HHH-18649 more work on TypedQueryReference in static metamodel

Author: gavinking

tooling/metamodel-generator/src/main/java/org/hibernate/processor/annotation/AnnotationMeta.java

@@ -13,7 +13,11 @@
 import org.hibernate.processor.util.Constants;
 import org.hibernate.processor.validation.ProcessorSessionFactory;
 import org.hibernate.processor.validation.Validation;
+import org.hibernate.query.criteria.JpaEntityJoin;
+import org.hibernate.query.criteria.JpaRoot;
+import org.hibernate.query.criteria.JpaSelection;
 import org.hibernate.query.sqm.tree.SqmStatement;
+import org.hibernate.query.sqm.tree.select.SqmSelectClause;
 import org.hibernate.query.sqm.tree.select.SqmSelectStatement;
 
 import javax.lang.model.element.AnnotationMirror;
@@ -103,25 +107,56 @@ private void handleNamedQuery(AnnotationMirror mirror, boolean checkHql) {
 									ProcessorSessionFactory.create( context.getProcessingEnvironment(),
 											context.getEntityNameMappings(), context.getEnumTypesByValue() )
 							);
-					if ( statement instanceof SqmSelectStatement
-							&& isQueryMethodName( name ) ) {
-						putMember( name,
-								new NamedQueryMethod(
-										this,
-										(SqmSelectStatement<?>) statement,
-										name.substring(1),
-										isRepository(),
-										getSessionType(),
-										getSessionVariableName(),
-										context.addNonnullAnnotation()
-								)
-						);
+					if ( statement instanceof SqmSelectStatement<?> selectStatement ) {
+						if ( isQueryMethodName( name ) ) {
+							putMember( name,
+									new NamedQueryMethod(
+											this,
+											selectStatement,
+											name.substring(1),
+											isRepository(),
+											getSessionType(),
+											getSessionVariableName(),
+											context.addNonnullAnnotation()
+									)
+							);
+						}
+						if ( !isJakartaDataStyle()
+								&& getAnnotationValue( mirror, "resultClass" ) == null ) {
+							final String resultType = resultType( selectStatement );
+							if ( resultType != null ) {
+								putMember( "QUERY_" + name,
+										new TypedMetaAttribute( this, name, "QUERY_", resultType,
+												"jakarta.persistence.TypedQueryReference" ) );
+							}
+						}
 					}
 				}
 			}
 		}
 	}
 
+	private static @Nullable String resultType(SqmSelectStatement<?> selectStatement) {
+		final JpaSelection<?> selection = selectStatement.getSelection();
+		if (selection == null) {
+			return null;
+		}
+		else if (selection instanceof SqmSelectClause from) {
+			return from.getSelectionItems().size() > 1
+					? "Object[]"
+					: from.getSelectionItems().get(0).getJavaTypeName();
+		}
+		else if (selection instanceof JpaRoot<?> root) {
+			return root.getModel().getTypeName();
+		}
+		else if (selection instanceof JpaEntityJoin<?, ?> join) {
+			return join.getModel().getTypeName();
+		}
+		else {
+			return selection.getJavaTypeName();
+		}
+	}
+
 	private static boolean isQueryMethodName(String name) {
 		return name.length() >= 2
 			&& name.charAt(0) == '#'
@@ -165,8 +200,9 @@ private void addAuxiliaryMembersForMirror(AnnotationMirror mirror, String prefix
 	private NameMetaAttribute auxiliaryMember(AnnotationMirror mirror, String prefix, String name) {
 		if ( !isJakartaDataStyle() && "QUERY_".equals(prefix) ) {
 			final AnnotationValue resultClass = getAnnotationValue( mirror, "resultClass" );
-			//TODO: if there is no explicit result class, obtain the result class by
-			//      type-checking the query (this is allowed but not required by JPA)
+			// if there is no explicit result class, we will infer it later by
+			// type checking the query (this is allowed but not required by JPA)
+			// and then we will replace this TypedMetaAttribute
 			return new TypedMetaAttribute( this, name, prefix,
 					resultClass == null ? JAVA_OBJECT : resultClass.getValue().toString(),
 					"jakarta.persistence.TypedQueryReference" );

tooling/metamodel-generator/src/main/java/org/hibernate/processor/annotation/NameMetaAttribute.java

@@ -54,7 +54,7 @@ public String getAttributeNameDeclarationString() {
 				.toString();
 	}
 
-	private String fieldName() {
+	String fieldName() {
 		return nameToFieldName(name.charAt(0) == '#' ? name.substring(1) : name);
 	}
 

tooling/metamodel-generator/src/main/java/org/hibernate/processor/annotation/TypedMetaAttribute.java

@@ -12,6 +12,7 @@
  * @author Gavin King
  */
 class TypedMetaAttribute extends NameMetaAttribute {
+	private final String prefix;
 	private final String resultType;
 	private final String referenceType;
 
@@ -22,6 +23,7 @@ public TypedMetaAttribute(
 			String resultType,
 			String referenceType) {
 		super( annotationMetaEntity, name, prefix );
+		this.prefix = prefix;
 		this.resultType = resultType;
 		this.referenceType = referenceType;
 	}
@@ -34,8 +36,13 @@ public boolean hasTypedAttribute() {
 	@Override
 	public String getAttributeDeclarationString() {
 		final Metamodel entity = getHostingEntity();
-		return new StringBuilder()
-				.append("\n/**\n * @see ")
+		final StringBuilder declaration = new StringBuilder();
+		declaration
+				.append("\n/**")
+				.append("\n * The query named {@value ")
+				.append(prefix)
+				.append(fieldName())
+				.append("}\n *\n * @see ")
 				.append(entity.getQualifiedName())
 				.append("\n **/\n")
 				.append("public static volatile ")
@@ -45,8 +52,11 @@ public String getAttributeDeclarationString() {
 				.append('>')
 				.append(' ')
 				.append('_')
-				.append(nameToMethodName(getPropertyName()))
-				.append(';')
-				.toString();
+				.append(nameToMethodName(getPropertyName()));
+		if ( "QUERY_".equals(prefix) ) { //UGLY!
+			declaration.append('_');
+		}
+		declaration.append(';');
+		return declaration.toString();
 	}
 }

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/namedquery/Book.java

@@ -11,6 +11,12 @@
 
 @Entity
 @NamedEntityGraph(name = "entityGraph")
+@NamedQuery(name="booksByTitle",
+		query = "from Book where title = ?1")
+@NamedQuery(name="booksByTitleVerbose",
+		query = "select book from Book book where book.title = ?1")
+@NamedQuery(name = "titlesWithIsbns",
+		query = "select title, isbn from Book")
 @NamedQuery(name = "#findByTitle",
 		query = "from Book where title like :titlePattern")
 @NamedQuery(name = "#findByTitleAndType",