decode nested prefixes in variant

lib/column/variant.go

@@ -307,6 +307,14 @@ func (c *Variant) decodeHeader(reader *proto.Reader) error {
 		return fmt.Errorf("unsupported variant discriminator version: %d", variantSerializationVersion)
 	}
 
+	for _, col := range c.columns {
+		if serialize, ok := col.(CustomSerialization); ok {
+			if err := serialize.ReadStatePrefix(reader); err != nil {
+				return fmt.Errorf("failed to read prefix for type %s in variant: %w", col.Type(), err)
+			}
+		}
+	}
+
 	return nil
 }
 

tests/json_test.go

@@ -31,8 +31,10 @@ func setupJSONTest(t *testing.T) driver.Conn {
 	SkipOnCloud(t, "cannot modify JSON settings on cloud")
 
 	conn, err := GetNativeConnection(clickhouse.Settings{
-		"max_execution_time":           60,
-		"allow_experimental_json_type": true,
+		"max_execution_time":              60,
+		"allow_experimental_variant_type": true,
+		"allow_experimental_dynamic_type": true,
+		"allow_experimental_json_type":    true,
 	}, nil, &clickhouse.Compression{
 		Method: clickhouse.CompressionLZ4,
 	})
@@ -415,3 +417,24 @@ func TestJSON_BatchFlush(t *testing.T) {
 		i++
 	}
 }
+
+// https://github.com/grafana/clickhouse-datasource/issues/1168
+func TestJSONArrayDynamic(t *testing.T) {
+	ctx := context.Background()
+	conn := setupJSONTest(t)
+
+	rows, err := conn.Query(ctx, `SELECT ['{"x":5}','{"y":6}']::Array(JSON)::Dynamic AS c`)
+	require.NoError(t, err)
+
+	require.True(t, rows.Next())
+}
+
+func TestJSONArrayVariant(t *testing.T) {
+	ctx := context.Background()
+	conn := setupJSONTest(t)
+
+	rows, err := conn.Query(ctx, `SELECT ['{"x":5}','{"y":6}']::Array(JSON)::Variant(Array(JSON)) AS c`)
+	require.NoError(t, err)
+
+	require.True(t, rows.Next())
+}