Fix panic on nil map append (#1383)

Author: jkaflik

Diff for: lib/column/map.go

@@ -169,6 +169,15 @@ func (col *Map) Append(v any) (nulls []uint8, err error) {
 }
 
 func (col *Map) AppendRow(v any) error {
+	if v == nil {
+		return &ColumnConverterError{
+			Op:   "Append",
+			To:   string(col.chType),
+			From: fmt.Sprintf("%T", v),
+			Hint: fmt.Sprintf("try using %s", col.scanType),
+		}
+	}
+
 	value := reflect.Indirect(reflect.ValueOf(v))
 	if value.Type() == col.scanType {
 		var (

Diff for: tests/map_test.go

@@ -338,6 +338,31 @@ func TestOrderedMap(t *testing.T) {
 	require.Equal(t, 1000, i)
 }
 
+func TestInsertMapNil(t *testing.T) {
+	conn, err := GetNativeConnection(nil, nil, &clickhouse.Compression{
+		Method: clickhouse.CompressionLZ4,
+	})
+	ctx := context.Background()
+	require.NoError(t, err)
+	if !CheckMinServerServerVersion(conn, 21, 9, 0) {
+		t.Skip(fmt.Errorf("unsupported clickhouse version"))
+		return
+	}
+	const ddl = `
+		CREATE TABLE test_map_nil (
+			  Col1 Map(String, UInt64)
+		) Engine MergeTree() ORDER BY tuple()
+		`
+	defer func() {
+		conn.Exec(ctx, "DROP TABLE IF EXISTS test_map_nil")
+	}()
+	require.NoError(t, conn.Exec(ctx, ddl))
+	batch, err := conn.PrepareBatch(ctx, "INSERT INTO test_map_nil")
+	require.NoError(t, err)
+
+	assert.ErrorContains(t, batch.Append(nil), " converting <nil> to Map(String, UInt64) is unsupported")
+}
+
 type testMapSerializer struct {
 	val map[string]uint64
 }

Diff for: tests/std/map_test.go

@@ -98,3 +98,35 @@ func TestStdMap(t *testing.T) {
 		})
 	}
 }
+
+func TestStdInsertNilMap(t *testing.T) {
+	dsns := map[string]clickhouse.Protocol{"Native": clickhouse.Native, "Http": clickhouse.HTTP}
+	useSSL, err := strconv.ParseBool(clickhouse_tests.GetEnv("CLICKHOUSE_USE_SSL", "false"))
+	require.NoError(t, err)
+	for name, protocol := range dsns {
+		t.Run(fmt.Sprintf("%s Protocol", name), func(t *testing.T) {
+			conn, err := GetStdDSNConnection(protocol, useSSL, url.Values{})
+			require.NoError(t, err)
+			if !CheckMinServerVersion(conn, 21, 9, 0) {
+				t.Skip(fmt.Errorf("unsupported clickhouse version"))
+				return
+			}
+			const ddl = `
+		CREATE TABLE test_map_nil (
+			  Col1 Map(String, UInt64)
+		) Engine MergeTree() ORDER BY tuple()
+		`
+			defer func() {
+				conn.Exec("DROP TABLE test_map_nil")
+			}()
+			_, err = conn.Exec(ddl)
+			require.NoError(t, err)
+			scope, err := conn.Begin()
+			require.NoError(t, err)
+			batch, err := scope.Prepare("INSERT INTO test_map_nil")
+			require.NoError(t, err)
+			_, err = batch.Exec(nil)
+			assert.ErrorContains(t, err, " converting <nil> to Map(String, UInt64) is unsupported")
+		})
+	}
+}