flutter - 如何在 flutter 中显示有条件的列表？

Question

我有一个列表，显示从数据库中选择的所有数据。现在我想实现一个条件来仅选择和显示当前 DateTime 的数据列表。

示例:显示一个列表，其中 List.year = DateTime().year。

我应该如何编写代码来制作这样的东西？

class CustomListView extends StatelessWidget {

  final List<Spacecraft> spacecrafts;

  CustomListView(this.spacecrafts);

  Widget build(context) {

  return ListView.builder(

     itemCount: spacecrafts.length,

     itemBuilder: (context, int currentIndex) {

      return createViewItem(spacecrafts[currentIndex], context);

     },
   ); 
  }

   Widget createViewItem(Spacecraft spacecraft, BuildContext context) {

        var itemDate = spacecraft.startDate;
        var currentDate =  new DateTime.now() ;

        return new ListTile(
                       .....

Answer 1

您必须过滤列表，无论是从数据库中获取列表还是使用 where，如下所示:

class FilteredListView extends StatelessWidget {
  final int year;
  final List<Spacecraft> filteredSpacecrafts;

  CustomListView(List<Spacecraft> allSpacecrafts, this.year) : 
    filteredSpacecrafts = allSpacecrafts.where(
      (spacecraft) => spacecraft.year == year).toList();

  Widget build(context) {

  return ListView.builder(

     itemCount: filteredSpacecrafts.length,

     itemBuilder: (context, int currentIndex) {

      return createViewItem(filteredSpacecrafts[currentIndex], context);

     },
   ); 
  }
...