Avoid unnecessary joins.

Original pull request #980

Author: schauder

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/query/JdbcQueryCreator.java

@@ -241,19 +241,19 @@ private SelectBuilder.SelectJoin selectBuilder(Table table) {
 
 			PersistentPropertyPathExtension extPath = new PersistentPropertyPathExtension(context, path);
 
-			// add a join if necessary
-			Join join = getJoin(sqlContext, extPath);
-			if (join != null) {
-				joinTables.add(join);
-			}
-
 			if (returnedType.needsCustomConstruction()) {
 				if (!returnedType.getInputProperties()
 						.contains(extPath.getRequiredPersistentPropertyPath().getBaseProperty().getName())) {
 					continue;
 				}
 			}
 
+			// add a join if necessary
+			Join join = getJoin(sqlContext, extPath);
+			if (join != null) {
+				joinTables.add(join);
+			}
+
 			Column column = getColumn(sqlContext, extPath);
 			if (column != null) {
 				columnExpressions.add(column);

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/repository/query/PartTreeJdbcQueryUnitTests.java

@@ -126,7 +126,7 @@ public void createsQueryToFindAllEntitiesByProjectionAttribute() throws Exceptio
 		PartTreeJdbcQuery jdbcQuery = createQuery(queryMethod);
 		ParametrizedQuery query = jdbcQuery.createQuery(getAccessor(queryMethod, new Object[] { "John" }), returnedType);
 
-		assertThat(query.getQuery()).isEqualTo("SELECT " + TABLE + ".\"FIRST_NAME\" AS \"FIRST_NAME\" " + JOIN_CLAUSE
+		assertThat(query.getQuery()).isEqualTo("SELECT " + TABLE + ".\"FIRST_NAME\" AS \"FIRST_NAME\" FROM \"users\""
 				+ " WHERE " + TABLE + ".\"FIRST_NAME\" = :first_name");
 	}
 
@@ -601,6 +601,8 @@ interface UserRepository extends Repository<User, Long> {
 
 		List<User> findAllByHated(Hobby hobby);
 
+		List<User> findAllByHatedName(String name);
+
 		List<User> findAllByHobbies(Object hobbies);
 
 		List<User> findAllByHobbyReference(Hobby hobby);