search_tab.dart

class _SearchTabState extends State<SearchTab> {
  TextEditingController _controller;
  FocusNode _focusNode;
  String _terms = '';

  @override
  void initState() {
    super.initState();
    _controller = TextEditingController()..addListener(_onTextChanged);
    _focusNode = FocusNode();
  }

  @override
  void dispose() {
    _focusNode.dispose();
    _controller.dispose();
    super.dispose();
  }

  void _onTextChanged() {
    setState(() {
      _terms = _controller.text;
    });
  }

  Widget _buildSearchBox() {
    return Padding(
      padding: const EdgeInsets.all(8),
      child: SearchBar(
        controller: _controller,
        focusNode: _focusNode,
      ),
    );
  }                                     // TO HERE

 @override
 Widget build(BuildContext context) {