关于为什么我无法构建这个冻结的（颤振/飞镖）示例（使用泛型）有什么想法吗？答案

【问题标题】：Any thoughts on why I cannot get this freezed (flutter/dart) example (with generics) to build?关于为什么我无法构建这个冻结的（颤振/飞镖）示例（使用泛型）有什么想法吗？
【发布时间】：2022-08-18 03:02:26
【问题描述】：

我是扑扑和飞镖的新手。我试图让以下示例在我的测试项目中工作：

https://pub.dev/packages/freezed#deserializing-generic-classes

这是我的整个飞镖文件（api_response.dart）：

import \'package:freezed_annotation/freezed_annotation.dart\';
import \'package:flutter/foundation.dart\';

part \'api_response.freezed.dart\';
part \'api_response.g.dart\';

@Freezed(genericArgumentFactories: true)
class ApiResponse<T> with _$ApiResponse {
  const factory ApiResponse<T>.data(T data) = ApiResponseData;
  const factory ApiResponse<T>.error(String message) = ApiResponseError;

  factory ApiResponse<T>.fromJson(Map<String, dynamic> json, T Function(Object?) fromJsonT) => _$ApiResponseFromJson(json, fromJsonT);
}

当我使用此命令构建时：

flutter pub run build_runner build --delete-conflicting-outputs

我收到以下错误：

[INFO] Running build...
[SEVERE] freezed:freezed on lib/models/api_response.dart:

This builder requires Dart inputs without syntax errors.
However, package:psf_provider/models/api_response.dart (or an existing part) contains the following errors.
api_response.dart:9:32: Functions must have an explicit list of parameters.
api_response.dart:9:3: Only redirecting factory constructors can be declared to be \'const\'.
api_response.dart:9:32: A function body must be provided.
And 13 more...

这是我的 pubspec.yaml 文件定义，用于显示我正在使用的版本：

environment:
  sdk: \">=2.17.0 <3.0.0\"

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.2
  flutter_hooks: ^0.18.0
  hooks_riverpod: ^2.0.0-dev.9
  dio: ^4.0.0
  flutter_secure_storage: ^4.1.0
  easy_localization: ^3.0.1
  settings_ui: ^2.0.0
  freezed_annotation: ^2.1.0
  json_annotation: ^4.6.0

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_lints: ^1.0.0
  build_runner: ^2.2.0
  freezed: ^2.1.0+1
  json_serializable: ^6.3.1

有任何想法吗？感谢您的关注！

标签： flutter dart generics freezed

【解决方案1】：

看起来文档已经过时了。它应该如下所示：

@Freezed(genericArgumentFactories: true)
class ApiResponse<T> with _$ApiResponse<T> {
  factory ApiResponse.data(T data) = ApiResponseData;
  factory ApiResponse.error(String message) = ApiResponseError;

  factory ApiResponse.fromJson(
    Map<String, dynamic> json,
    T Function(Object? json) fromJsonT,
  ) =>
      _$ApiResponseFromJson<T>(json, fromJsonT);
}

【讨论】：