fix(jdbc-v2): render array contents for named tuples

CHANGELOG.md

@@ -44,6 +44,8 @@
 
 ### Bug Fixes 
 
+- **[jdbc-v2]** Made JDBC `Array` values render their nested contents through `toString()`, including arrays of named tuples, so clients such as IDE database viewers no longer display the wrapper class name and identity hash. (https://github.com/ClickHouse/clickhouse-java/issues/3045)
+
 - **[client-v2]** Fixed LZ4 input streams not closing their underlying HTTP response stream. Closing an LZ4 stream
   returned by `QueryResponse.getInputStream()` now releases the wrapped transport stream, including after a partial
   read. (https://github.com/ClickHouse/clickhouse-java/issues/2985)

jdbc-v2/src/main/java/com/clickhouse/jdbc/types/Array.java

@@ -11,6 +11,7 @@
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.SQLFeatureNotSupportedException;
+import java.util.Arrays;
 import java.util.Map;
 
 public class Array implements java.sql.Array {
@@ -127,6 +128,16 @@ private void ensureValid() throws SQLException {
         }
     }
 
+    /**
+     * Returns a readable representation of the array contents. JDBC clients such as IDE database viewers
+     * commonly use {@code toString()} when rendering values returned by {@link java.sql.ResultSet#getObject}.
+     * Deep formatting is required for arrays of tuples and nested arrays.
+     */
+    @Override
+    public String toString() {
+        return Arrays.deepToString(array);
+    }
+
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {

jdbc-v2/src/test/java/com/clickhouse/jdbc/ArrayTupleIntegrationTest.java

@@ -0,0 +1,43 @@
+package com.clickhouse.jdbc;
+
+import org.testng.annotations.Test;
+
+import java.sql.Array;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Arrays;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertFalse;
+import static org.testng.Assert.assertTrue;
+
+public class ArrayTupleIntegrationTest extends JdbcIntegrationTest {
+
+    @Test(groups = {"integration"})
+    public void testArrayOfNamedAndUnnamedTuplesToString() throws Exception {
+        String uuid = "550e8400-e29b-41d4-a716-446655440000";
+        String expected = "[[" + uuid + "]]";
+        String query = "SELECT [('" + uuid + "')::Tuple(id UUID)] AS named, "
+                + "[('" + uuid + "')::Tuple(UUID)] AS unnamed";
+
+        try (Connection connection = getJdbcConnection();
+             Statement statement = connection.createStatement();
+             ResultSet resultSet = statement.executeQuery(query)) {
+            assertTrue(resultSet.next());
+
+            assertArrayValue(resultSet.getObject("named"), expected);
+            assertArrayValue(resultSet.getObject("unnamed"), expected);
+
+            assertFalse(resultSet.next());
+        }
+    }
+
+    private static void assertArrayValue(Object value, String expected) throws SQLException {
+        assertTrue(value instanceof Array);
+        Array array = (Array) value;
+        assertEquals(value.toString(), expected);
+        assertEquals(Arrays.deepToString((Object[]) array.getArray()), expected);
+    }
+}

jdbc-v2/src/test/java/com/clickhouse/jdbc/types/ArrayTest.java

@@ -0,0 +1,22 @@
+package com.clickhouse.jdbc.types;
+
+import com.clickhouse.data.ClickHouseColumn;
+import org.testng.annotations.Test;
+
+import java.sql.SQLException;
+import java.util.UUID;
+
+import static org.testng.Assert.assertEquals;
+
+@Test(groups = {"unit"})
+public class ArrayTest {
+
+    @Test
+    public void testToStringForArrayOfNamedTuples() throws SQLException {
+        ClickHouseColumn column = ClickHouseColumn.of("value", "Array(Tuple(id UUID))");
+        UUID id = UUID.fromString("550e8400-e29b-41d4-a716-446655440000");
+        Array array = new Array(column, new Object[] {new Object[] {id}});
+
+        assertEquals(array.toString(), "[[550e8400-e29b-41d4-a716-446655440000]]");
+    }
+}