From f82169130826c0b12981eeb352d6a24074cb2a46 Mon Sep 17 00:00:00 2001
From: DmitriyMX <dimon550@gmail.com>
Date: Sun, 3 Jan 2021 16:07:40 +0300
Subject: [PATCH] JdbcTemplate: add queryOne method

---
 src/main/java/ghast/database/JdbcOperations.java   |  3 +++
 src/main/java/ghast/database/JdbcTemplate.java     | 11 +++++++++++
 src/test/java/ghast/database/JdbcTemplateTest.java | 12 ++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/src/main/java/ghast/database/JdbcOperations.java b/src/main/java/ghast/database/JdbcOperations.java
index 9d70f56..6a4aa50 100644
--- a/src/main/java/ghast/database/JdbcOperations.java
+++ b/src/main/java/ghast/database/JdbcOperations.java
@@ -2,6 +2,7 @@ package ghast.database;
 
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 public interface JdbcOperations {
 
@@ -9,6 +10,8 @@ public interface JdbcOperations {
 
 	<T> T query(String sql, ResultSetExtractor<T> rse) throws DataAccessException;
 
+	<T> Optional<T> queryOne(String sql, ResultSetExtractor<T> rse) throws DataAccessException;
+
 	<T> List<T> queryList(String sql, RowMapper<T> rowMapper) throws DataAccessException;
 
 	Map<String, Object> queryForMap(String sql) throws DataAccessException;
diff --git a/src/main/java/ghast/database/JdbcTemplate.java b/src/main/java/ghast/database/JdbcTemplate.java
index 52ed3a4..3b91032 100644
--- a/src/main/java/ghast/database/JdbcTemplate.java
+++ b/src/main/java/ghast/database/JdbcTemplate.java
@@ -59,6 +59,17 @@ public class JdbcTemplate implements JdbcOperations {
 		}
 	}
 
+	@Override
+	public <T> Optional<T> queryOne(String sql, ResultSetExtractor<T> rse) throws DataAccessException {
+		return query(sql, rs -> {
+			if (rs.next()) {
+				return Optional.ofNullable(rse.extractData(rs));
+			} else {
+				return Optional.empty();
+			}
+		});
+	}
+
 	@Override
 	public <T> List<T> queryList(String sql, final RowMapper<T> rowMapper) throws DataAccessException {
 		return query(sql, rs -> {
diff --git a/src/test/java/ghast/database/JdbcTemplateTest.java b/src/test/java/ghast/database/JdbcTemplateTest.java
index bbdc8bc..97a3f97 100644
--- a/src/test/java/ghast/database/JdbcTemplateTest.java
+++ b/src/test/java/ghast/database/JdbcTemplateTest.java
@@ -17,6 +17,7 @@ import java.sql.SQLException;
 import java.text.MessageFormat;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.StringJoiner;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
@@ -99,6 +100,17 @@ class JdbcTemplateTest {
 		assertEquals(DATA[0][1], value);
 	}
 
+	@Test
+	void testQuery_Simple_Optional() {
+		String sql = MessageFormat.format("SELECT {2} FROM {0} WHERE {1} LIKE ''{3}''",
+				TABLE_NAME, COLUMN_NAME, COLUMN_VALUE, DATA[0][0]);
+
+		Optional<Integer> optValue = jdbcTemplate.queryOne(sql, rs -> rs.getInt(1));
+
+		assertTrue(optValue.isPresent());
+		assertEquals(DATA[0][1], optValue.get());
+	}
+
 	@Test
 	void testQuery_Simple_List() {
 		String sql = MessageFormat.format("SELECT {2} FROM {0} WHERE {1} LIKE ''{3}'' OR {1} LIKE ''{4}''",