SPARQL filter

[sinanatra]

Which SPARQL filter are supported now?

FILTER(contains(?var, "value to match)) does not filter anything.

[TallTed]

Well... You're missing a closing quotation mark. But maybe this isn't the FILTER clause you're actually using. So maybe show us the clause you're actually using, and the value you're expecting it to match?

[sinanatra]

ops, yes it should have been FILTER(contains(?var, "value to match")). Anyway, i want to filter all the E12_Production which contains a specific string in the P3_has_note, e.g. Datierung Kleidung. This is the property in my turtle

@prefix crm: <http://erlangen-crm.org/200717/>.

<_:b2>
    a crm:E12_Production;
    crm:P3_has_note
    "Datierung Kleidung (Modewissenschaftliche Einsch\\u00e4tzung)";
    crm:P4_has_time-span <_:b3>;
    crm:P70i_is_documented_in items:6076.
<_:b3> a crm:E52_Time-Span; crm:P82_at_some_time_within "01.01.1550 - 31.12.1599".

Launching this query i don't get any filtering:

PREFIX crm: <http://erlangen-crm.org/200717/>.
SELECT *
WHERE {
   ?productionEvent a crm:E12_Production ;
    crm:P4_has_time-span  ?timeSpan .

    ?productionEvent a crm:E12_Production ;
    crm:P3_has_note ?note 
    FILTER(contains(?note, "Datierung Kleidung")) .

    ?timeSpan  crm:P82_at_some_time_within ?time . 
}

[TallTed]

OK, that looks more like what I was expecting to see, and it does look like you should get the desired result. What is the target SPARQL engine (name, version, and platform; all may matter)? Is it a publicly accessible endpoint (such that we can experiment)?

[sinanatra]

So far it's not public. I am fetching data from the API (structured in json-ld) of our Omeka S server, which i then parse with $rdf.parse and i am now trying to query with $rdf.SPARQLToQuery.

[TallTed]

My best guess from the limited information at hand is a bug in the SPARQL processor. A log from it, and possibly logs from any other components involved that can produce them, may help confirm that and/or pinpoint what the issue is.

[jeff-zucker]

The SPARQL engine in rdflib is not fully SPARQL 1.1 compliant and is also, unfortunately, not very well documented. It does NOT support Filter.

[sinanatra]

is the support planned for the future?

[jeff-zucker]

We are considering options on SPARQL, possibly piggy-backing on another engine such as @RubenVerborgh's SPARQL.js . Rdflib's parsing may be weak but excels in loading (handles CORS, alternate formats) and following (loading all documents in a query, not assuming a single triplestore). It's possible to use comunica or sparql.js in conjunction with rdlib though it requires some dumping of quads from one format to the other. But no, sorry, no specific plans on FILTER.

[RubenVerborgh]

@jeff-zucker That's great. Note that both the loading and the link following are part of Comunica as well. Comunica has extended format support (also parsing JSON-LD inside of HTML, for instance) and extensive configurations for different kinds of traversal. So I can recommend it for more advanced SPARQL queries.