c# - MVVM WPF - 登录逻辑

Question

我需要有关应用中身份验证属性的帮助。

Q1:我对一些模型的 JSON 进行了反序列化，因此在 ViewModel 中我有一个具有 idUser(来自服务器的响应)的模型。如何在不破坏 MVVM 架构的情况下在 FriendsViewModel 中使用该信息？

最好的问候， 安东尼

Answer 1

执行流程可能是这样的:

• 应用程序 View 模型启动(您的图表缺少此 View 模型)；
• 它使用登录 View 模型请求异步登录；
• 如果登录成功，则应用 View 模型创建通用 View 模型；
• 普通 View 模型加载 friend
• 如果登录失败，应用程序 View 模型会创建错误 View 模型。

示例代码(您可能想使用自己喜欢的 IoC 来创建 View 模型和注入(inject)服务):

public class ApplicationVm
{
    private readonly IInteractionService interactionService;
    private readonly IDataService dataService;

    private async Task LoadDataAsync()
    {
        try
        {
            // we need to ask for credentials
            var loginVm = new LoginVm();
            if (interactionService.ShowInDialog(loginVm) == true)
            {
                // performing login
                var userId = await dataService.LoginAsync(loginVm.UserName, loginVm.Password);
                // setting content to general view model, which is the payload of our app
                Content = new GeneralVm(userId, dataService);
            }
            else
            {
                // setting content to stub, which shows us "Login cancelled" message
                Content = new StubVm { Message = "Login cancelled" };
            }
        }
        catch (Exception ex)
        {
            // setting content to stub, which shows us "Login failed" message
            Content = new StubVm { Message = $"Login failed: {ex.Message}" };
        }
    }

    public ApplicationVm(IInteractionService interactionService, IDataService dataService)
    {
        this.interactionService = interactionService;
        this.dataService = dataService;
        var _ = LoadDataAsync();
    }

    public object Content { get; private set; }
}

public interface IInteractionService
{
    bool? ShowInDialog(object viewModel);
}

public interface IDataService
{
    Task<int> LoginAsync(string userName, string password);
    Task<IEnumerable<Friend>> GetFriendsAsync(int userId);
}

public class LoginVm
{
    public string UserName { get; set; }
    public string Password { get; set; }
}

public class GeneralVm
{
    private readonly int userId;
    private readonly IDataService dataService;

    private async Task LoadFriendsAsync()
    {
        var friends = await dataService.GetFriendsAsync(userId);
        Friends = friends
            .Select(model => new FriendVm(userId, model));
    }

    public GeneralVm(int userId, IDataService dataService)
    {
        this.userId = userId;
        this.dataService = dataService;
    }

    public IEnumerable<FriendVm> Friends { get; private set; }
}

public class FriendVm
{
    public FriendVm(int userId, Friend model)
    {
    }
}

public class Friend { }

public class StubVm
{
    public string Message { get; set; }
}