HSEARCH-3905 Add parent object field path to the "field_names" field when a value is added to a dynamic child field

This will allow detection of these dynamic children fields when
executing an "exists" predicate on the object field.

Signed-off-by: Yoann Rodière <yoann@hibernate.org>

Author: yrodiere

backend/lucene/src/main/java/org/hibernate/search/backend/lucene/document/impl/AbstractLuceneDocumentElementBuilder.java

@@ -158,6 +158,16 @@ void contribute(MultiTenancyStrategy multiTenancyStrategy, String tenantId, Stri
 		}
 	}
 
+	/**
+	 * When executing an exists() predicate on an object field that contains dynamic value field,
+	 * we don't necessarily know all the possible child value fields,
+	 * so we cannot just execute {@code exists(childField1) OR exists(childField2) OR ... OR exists(childFieldN)}.
+	 * That's why we keep track of the fact that
+	 * "for this document, this object field exists because it contains at least one dynamic value".
+	 * This is done by adding the path of the object field to the "fieldNames" field.
+	 */
+	abstract void ensureDynamicValueDetectedByExistsPredicateOnObjectField();
+
 	private <F> void addValue(LuceneIndexSchemaValueFieldNode<F> node, F value) {
 		LuceneIndexSchemaObjectNode expectedParentNode = node.parent();
 		checkTreeConsistency( expectedParentNode );
@@ -170,6 +180,9 @@ private <F> void addValue(LuceneIndexSchemaValueFieldNode<F> node, F value) {
 		}
 
 		type.codec().addToDocument( documentContent, absolutePath, value );
+		if ( value != null && node.dynamic() ) {
+			ensureDynamicValueDetectedByExistsPredicateOnObjectField();
+		}
 	}
 
 	private DocumentElement addObject(LuceneIndexSchemaObjectFieldNode node, boolean nullObject) {
@@ -189,12 +202,12 @@ private DocumentElement addObject(LuceneIndexSchemaObjectFieldNode node, boolean
 		switch ( node.structure() ) {
 			case NESTED:
 				LuceneNestedObjectFieldBuilder nestedDocumentBuilder =
-						new LuceneNestedObjectFieldBuilder( model, node );
+						new LuceneNestedObjectFieldBuilder( model, node, this );
 				addNestedObjectDocumentBuilder( nestedDocumentBuilder );
 				return nestedDocumentBuilder;
 			default:
 				LuceneFlattenedObjectFieldBuilder flattenedDocumentBuilder =
-						new LuceneFlattenedObjectFieldBuilder( model, node, documentContent );
+						new LuceneFlattenedObjectFieldBuilder( model, node, this, documentContent );
 				addFlattenedObjectDocumentBuilder( flattenedDocumentBuilder );
 				return flattenedDocumentBuilder;
 		}

backend/lucene/src/main/java/org/hibernate/search/backend/lucene/document/impl/AbstractLuceneObjectFieldBuilder.java

@@ -0,0 +1,31 @@
+/*
+ * Hibernate Search, full-text search for your domain model
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.search.backend.lucene.document.impl;
+
+import org.hibernate.search.backend.lucene.document.model.impl.LuceneIndexModel;
+import org.hibernate.search.backend.lucene.document.model.impl.LuceneIndexSchemaObjectFieldNode;
+
+class AbstractLuceneObjectFieldBuilder extends AbstractLuceneDocumentElementBuilder {
+
+	private final AbstractLuceneDocumentElementBuilder parent;
+
+	AbstractLuceneObjectFieldBuilder(LuceneIndexModel model, LuceneIndexSchemaObjectFieldNode schemaNode,
+			AbstractLuceneDocumentElementBuilder parent, LuceneDocumentContentImpl documentContent) {
+		super( model, schemaNode, documentContent );
+		this.parent = parent;
+	}
+
+	@Override
+	void ensureDynamicValueDetectedByExistsPredicateOnObjectField() {
+		documentContent.addFieldName( schemaNode.absolutePath() );
+		if ( schemaNode.dynamic() ) {
+			// If this object field is dynamic,
+			// the parent object's metadata will not include it, so we must propagate the information.
+			parent.ensureDynamicValueDetectedByExistsPredicateOnObjectField();
+		}
+	}
+}

backend/lucene/src/main/java/org/hibernate/search/backend/lucene/document/impl/LuceneFlattenedObjectFieldBuilder.java

@@ -15,16 +15,16 @@
 import org.hibernate.search.backend.lucene.logging.impl.Log;
 import org.hibernate.search.util.common.logging.impl.LoggerFactory;
 
-class LuceneFlattenedObjectFieldBuilder extends AbstractLuceneDocumentElementBuilder {
+class LuceneFlattenedObjectFieldBuilder extends AbstractLuceneObjectFieldBuilder {
 
 	private static final Log log = LoggerFactory.make( Log.class, MethodHandles.lookup() );
 
 	private final Set<String> encounteredFields = new HashSet<>();
 
 	LuceneFlattenedObjectFieldBuilder(LuceneIndexModel model, LuceneIndexSchemaObjectFieldNode schemaNode,
-			LuceneDocumentContentImpl documentContent) {
+			AbstractLuceneDocumentElementBuilder parent, LuceneDocumentContentImpl documentContent) {
 		// The document content is not ours: it's the parent's.
-		super( model, schemaNode, documentContent );
+		super( model, schemaNode, parent, documentContent );
 	}
 
 	@Override

backend/lucene/src/main/java/org/hibernate/search/backend/lucene/document/impl/LuceneNestedObjectFieldBuilder.java

@@ -16,10 +16,11 @@
 import org.apache.lucene.document.Document;
 
 
-class LuceneNestedObjectFieldBuilder extends AbstractLuceneDocumentElementBuilder {
+class LuceneNestedObjectFieldBuilder extends AbstractLuceneObjectFieldBuilder {
 
-	LuceneNestedObjectFieldBuilder(LuceneIndexModel model, LuceneIndexSchemaObjectFieldNode schemaNode) {
-		super( model, schemaNode, new LuceneDocumentContentImpl() );
+	LuceneNestedObjectFieldBuilder(LuceneIndexModel model, LuceneIndexSchemaObjectFieldNode schemaNode,
+			AbstractLuceneDocumentElementBuilder parent) {
+		super( model, schemaNode, parent, new LuceneDocumentContentImpl() );
 	}
 
 	@Override

backend/lucene/src/main/java/org/hibernate/search/backend/lucene/document/impl/LuceneRootDocumentBuilder.java

@@ -32,6 +32,11 @@ public LuceneIndexEntry build(String tenantId, String id, String routingKey) {
 		);
 	}
 
+	@Override
+	void ensureDynamicValueDetectedByExistsPredicateOnObjectField() {
+		// This is not an object field: nothing to do.
+	}
+
 	private List<Document> assembleDocuments(MultiTenancyStrategy multiTenancyStrategy,
 			String tenantId, String id, String routingKey) {
 		// We own the document content, so we finalize it ourselves.