how to find the return value from the map is empty

Question

im trying to create a listview with a search query, i want to show a empty icon when the return element form the map function is empty can any help me to achive this

ListView(
          children: controller.todo.value.where((element) {
        if (controller.search.value != '') {
          return element.labels!
                  .toString()
                  .toLowerCase()
                  .contains(controller.search.value);
        }
        return true;
      }).map((todo) {

      //here i need to check whether it is null or nor
      
      return Text(todo.name)}).toList())
           
            

Answer 1

Try this:

Builder(
  builder: (context) {
    List<Widget> children =
        controller.todo.value.where((element) {
      if (controller.search.value != '') {
        return element.labels!
            .toString()
            .toLowerCase()
            .contains(controller.search.value);
      }
      return true;
    }).map((todo) {
      return Text(todo.name);
    }).toList();

    return children.isEmpty
        ? Center(
            child: Icon(Icons.warning),
          )
        : ListView(
            children: children,
          );
  },
),