GraphQL filters with RDF4J module

[hugovanversendaal]

Hi,

I'm trying to use GraphQL filters with the RDF4J backend module, but I'm not getting the expected result.

I'm using the following setup:

• data.trig file from the example folder: https://github.com/dotwebstack/dotwebstack-framework/blob/v0.4/example/example-rdf4j/src/main/resources/config/data/data.trig
• shapes.trig file from the example folder: https://github.com/dotwebstack/dotwebstack-framework/blob/v0.4/example/example-rdf4j/src/main/resources/config/shapes/shapes.trig
• dotwebstack.yaml containing the snippet from the documentation: https://dotwebstack.org/dotwebstack-framework/#/core/filtering?id=setup
• Query with equals-filter (https://dotwebstack.org/dotwebstack-framework/#/core/filtering?id=equals-filter):

query {
    beers(filter: { name: {eq: "Beer 1"} }) {
        identifier
        name
    }
}

The expected result is:

{
  "data": {
    "beers": [
      {
        "identifier": "b0e7cf18-e3ce-439b-a63e-034c8452f59c",
        "name": "Beer 1"
      }
    ]
  }
}

The actual result is:

{
  "data": {
    "beers": [
      {
        "identifier": "b0e7cf18-e3ce-439b-a63e-034c8452f59c",
        "name": "Beer 1"
      },
      {
        "identifier": "1295f4c1-846b-440c-b302-80bbc1f9f3a9",
        "name": "Beer 2"
      },
      {
        "identifier": "973832e7-1dd9-4683-a039-22390b1c1995",
        "name": "Beer 3"
      },
      {
        "identifier": "a5148422-be13-452a-b9fa-e72c155df3b2",
        "name": "Beer 4"
      },
      {
        "identifier": "766883b5-3482-41cf-a66d-a81e79a4f0ed",
        "name": "Beer 5"
      }
    ]
  }
}

Below is the SPARQL-query in the logging:

2023-08-22 09:43:12 2023-08-22T07:43:12.332Z DEBUG 1 --- [or-http-epoll-3] o.d.framework.backend.rdf4j.query.Query  : Executing query: SELECT * 
2023-08-22 09:43:12 WHERE { VALUES ?x2 {<https://github.com/dotwebstack/beer/def#Beverage> <https://github.com/dotwebstack/beer/def#Beer>}
2023-08-22 09:43:12 ?x1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>/<http://www.w3.org/2000/01/rdf-schema#subClassOf>* ?x2 .
2023-08-22 09:43:12 ?x1 <https://github.com/dotwebstack/beer/def#identifier> ?x3 .
2023-08-22 09:43:12 ?x1 <http://schema.org/name> ?x4 . }

[pmaria]

Hi @hugovanversendaal , I'm afraid that the RDF4J backend module is not yet feature complete and as such does not yet support filters amongst some other features. This is not made very clear at the moment.

I'm afraid there is currently no perspective on any development on the RDF4J backend in the near future from our side since our primary usage is of the Postgres backend.

Could you perhaps share a bit on how are you aiming to use the RDF4J backend? What kind of functionality would you need?

[hugovanversendaal]

Hi @pmaria,

Thanks for the explanation. My team uses RDF4J to distribute linked data via a SPARQL endpoint. However, some of our customers prefer a more user friendly interface to retrieve the data and require simple JSON results. That's why DotWebStack is very convenient for us.

Two features would be very useful:

• Filtering as described in de DWS documentation. For my team, being able to filter on date would be most useful.
• Interfaces. This is not described in the documentation, but it seems to be implemented to some extent.

[pmaria]

Hi @hugovanversendaal

Thanks for your response.

Would your team be open and able to contribute? If so, we could plan a meeting to discuss.

[hugovanversendaal]

Hi @pmaria,

I will forward the question to the rest of my team and will let you know what the outcome is. After today, I will be out of office for three weeks, so this may take while.