Optimize SPARQL query for single entity metadata using wikibase:label service

- Use SERVICE wikibase:label for efficient retrieval of labels and descriptions in preferred language
- Remove redundant label/description fetching logic
- Prevent Cartesian product and improve query performance for

app/src/main/java/fr/free/nrw/commons/nearby/model/NearbyResultItem.kt

@@ -7,6 +7,7 @@ class NearbyResultItem(
     private val wikipediaArticle: ResultTuple?,
     private val commonsArticle: ResultTuple?,
     private val location: ResultTuple?,
+    @field:SerializedName("itemLabel")
     private val label: ResultTuple?,
     @field:SerializedName("streetAddress") private val address: ResultTuple?,
     private val icon: ResultTuple?,
@@ -15,7 +16,7 @@ class NearbyResultItem(
     @field:SerializedName("commonsCategory") private val commonsCategory: ResultTuple?,
     @field:SerializedName("pic") private val pic: ResultTuple?,
     @field:SerializedName("destroyed") private val destroyed: ResultTuple?,
-    @field:SerializedName("description") private val description: ResultTuple?,
+    @field:SerializedName("itemDescription") private val description: ResultTuple?,
     @field:SerializedName("endTime") private val endTime: ResultTuple?,
     @field:SerializedName("monument") private val monument: ResultTuple?,
     @field:SerializedName("dateOfOfficialClosure") private val dateOfOfficialClosure: ResultTuple?,

app/src/main/resources/queries/query_for_item.rq

@@ -1,45 +1,26 @@
 SELECT
   ?item
-  (SAMPLE(?label) AS ?label)
+  ?itemLabel
-  (SAMPLE(?class) AS ?class)
+  ?itemDescription
-  (SAMPLE(?description) AS ?description)
+  ?class
-  (SAMPLE(?classLabel) AS ?classLabel)
+  ?classLabel
-  (SAMPLE(?pic) AS ?pic)
+  ?pic
-  (SAMPLE(?destroyed) AS ?destroyed)
+  ?destroyed
-  (SAMPLE(?endTime) AS ?endTime)
+  ?endTime
-  (SAMPLE(?wikipediaArticle) AS ?wikipediaArticle)
+  ?wikipediaArticle
-  (SAMPLE(?commonsArticle) AS ?commonsArticle)
+  ?commonsArticle
-  (SAMPLE(?commonsCategory) AS ?commonsCategory)
+  ?commonsCategory
-  (SAMPLE(?dateOfOfficialClosure) AS ?dateOfOfficialClosure)
+  ?dateOfOfficialClosure
-  (SAMPLE(?pointInTime) AS ?pointInTime)
+  ?pointInTime
 WHERE {
   SERVICE <https://query.wikidata.org/sparql> {
-    values ?item {
+    VALUES ?item { ${ENTITY} }
-      ${ENTITY}
-    }
   }
 
-  # Get the label in the preferred language of the user, or any other language if no label is available in that language.
+  # Get item label/class label/description in the preferred language of the user
-  OPTIONAL {?item rdfs:label ?itemLabelPreferredLanguage. FILTER (lang(?itemLabelPreferredLanguage) = "${LANG}")}
+   SERVICE wikibase:label { bd:serviceParam wikibase:language "${LANG},en". }
-  OPTIONAL {?item rdfs:label ?itemLabelAnyLanguage}
-  BIND(COALESCE(?itemLabelPreferredLanguage, ?itemLabelAnyLanguage, "?") as ?label)
 
-  # Get the description in the preferred language of the user, or any other language if no description is available in that language.
+  OPTIONAL { ?item p:P31/ps:P31 ?class. }
-  OPTIONAL {?item schema:description ?itemDescriptionPreferredLanguage. FILTER (lang(?itemDescriptionPreferredLanguage) = "${LANG}")}
-  OPTIONAL {?item schema:description ?itemDescriptionAnyLanguage}
-  BIND(COALESCE(?itemDescriptionPreferredLanguage, ?itemDescriptionAnyLanguage, "?") as ?description)
-
-  # Get the class label in the preferred language of the user, or any other language if no label is available in that language.
-  OPTIONAL {
-  ?item p:P31/ps:P31 ?class.
-    OPTIONAL {?class rdfs:label ?classLabelPreferredLanguage. FILTER (lang(?classLabelPreferredLanguage) = "${LANG}")}
-    OPTIONAL {?class rdfs:label ?classLabelAnyLanguage}
-    BIND(COALESCE(?classLabelPreferredLanguage, ?classLabelAnyLanguage, "?") as ?classLabel)
-  }
-
-  OPTIONAL {
-  ?item p:P31/ps:P31 ?class.
-  }
 
   # Get picture
   OPTIONAL {?item wdt:P18 ?pic}
@@ -54,15 +35,9 @@ WHERE {
   OPTIONAL {?item wdt:P373 ?commonsCategory}
 
   # Get Wikipedia article
-  OPTIONAL {
+  OPTIONAL { ?wikipediaArticle schema:about ?item;schema:isPartOf <https://en.wikipedia.org/>. }
-    ?wikipediaArticle schema:about ?item.
-    ?wikipediaArticle schema:isPartOf <https://en.wikipedia.org/>. # TODO internationalization
-  }
 
   # Get Commons article
-  OPTIONAL {
+  OPTIONAL { ?commonsArticle schema:about ?item; schema:isPartOf <https://commons.wikimedia.org/>. }
-    ?commonsArticle schema:about ?item.
+
-    ?commonsArticle schema:isPartOf <https://commons.wikimedia.org/>.
-  }
 }
-GROUP BY ?item