From 6e1b89c46c190dcccfdca7dd00f147c46d558fce Mon Sep 17 00:00:00 2001
From: Victor Uria Valle <victor.uria.valle@cern.ch>
Date: Tue, 21 Nov 2023 14:23:26 +0100
Subject: [PATCH] Add queryForOptional method in JdbcTemplate

---
 .../jdbc/core/JdbcTemplate.java               | 22 +++++++++++++
 .../jdbc/core/JdbcTemplateQueryTests.java     | 33 +++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java b/spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java
index 37bd61f2b3ac..6166342a2c5b 100644
--- a/spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java
+++ b/spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java
@@ -34,6 +34,7 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import java.util.stream.Stream;
@@ -912,6 +913,27 @@ public <T> T queryForObject(String sql, Class<T> requiredType, @Nullable Object.
 		return queryForObject(sql, args, getSingleColumnRowMapper(requiredType));
 	}
 
+	/**
+	 * Query with the specified SQL statement, RowMapper, and optional arguments,
+	 * returning the result as an Optional object. This method serves as a convenient substitution
+	 * for the boilerplate code typically required when using queryForObject, especially
+	 * to handle cases where the query result is empty.
+	 *
+	 * @param <T>       The type of the result objects.
+	 * @param sql       The SQL statement to be executed.
+	 * @param rowMapper The RowMapper implementation to map the query results to objects of type T.
+	 * @param args      Optional arguments to be bound to the SQL statement.
+	 * @return An Optional containing the first result of the query, or an empty Optional if the
+	 *         query produced no results.
+	 * @throws DataAccessException If an error occurs while accessing the data source.
+	 *
+	 * @see RowMapper
+	 * @see Optional
+	 */
+	public <T> Optional<T> queryForOptional(String sql, RowMapper<T> rowMapper, @Nullable Object... args) throws DataAccessException {
+		return query(sql, rowMapper, args).stream().findFirst();
+	}
+
 	@Override
 	public Map<String, Object> queryForMap(String sql, Object[] args, int[] argTypes) throws DataAccessException {
 		return result(queryForObject(sql, args, argTypes, getColumnMapRowMapper()));
diff --git a/spring-jdbc/src/test/java/org/springframework/jdbc/core/JdbcTemplateQueryTests.java b/spring-jdbc/src/test/java/org/springframework/jdbc/core/JdbcTemplateQueryTests.java
index 24da6eeb6718..864747fcdb63 100644
--- a/spring-jdbc/src/test/java/org/springframework/jdbc/core/JdbcTemplateQueryTests.java
+++ b/spring-jdbc/src/test/java/org/springframework/jdbc/core/JdbcTemplateQueryTests.java
@@ -25,6 +25,7 @@
 import java.sql.Statement;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Stream;
 
@@ -436,4 +437,36 @@ public void testQueryForLongWithArgs() throws Exception {
 		verify(this.connection).close();
 	}
 
+	@Test
+	public void testQueryForOptionalWithArgsAndRowMapper() throws Exception {
+		String sql = "SELECT AGE FROM CUSTMR WHERE ID = ?";
+		given(this.resultSet.next()).willReturn(true, false);
+		given(this.resultSet.getLong(1)).willReturn(87L);
+
+		Optional<Long> optionalResult = this.template.queryForOptional(sql, (rs, rowNum) -> rs.getLong(1), 1);
+
+		assertThat(optionalResult).as("Optional result").isPresent();
+		assertThat(optionalResult.get()).as("Correct result value").isEqualTo(87L);
+
+		verify(this.preparedStatement).setObject(1, 1);
+		verify(this.resultSet).close();
+		verify(this.preparedStatement).close();
+		verify(this.connection).close();
+	}
+
+	@Test
+	public void testQueryForOptionalWithArgsAndRowMapperEmptyResult() throws Exception {
+		String sql = "SELECT AGE FROM CUSTMR WHERE ID = ?";
+		given(this.resultSet.next()).willReturn(false);
+
+		Optional<Long> optionalResult = this.template.queryForOptional(sql, (rs, rowNum) -> rs.getLong(1), 2);
+
+		assertThat(optionalResult).as("Optional result").isEmpty();
+
+		verify(this.preparedStatement).setObject(1, 2);
+		verify(this.resultSet).close();
+		verify(this.preparedStatement).close();
+		verify(this.connection).close();
+	}
+
 }