Unexpected error : "Use of ungrouped variable in projection of operation" ?

[tfrancart]

Unexpected error : "Use of ungrouped variable in projection of operation" ?

[tfrancart]

Updating to latest version 3.7.1 gives the same error

[tfrancart]

Could be related to the fact that ?count is the result of an aggregation, but also used in the expression (CONCAT(STR(?theLabel), ' (', STR(?count), ')') AS ?label)

[RubenVerborgh]

That must be it, yes. Can't tell top of my head whether or not it is correct (would need to spend some spec time), but I am leaning towards no (don't think you can use a destination variable in the SELECT clause).

To speed this up, can you gather spec evidence as to whether this should be allowed? https://www.w3.org/TR/sparql11-query/

[tfrancart]

I think the interesting paragraph is https://www.w3.org/TR/sparql11-query/#aggregateRestrictions, but not sure how to interpret that. I think it reads "what you do aggregates, you cannot use functions on other selected variables".

Which makes me think that using a CONCAT + a COUNT in the SELECT clause (whether or not the CONCAT uses the counted variable), is not legal.

[rubensworks]

Some SPARQL engines are a bit more liberal on this, but strictly this is not allowed by the SPARQL spec indeed.
But you can disable this check like this: https://github.com/RubenVerborgh/SPARQL.js?tab=readme-ov-file#validation

[RubenVerborgh]

So that brings the question down to whether ?x or ?count is the selected variable. Might be a good discussion for https://lists.w3.org/Archives/Public/public-sparql-dev/; okay to close here until more evidence comes along?

[tfrancart]

Some SPARQL engines are a bit more liberal on this

I would even say, all of those I have been using so far :-)

okay to close here until more evidence comes along?

OK to close, I need to rewrite the query as the following:

PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> 
PREFIX skos: <http://www.w3.org/2004/02/skos/core#> 
PREFIX rico: <https://www.ica.org/standards/RiC/ontology#> 
SELECT ?uri (CONCAT(STR(?theLabel), ' (', STR(?count), ')') AS ?label) ?hasChildren ?count
WHERE {
  {
  SELECT ?uri ?theLabel ?hasChildren (COUNT(?x) AS ?count)
  WHERE {
    {
      SELECT DISTINCT ?uri ?theLabel ?hasChildren
      WHERE { <http://data.archives-nationales.culture.gouv.fr/documentaryFormTypes> skos:hasTopConcept|^skos:topConceptOf ?uri .
        ?uri skos:prefLabel ?theLabel .
        FILTER(isIRI(?uri))
        FILTER(lang(?theLabel) = '' || lang(?theLabel) = 'en' || lang(?theLabel) = 'fr')
        OPTIONAL {
          ?uri skos:narrower|^skos:broader ?children .
        }
        BIND(IF(bound(?children),true,false) AS ?hasChildren)
      }
    }

    OPTIONAL {
      ?x a <https://sparna-git.github.io/sparnatural-demonstrateur-an/ontology#Archives> .
      ?x <https://sparna-git.github.io/sparnatural-demonstrateur-an/ontology#aPourTypeDeDocument> ?uri .
      # no range criteria
      # ?uri a <https://sparna-git.github.io/sparnatural-demonstrateur-an/ontology#TypeDeDocument> .
    }
  }
  GROUP BY ?uri ?theLabel ?hasChildren
  }
} ORDER BY UCASE(?label)