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Turn the AC on

A large part of Wikidata is the collection of external identifiers for items. For some item types, such as items about people (Q5), some of this is what is known as Authority Control (AC) data, for example, VIAF (P214). One thing that distinguishes AC data from other external IDs is that AC data sources are often available in machine-readable form. This can be used for Wikidata in several ways:

  • to add new statements (eg occupation or birth place of a person)
  • to add new references to existing statements
  • to find and add more AC identifiers

Over the years, I wrote several bespoke tools and scripts that would query one of these AC websites, and add bits and pieces to Wikidata items, but I always wanted a more unified solution. So I finally got around to it and wrote a new tool on Toolforge, AC2WD. This presents an API to:

  • query multiple AC sources via an ID
  • create new Wikidata items (in memory, not on Wikidata!) from each source
  • merge several such “virtual” items into one (the sum of all AC data knowledge)
  • construct a “diff”, a JSON structure containing instructions to add new information (statements, references) to an existing Wikidata item

By giving an existing Wikidata item ID to this API, it will extract existing AC identifiers from the item, and load information from the respective AC sources. It will then check the new information for new, usable AC identifiers, and repeat. Once all possible AC data has been loaded, it will return the “diff” data to extend the item with the new information (via ), using the wbeditentity action of the Wikidata API.

Now this is all very technical for most users, so I wrote a little JavaScript utility for Wikidata, rather predictably also called AC2WD (usage instructions on the page). Any Wikidata item with at least one supported AC property will have an “AC2WD” link in the tool sidebar. If you click on it, it will fetch the “diff” from the Toolforge tool, and attempt to make an edit to add new information (reload the page to see it, or check out the history to see the changes in detail).

I am happy to extend the API to support new AC sources (that have a Wikidata property!), please let me know your favourite candidates. I may also be able to extract more information from certain AC sources than I currently do; again, please let me know if you have a preference.