如何在飞镖中弄平一个嵌套的阵列？

Question

我如何弄平一个嵌套的阵列？

[
  {
    "page": 1,
    "items": [
      {
        "addresses": [
          "hello1",
          "hello2"
        ]
      }
    ]
  },
  {
    "page": 2,
    "items": [
      3,
      {
        "addresses": [
          "hello3",
          "hello4"
        ]
      }
    ]
  },
  {
    "page": 3,
    "items": [
      3,
      4
    ]
  }
];

所需的输出IST：

["hello1", "hello2", "hello3", "hello4"]

import 'dart:convert';

main() {
  const jsonString =
      '[{"page":1, "items": [{"addresses": ["hello1","hello2"]}]}, {"page":2, "items": [3, {"addresses": ["hello3","hello4"]}]}, {"page":3, "items": [3, 4]}]';
  final items = jsonDecode(jsonString) as List;
  final x = items.expand((p) => p["items"]).expand((p) => p["addresses"]);
  print(x);
}

Answer 1

好的，所以您有一个看起来像这样的地图列表：

{
  page: int,
  items: List<{
    addresses: List<String>
  }>

有时这些项目只是数字，您想在单个列表上获取所有地址，这就是我的方式：

List<String> result = [];

p.forEach((obj) {
  final objMap = obj as Map<String, dynamic>
  objMap['items'].forEach((item) {
    if (item is Map<String, dynamic>) {
      result.addAll(item['addresses'] as List<String>);
    }
  });
});

有点笨拙，我知道，但是我认为这会解决这个问题