extend the "pivot entity" selection with a free format sparql query

[marc-portier]

Currently, when configuring the mapping we are narrowing the items indexed simply by indicating their rdf:type

This is applied in a sparql query that actually finds the entities to index. We hereby suggest that we could further tweak the where clause of that sparql statement so it can be better tuned to specific needs:

Concrete use-case at hand:

• For the BODC skos terms, and the marineregions we would like to filter out the items that are deprecated
  FILTER NOT EXISTS {?entity owl:deprecated "true"^^xsd:bool .}

Open question:

• Unsure (open to implementation?) if these kind of extra filters should be applied during mapping-config as suggested here, or during search (widget-config)

UI suggestions:

• Considering the fact that free-format sparql can contain syntax issues, or result in undesired effects (i.e. too little selected entities) it would be nice if the UI can give some "dry-run-testing-feedback" --> e.g. returning the count(?entity) result
• Considering the fact that all ends up being one sparql statement, we could question if the current support of type-only where clause still needs to be presented in its current form - or as a sparql generating 'wizard' ?