fix: Fix Column Type Name for PostgreSQL ARRAY types

Author: sakthivelmanii

src/main/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaData.java

@@ -16,7 +16,9 @@
 
 package com.google.cloud.spanner.jdbc;
 
+import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.ResultSet;
+import com.google.cloud.spanner.Type;
 import com.google.cloud.spanner.connection.ConnectionProperties;
 import com.google.common.base.Preconditions;
 import java.sql.Connection;
@@ -192,7 +194,14 @@ public int getColumnType(int column) {
 
   @Override
   public String getColumnTypeName(int column) {
-    return spannerResultSet.getColumnType(column - 1).getCode().name();
+    Type columnType = spannerResultSet.getColumnType(column - 1);
+    if (columnType.getCode() == Type.Code.ARRAY && statement instanceof JdbcStatement) {
+      Dialect dialect = ((JdbcStatement) statement).getConnection().getDialect();
+      if (dialect == Dialect.POSTGRESQL) {
+        return "_" + columnType.getArrayElementType().getSpannerTypeName(dialect);
+      }
+    }
+    return columnType.getCode().name();
   }
 
   @Override

src/test/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaDataTest.java

@@ -18,11 +18,13 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import com.google.cloud.ByteArray;
+import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.ResultSet;
 import com.google.cloud.spanner.ResultSets;
 import com.google.cloud.spanner.Struct;
@@ -540,6 +542,34 @@ public void getColumnTypeName() {
     }
   }
 
+  @Test
+  public void getColumnTypeNameForPostgreSQL() throws SQLException {
+    JdbcConnection connection = mock(JdbcConnection.class);
+    JdbcStatement statement = mock(JdbcStatement.class);
+    JdbcResultSet resultSet = getFooTestResultSet(statement);
+    when(connection.getSchema()).thenReturn("");
+    when(connection.getCatalog()).thenReturn("test-database");
+    when(statement.getConnection()).then(new Returns(connection));
+    when(connection.getDialect()).thenReturn(Dialect.POSTGRESQL);
+
+    JdbcResultSetMetaData sub = resultSet.getMetaData();
+
+    int index = 1;
+    for (TestColumn col : TEST_COLUMNS) {
+      if (col.type.getCode() == Type.Code.ARRAY) {
+        String typeName = sub.getColumnTypeName(index);
+        assertNotNull(typeName);
+        assertEquals('_', typeName.charAt(0));
+        assertEquals(
+            col.type.getArrayElementType().getSpannerTypeName(Dialect.POSTGRESQL),
+            typeName.substring(1));
+      } else {
+        assertEquals(col.type.getCode().name(), sub.getColumnTypeName(index));
+      }
+      index++;
+    }
+  }
+
   @Test
   public void testIsReadOnly() {
     for (int i = 0; i < TEST_COLUMNS.size(); i++) {