flutter - Flutter Dart:错误_ImmutableMap <动态，动态>' is not a subtype of type ' Map

Question

我有这个代码

import "./HTTPMethod.dart";
import '../../DataModel/DataModel.dart';
mixin RouterMixin {
  HTTPMethod method;
  String scheme;
  String path;
  String baseURL;
  Map<String, dynamic> params;
  Map<String, String> headers;
}
class Router with RouterMixin {
  HTTPMethod method;
  String scheme;
  String path;
  String baseURL;
  Map<String, dynamic> params;
  Map<String, String> headers;
  Router._(this.method, this.path, this.scheme, this.baseURL, this.params,
      this.headers);
  // ignore: missing_return
  static Router getRouter(method, path,
      {scheme = "https://",
      baseURL = "xyz.com",
      params = const {},
      headers = const {
        "Accept": "application/json",
        "Content-Type": "application/json"
      }}) {
    var headerValue = Map<String, dynamic>.from(headers);
    DataModel.shared.authToken.then((value) {
      print("TOKEN: $value");
      if (value != null) {
        headerValue["Authorization"] = value;
      }
      final router =
          Router._(method, path, scheme, baseURL, params, headerValue);
      return router;
    }).catchError((error) {
      print("ROUTER: ${error.toString()}");
    });
  }
}

它给出了这个错误

flutter: type '_ImmutableMap<dynamic, dynamic>' is not a subtype of type 'Map<String, dynamic>'

即使我尝试简单

  static Router routerValue(method, path,
      {scheme = "https://",
      baseURL = "zyx.com",
      params = const {},
      headers = const {
        "Accept": "application/json",
        "Content-Type": "application/json"
      }}) {
    Router router = Router._(method, path, scheme, baseURL, params,
        {"Accept": "application/json", "Content-Type": "application/json"});
    return router;
    }

我给出了同样的错误。

Answer 1

您需要将params的默认值从const {}更改为const <String, dynamic>{}。您的getRouter函数应该返回Future<Router>而不是Router，因为您需要authToken的值，否则您的函数将不会返回任何内容。
我对您的代码进行了一些其他修改，您可以在此处看到:

abstract class RouterBase {
  HTTPMethod method;
  String scheme;
  String path;
  String baseURL;
  Map<String, dynamic> params;
  Map<String, dynamic> headers; // change to dynamic
}

class Router implements RouterBase {
  HTTPMethod method;
  String scheme;
  String path;
  String baseURL;
  Map<String, dynamic> params;
  Map<String, dynamic> headers;

  Router._(this.method, this.path, this.scheme, this.baseURL, this.params,
      this.headers);

  static Future<Router> getRouter(
    method,
    path, {
    scheme = "https://",
    baseURL = "xyz.com",
    params = const <String, dynamic>{}, // add generic types to fix your problem
    headers = const {
      "Accept": "application/json",
      "Content-Type": "application/json"
    },
  }) async {
    Map<String, dynamic> headerValue = HashMap<String, dynamic>.from(headers);
    var authToken = await DataModel.shared.authToken;
    if (authToken != null) {
      headerValue["Authorization"] = authToken;
    }
    return Router._(method, path, scheme, baseURL, params, headerValue);
  }
}