HHH-15733 Change convert logic to default to value for Map collections of basic types

hibernate-core/src/main/java/org/hibernate/boot/model/internal/CollectionBinder.java

@@ -2131,15 +2131,17 @@ private void handleElementCollection(XClass elementType, String hqlOrderBy) {
 				propertyHolder,
 				buildingContext
 		);
-		holder.prepare( property );
 
 		final Class<? extends CompositeUserType<?>> compositeUserType =
 				resolveCompositeUserType( property, elementClass, buildingContext );
-		if ( classType == EMBEDDABLE || compositeUserType != null ) {
+		boolean isComposite = classType == EMBEDDABLE || compositeUserType != null;
+		holder.prepare( property, isComposite );
+
+		if ( isComposite ) {
 			handleCompositeCollectionElement( hqlOrderBy, elementClass, holder, compositeUserType );
 		}
 		else {
-			handleCollectionElement(  elementType, hqlOrderBy, elementClass, holder );
+			handleCollectionElement( elementType, hqlOrderBy, elementClass, holder );
 		}
 	}
 

hibernate-core/src/main/java/org/hibernate/boot/model/internal/CollectionPropertyHolder.java

@@ -78,6 +78,7 @@ public Collection getCollectionBinding() {
 
 	private void buildAttributeConversionInfoMaps(
 			XProperty collectionProperty,
+			boolean isComposite,
 			Map<String,AttributeConversionInfo> elementAttributeConversionInfoMap,
 			Map<String,AttributeConversionInfo> keyAttributeConversionInfoMap) {
 		if ( collectionProperty == null ) {
@@ -88,7 +89,13 @@ private void buildAttributeConversionInfoMaps(
 		{
 			final Convert convertAnnotation = collectionProperty.getAnnotation( Convert.class );
 			if ( convertAnnotation != null ) {
-				applyLocalConvert( convertAnnotation, collectionProperty, elementAttributeConversionInfoMap, keyAttributeConversionInfoMap );
+				applyLocalConvert(
+						convertAnnotation,
+						collectionProperty,
+						isComposite,
+						elementAttributeConversionInfoMap,
+						keyAttributeConversionInfoMap
+				);
 			}
 		}
 
@@ -99,6 +106,7 @@ private void buildAttributeConversionInfoMaps(
 					applyLocalConvert(
 							convertAnnotation,
 							collectionProperty,
+							isComposite,
 							elementAttributeConversionInfoMap,
 							keyAttributeConversionInfoMap
 					);
@@ -110,14 +118,15 @@ private void buildAttributeConversionInfoMaps(
 	private void applyLocalConvert(
 			Convert convertAnnotation,
 			XProperty collectionProperty,
+			boolean isComposite,
 			Map<String,AttributeConversionInfo> elementAttributeConversionInfoMap,
 			Map<String,AttributeConversionInfo> keyAttributeConversionInfoMap) {
 
-		// IMPL NOTE : the rules here are quite more lenient than what JPA says.  For example, JPA says
+		// IMPL NOTE : the rules here are quite more lenient than what JPA says.  For example, JPA says that @Convert
-		// that @Convert on a Map always needs to specify attributeName of key/value (or prefixed with
+		// on a Map of basic types should default to "value" but it should explicitly specify attributeName of "key"
-		// key./value. for embedded paths).  However, we try to see if conversion of either is disabled
+		// (or prefixed with "key." for embedded paths) to be applied on the key.  However, we try to see if conversion
-		// for whatever reason.  For example, if the Map is annotated with @Enumerated the elements cannot
+		// of either is disabled for whatever reason.  For example, if the Map is annotated with @Enumerated the
-		// be converted so any @Convert likely meant the key, so we apply it to the key
+		// elements cannot be converted so any @Convert likely meant the key, so we apply it to the key
 
 		final AttributeConversionInfo info = new AttributeConversionInfo( convertAnnotation, collectionProperty );
 		if ( collection.isMap() ) {
@@ -132,10 +141,15 @@ private void applyLocalConvert(
 		if ( isEmpty( info.getAttributeName() ) ) {
 			// the @Convert did not name an attribute...
 			if ( canElementBeConverted && canKeyBeConverted ) {
-				throw new IllegalStateException(
+				if ( !isComposite ) {
-						"@Convert placed on Map attribute [" + collection.getRole()
+					// if element is of basic type default to "value"
-								+ "] must define attributeName of 'key' or 'value'"
+					elementAttributeConversionInfoMap.put( "", info );
-				);
+				}
+				else {
+					throw new IllegalStateException(
+							"@Convert placed on Map attribute [" + collection.getRole()
+									+ "] of non-basic types must define attributeName of 'key' or 'value'" );
+				}
 			}
 			else if ( canKeyBeConverted ) {
 				keyAttributeConversionInfoMap.put( "", info );
@@ -325,7 +339,7 @@ public String toString() {
 
 	boolean prepared;
 
-	public void prepare(XProperty collectionProperty) {
+	public void prepare(XProperty collectionProperty, boolean isComposite) {
 		// fugly
 		if ( prepared ) {
 			return;
@@ -377,7 +391,12 @@ else if ( collectionProperty.isAnnotationPresent( CollectionType.class ) ) {
 		// Is it valid to reference a collection attribute in a @Convert attached to the owner (entity) by path?
 		// if so we should pass in 'clazzToProcess' also
 		if ( canKeyBeConverted || canElementBeConverted ) {
-			buildAttributeConversionInfoMaps( collectionProperty, elementAttributeConversionInfoMap, keyAttributeConversionInfoMap );
+			buildAttributeConversionInfoMaps(
+					collectionProperty,
+					isComposite,
+					elementAttributeConversionInfoMap,
+					keyAttributeConversionInfoMap
+			);
 		}
 	}
 

hibernate-core/src/main/java/org/hibernate/boot/model/internal/MapBinder.java

@@ -37,6 +37,7 @@
 import org.hibernate.mapping.Table;
 import org.hibernate.mapping.Value;
 import org.hibernate.resource.beans.spi.ManagedBean;
+import org.hibernate.type.BasicType;
 import org.hibernate.usertype.CompositeUserType;
 import org.hibernate.usertype.UserCollectionType;
 
@@ -278,7 +279,7 @@ private CollectionPropertyHolder buildCollectionPropertyHolder(
 		// 'holder' is the CollectionPropertyHolder.
 		// 'property' is the collection XProperty
 		propertyHolder.startingProperty( property );
-		holder.prepare(property);
+		holder.prepare( property, !( collection.getKey().getType() instanceof BasicType ) );
 		return holder;
 	}
 

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/converted/converter/map/MapElementBaseTypeConversionTest.java

@@ -67,16 +67,9 @@ public static class Customer {
 		private Integer id;
 
 		@ElementCollection(fetch = FetchType.EAGER)
-		@Convert(converter = MyStringConverter.class)
+		@Convert(converter = MyStringConverter.class) // note omitted attributeName
 		private final Map<String, String> colors = new HashMap<>();
 
-		public Customer() {
-		}
-
-		public Customer(Integer id) {
-			this.id = id;
-		}
-
 		public Map<String, String> getColors() {
 			return colors;
 		}