension data fields in custom design programming, provided that the used extension data names do not collide with those used by OpenWGA internally. This should be ensured by qualifying those names with an underscore as prefix "_", maybe extended with some additional qualifier identifying the design that uses it.

Extension data fields are settable and readable by WGAPI only. The interface WGExtensionDataContainer is provided on every WGAPI object which is cabable of storing extension data fields:

  • On all WGDocument objects. Extension data fields are persisted on calling the save() method of the document
  • On WGFileMetaData. Extension data fields are persisted on calling the save() method of the document which carries the file attachment
  • On WGDatabase. Modifications to extension data fields are immediately persisted.