Use case-insensitive collation as default for Mongo pagination

Adds a default case-insensitive collation to DefaultMongoPaginationHelper
so callers get case-insensitive, numeric-aware sorting without
per-query workarounds. PaginatedStreamService drops its manual
$toLower field transformation in favor of the shared collation.

Author: dennisoelkers

graylog2-server/src/main/java/org/graylog2/database/pagination/DefaultMongoPaginationHelper.java

@@ -22,6 +22,7 @@
 import com.mongodb.client.MongoIterable;
 import com.mongodb.client.model.Aggregates;
 import com.mongodb.client.model.Collation;
+import com.mongodb.client.model.CollationStrength;
 import org.bson.conversions.Bson;
 import org.graylog2.database.MongoCollection;
 import org.graylog2.database.MongoEntity;
@@ -32,8 +33,10 @@
 import org.slf4j.LoggerFactory;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Predicate;
 
+import static com.google.common.base.MoreObjects.firstNonNull;
 import static com.google.common.base.Preconditions.checkArgument;
 import static org.graylog2.database.utils.MongoUtils.stream;
 
@@ -46,6 +49,11 @@
  */
 public class DefaultMongoPaginationHelper<T extends MongoEntity> implements MongoPaginationHelper<T> {
     private static final Logger LOG = LoggerFactory.getLogger(DefaultMongoPaginationHelper.class);
+    public static final Collation DEFAULT_COLLATION_WITH_CASE_INSENSITIVE_SORTING = Collation.builder()
+            .locale(Locale.ENGLISH.toLanguageTag())
+            .collationStrength(CollationStrength.SECONDARY)
+            .numericOrdering(true)
+            .build();
 
     private final MongoCollection<T> collection;
     private final Bson filter;
@@ -81,7 +89,7 @@ private DefaultMongoPaginationHelper(MongoCollection<T> collection,
         this.perPage = perPage;
         this.includeGrandTotal = includeGrandTotal;
         this.grandTotalFilter = grandTotalFilter;
-        this.collation = collation;
+        this.collation = firstNonNull(collation, DEFAULT_COLLATION_WITH_CASE_INSENSITIVE_SORTING);
         this.pipeline = pipeline;
         this.postSortPipeline = postSortPipeline;
         this.includeSourceMetadata = includeSourceMetadata;

graylog2-server/src/main/java/org/graylog2/streams/PaginatedStreamService.java

@@ -27,6 +27,7 @@
 import org.graylog2.database.MongoCollections;
 import org.graylog2.database.PaginatedList;
 import org.graylog2.database.entities.EntityScopeService;
+import org.graylog2.database.pagination.DefaultMongoPaginationHelper;
 import org.graylog2.database.utils.MongoUtils;
 import org.graylog2.indexer.indexset.MongoIndexSetService;
 import org.graylog2.rest.models.SortOrder;
@@ -35,9 +36,7 @@
 import java.util.function.Predicate;
 
 public class PaginatedStreamService {
-
     private static final String COLLECTION_NAME = "streams";
-    private static final List<String> STRING_FIELDS = List.of("title", "description", "index_set_title");
     private final MongoCollection<StreamDTO> collection;
     private final EntityScopeService scopeService;
 
@@ -73,20 +72,14 @@ public PaginatedList<StreamImpl> findPaginated(Bson dbQuery, //query executed on
                     .add(Aggregates.unset("index_set"));
         }
 
-        if (isStringField(sortField)) {
-            pipelineBuilder.add(Aggregates.set(new Field<>("lower" + sortField, doc("$toLower", "$" + sortField))))
-                    .add(Aggregates.sort(order.toBsonSort("lower" + sortField)))
-                    .add(Aggregates.unset("lower" + sortField));
-        } else {
-            pipelineBuilder.add(Aggregates.sort(order.toBsonSort(sortField)));
-        }
+        pipelineBuilder.add(Aggregates.sort(order.toBsonSort(sortField)));
 
         if (sortField.equals("index_set_title")) {
             pipelineBuilder.add(Aggregates.unset("index_set_title"));
         }
 
         final List<StreamImpl> streamsList;
-        try (final var results = MongoUtils.stream(collection.aggregate(pipelineBuilder.build()))) {
+        try (final var results = MongoUtils.stream(collection.aggregate(pipelineBuilder.build()).collation(DefaultMongoPaginationHelper.DEFAULT_COLLATION_WITH_CASE_INSENSITIVE_SORTING))) {
             streamsList = results
                     // Since we are bypassing the StreamService which properly sets the isEditable field when loading
                     // streams we need to set the field here.
@@ -111,10 +104,6 @@ public PaginatedList<StreamImpl> findPaginated(Bson dbQuery, //query executed on
         return new PaginatedList<>(paginatedStreams, streamsList.size(), page, perPage, grandTotal);
     }
 
-    private boolean isStringField(String sortField) {
-        return STRING_FIELDS.contains(sortField);
-    }
-
     private Document doc(String key, Object value) {
         return new Document(key, value);
     }