Imported_from seems to break ask-queries with SPARQL-backend

[simontaurus]

Setup

• SMW version: 4.1.1 (also tested: 3.2.3)
• MW version: 1.39.3 (also tested: 1.35.7)
• PHP version: 7.4.33 (also tested: 8.1)
• DB system (MySQL, Blazegraph, etc.) and version: MySQL 8.0.17, Blazegraph 2.1.5

Issue

[[Imported from::...]] statements seem to break ask-queries when a SPARQL-backend is used.
I asume this is due to the change from the local IRI (/id/<title>) to the imported one (e. g. foaf:Person) as primary identifier.

Steps to reproduce the observation:

1. Create a page with an [[Imported from::foaf:Person]] statement, e. g. ImportedFromTestPage
2. Query for that page with [[Imported_from::foaf:Person]], e. g. https://demo.open-semantic-lab.org/w/api.php?action=ask&query=[[Imported_from::foaf:Person]]
3. Result is empty while in the sandbox instance it works as expected

[simontaurus]

Update:

The test query above works after purging the page and the iri replacement within the SPARQL query seems fine, so category:ImportedFromTestPage gets replaced with foaf:Person

But when I set the displaytitle to ImportedFromTestPageDisplayTitle with {{DISPLAYTITLE: ImportedFromTestPageDisplayTitle}}, the query https://demo.open-semantic-lab.org/w/api.php?action=ask&query=[[:Category:ImportedFromTestPage]]|?Imported_from returns

        "results": {
            "Category:ImportedFromTestPageDisplayTitle": {
                "printouts": {
                    "Imported from": []
                },
                "fulltext": "Category:ImportedFromTestPageDisplayTitle",
                "fullurl": "https://demo.open-semantic-lab.org/wiki/Category:ImportedFromTestPageDisplayTitle",
                "namespace": 14,
                "exists": "",
                "displaytitle": ""
            }
        },

so the actual title gets replaced with the display title and fulltext points to a non-existing page which leads to errors in any consumer.

Sandbox works fine:
https://sandbox.semantic-mediawiki.net/w/api.php?action=ask&query=[[Imported_from::foaf:Person]]|?Imported_from

Looking at the logs it looks like the actual title gets replaced in the SQL queries by the display title after the SPARQL query was executet:

SMW\SQLStore\EntityStore\EntityIdFinder::fetchFromTableByTitle [0.001s] db: SELECT ... WHERE smw_title = 'ImportedFromTestPage' ...
SMW\SPARQLStore\QueryEngine\ConditionBuilder ...
SMW\SQLStore\EntityStore\EntityIdFinder::fetchFromTableByTitle [0.001s] db: SELECT ... WHERE smw_title = 'ImportedFromTestPageDisplayTitle' ...

[simontaurus]

Update:

The actual errors occurs here for self-queries (e. g. [[{{FULLPAGENAME}}]] ):

rdfs:label, which holds the display title, is used as DB_KEY, resulting in an invalid dataItem. Instead swivt:page (after removing / spliting at $wgArticlePath + namespace, e. g. Category-3A) or rdfs:isDefinedBy (after removing / spliting at Special:ExportRDF/ + namespace, e. g. Category-3A) should be used.

SemanticMediaWiki/src/Exporter/DataItemMatchFinder.php

Lines 136 to 163 in 13c7bbe

	$respositoryResult = $this->store->getConnection( 'sparql' )->select(
	'?v1 ?v2',
	"<$uri> rdfs:label ?v1 . <$uri> swivt:wikiNamespace ?v2",
	[ 'LIMIT' => 1 ]
	);
	$expElements = $respositoryResult->current();
	if ( $expElements !== false ) {
	// ?v1
	if ( isset( $expElements[0] ) ) {
	$dbKey = $expElements[0]->getLexicalForm();
	} else {
	$dbKey = 'UNKNOWN';
	}
	// ?v2
	if ( isset( $expElements[1] ) ) {
	$namespace = strval( $expElements[1]->getLexicalForm() );
	} else {
	$namespace = NS_MAIN;
	}
	$dataItem = new DIWikiPage(
	$this->getFittingDBKey( $dbKey, $namespace ),
	$namespace
	);

But since the ExpElement passed to matchExpElement() e. g.

{"options":null,"value":"ImportedFromTestPage#14##","_type_":"SMW\\DIWikiPage","sortkey":null,"contextReference":null,"pageLanguage":null,"id":0}

already contains correct DB_KEY and namespace, a lookup in the triplestore is maybe not needed at all.

SemanticMediaWiki/src/Exporter/DataItemMatchFinder.php

Lines 52 to 70 in 13c7bbe

	public function matchExpElement( ExpElement $expElement ) {
	$dataItem = null;
	if ( !$expElement instanceof ExpResource ) {
	return $dataItem;
	}
	$uri = $expElement->getUri();
	if ( strpos( $uri, $this->wikiNamespace ) !== false ) {
	$dataItem = $this->matchToWikiNamespaceUri( $uri );
	} else {
	// Not in wikiNamespace therefore most likely an imported URI
	$dataItem = $this->matchToUnknownWikiNamespaceUri( $uri );
	}
	return $dataItem;
	}