如何按字符串格式按日期对对象列表进行排序？

Question

我有一个列表，它有一个名为 updatedAt 的参数，它是一个具有 DateTime.now().toString().substring(0, 19) 的字符串，我需要按日期（最新（位置 0）到最旧（最后位置））组织，但是当我尝试使用 list.sort((a, b) => a.updatedAt.compareTo(b.updatedAt)) 时出现以下错误，我是否必须将字符串转换为 DateTime 或其他内容？

class Product {

  String id;
  String image;
  String name;
  String desc;
  int price;
  int quantity;
  String category;
  String createdAt;
  String updatedAt;
  bool active;

  Product({this.id, this.image, this.name, this.desc, this.price, this.quantity,
    this.category, this.createdAt, this.updatedAt, this.active}){
    quantity = 1;
    active = true;
  }

  Future<void> getProducts() async {

        List<Product> products = [];

        products.addAll(await getProductsFromFirestore()); // Here I add products from Firebase...

        print(products[0].updatedAt); // 2020-07-21 12:31:08
        print(products[1].updatedAt); // 2020-07-21 12:31:13
    
        products.sort((a, b) => a.updatedAt.compareTo(b.updatedAt));

  }

错误（Flutter Web）：

Error: Expected a value of type 'Comparable<dynamic>', but got one of type 'Product'
at Object.throw_ [as throw] (http://localhost:53122/dart_sdk.js:4339:11)
at Object.castError (http://localhost:53122/dart_sdk.js:4310:15)
at Object.cast [as as] (http://localhost:53122/dart_sdk.js:4626:17)
at Function.as_C [as as] (http://localhost:53122/dart_sdk.js:4271:19)
at http://localhost:53122/dart_sdk.js:15079:98
at Function._insertionSort (http://localhost:53122/dart_sdk.js:23099:55)
at Function._doSort (http://localhost:53122/dart_sdk.js:23086:24)
at Function.sort (http://localhost:53122/dart_sdk.js:23068:22)
at Array.[dartx.sort] (http://localhost:53122/dart_sdk.js:15079:26)
at RxList.new.sort (http://localhost:53122/packages/get/src/rx/rx_impl.dart.lib.js:610:27)
at home_controller.HomeController.new.getProductsFromController (http://localhost:53122/packages/site_catalogo_modelo/controllers/home_controller.dart.lib.js:94:21)
at product_controller.ProductController.new.getProducts (http://localhost:53122/packages/site_catalogo_modelo/controllers/home_controller.dart.lib.js:212:74)
at getProducts.next (<anonymous>)
at http://localhost:53122/dart_sdk.js:37340:33
at _RootZone.runUnary (http://localhost:53122/dart_sdk.js:37194:58)
at _FutureListener.thenAwait.handleValue (http://localhost:53122/dart_sdk.js:32178:29)
at handleValueCallback (http://localhost:53122/dart_sdk.js:32725:49)
at Function._propagateToListeners (http://localhost:53122/dart_sdk.js:32763:17)
at _Future.new.[_completeWithValue] (http://localhost:53122/dart_sdk.js:32606:23)
at async._AsyncCallbackEntry.new.callback (http://localhost:53122/dart_sdk.js:32628:35)
at Object._microtaskLoop (http://localhost:53122/dart_sdk.js:37455:13)
at _startMicrotaskLoop (http://localhost:53122/dart_sdk.js:37461:13)
at http://localhost:53122/dart_sdk.js:32980:9

Answer 1

问题是我没有使用 List，我使用 get package 进行状态管理，我的产品列表是一个可观察对象，它在另一个变量中包含 List itsefl，因此排序无效应该的，而且我不得不更改为 'b.updatedAt.compareTo(a.updatedAt))' 以按照我需要的顺序获取列表。

如何按字符串格式按日期对对象列表进行排序？

How to sort a List of Object by date in String format?

sorting

list

dart

flutter

flutter-web