On 26/09/2018 10:16, Andra Waagmeester wrote:
> On Wed, Sep 26, 2018 at 9:47 AM James Heald <jpm.heald@gmail.com> wrote:
>
>>
>> Far better to have a dedicated external-id property for schema.org,
>> which would avoid this; and if there are important concepts there that
>> we don't have an item for on Wikidata, then create those items.
>>
>>
> Creating a dedicated property for schema.org, would also imply the need for
> creating designated properties for other context providers such as OBO,
> SIO, etc. I see that having to filter on matching uri providers in a single
> property can be complicated, but would that be more complicated than having
> to consider all possible schema/context providers through distinct
> properties?
>
In SPARQL the latter is very easy. Just make a VALUES list of all the
properties you are interested in,
VALUES ?prop_wdt {wdt:P1111, wdt:P2222, wdt:P3333, wdt:P6666}
then look for
?item ?prop_wdt ?ext_id
Alternatively, if there is something characteristic about a whole set of
properties that you want to use, then add that information to the
wikidata item for the property. You will then be easily able to select
all the with that characteristic, eg:
?prop wdt:1234 wd:Q5678901
?prop wikibase:directClaim ?prop_wdt
This gives you the fine control to retrieve just the URIs of the
services you want, rather than only being able to retrieve everything
all lumped together.
Using distinct external-ID properties also makes it much easier to see
what properties are currently in play, for project tracking pages like
this one:
https://www.wikidata.org/wiki/Wikidata:WikiProject_BHL/Statistics:Titles#Titles_--_IDs
-- James.
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