flutter - Flutter:如果值为空或没有值，如何隐藏TableRow

Question

我有2个JSON情况，如下所示

情况1:“国家”的一个值是空的

[
  {
    "id": 1,
    "continent": "North America",
    "country": "United States"
  },
  {
    "id": 2,
    "continent": "Europe",
    "country": "Germany"
  },
  {
    "id": 3,
    "continent": "Asia",
    "country": null
  }
]

情况2:“国家”之一没有值(value)

[
  {
    "id": 1,
    "continent": "North America",
    "country": "United States"
  },
  {
    "id": 2,
    "continent": "Europe",
    "country": "Germany"
  },
  {
    "id": 3,
    "continent": "Asia"
  }
]

我使用 TableRow在 Table中显示“大陆”和“国家”，

TableRow(children: [
                      TableCell(child: Text(continent.continent)), 
                      TableCell(child: Text(continent.country))])

但是，如果List或 continent.country == null中没有“国家” =>我不想显示该 TableRow，那么请帮助我设置以下条件:

案例1

案例2

案例1 +案例2

这是主文件:

import 'package:ask/services/continent_services2.dart';
import 'package:flutter/material.dart';
import 'model/continent_model2.dart';

class TableRowDemo extends StatefulWidget {
  TableRowDemo() : super();

  @override
  _ContinentPageState createState() => _ContinentPageState();
}

class _ContinentPageState extends State<TableRowDemo> {
  List<Continent> _continent;

  @override
  void initState() {
    super.initState();

    ContinentServices2.getContinent().then((continents) {
      setState(() {
        _continent = continents;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('')),
      body: Column(
        children: <Widget>[
          for (Continent continent in _continent)
            SingleChildScrollView(
              child: Table(children: [
                continent.country == null
                    ? Container() // Error: type 'Container' is not a subtype of type 'TableRow'
                    : TableRow(children: [
                      TableCell(child: Text(continent.continent)),
                      TableCell(child: Text(continent.country))]),
              ]),
            ),
        ],
      ),
    );
  }
}

Answer 1

您应该将大洲重命名为“区域”或“区域”，并且可以使用简单的if条件:

(...)
Table(children: [
    for (Zone zone in zones)
        If (zone.country != null )
            TableRow(children[
                TableCell(child: Text(zone.continent)),
                TableCell(child: Text(zone.country)),
          ])
    )