动态 ViewModel 导航

Question

我正在尝试找到一种方法来设置从 View 到我必须导航的 ViewModel。这是为了能够在不更改核心项目的情况下更改导航流程。

我认为更简单的方法是创建一个界面，在那里设置目标 ViewModel，然后将界面注入 ViewModel 以执行导航。

public interface IModelMapping
{
    MvxViewModel ViewModelToNavigate();
}

public class MyViewModel : MvxViewModel
{

    readonly IMvxNavigationService navigationService;
    readonly IModelMapping modelMapping;

    public MyViewModel(IMvxNavigationService navigationService, IModelMapping modelMapping)
    {
        this.navigationService = navigationService;
        this.modelMapping = modelMapping;
    }

    public IMvxAsyncCommand GoContent
    {
        get
        {
            IMvxViewModel vm = modelMapping.ViewModelToNavigate();
            IMvxAsyncCommand navigateCommand = new MvxAsyncCommand(() => navigationService.Navigate<vm>());

            return navigteCommand;
        }
    }
}

此代码的问题是我在设置 navigationService.Navigate() 时遇到错误。错误是 'vm is a variable but it is used like a type'

Answer 1

URI 导航和门面一起使用怎么样？另见 https://www.mvvmcross.com/documentation/fundamentals/navigation#uri-navigation

假设您正在构建一个任务应用程序，并且根据您想要显示不同视图的任务类型。这就是 NavigationFacades 派上用场的地方（正则表达式只能为您做这么多）。

mvx://task/?id=00 <– this task is done, show read-only view (ViewModelA)

mvx://task/?id=01 <– this task isn’t, go straight to edit view (ViewModelB)

[assembly: MvxRouting(typeof(SimpleNavigationFacade), @"mvx://task/\?id=(?<id>[A-Z0-9]{32})$")]
namespace *.NavigationFacades
{
    public class SimpleNavigationFacade
        : IMvxNavigationFacade
    {
        public Task<MvxViewModelRequest> BuildViewModelRequest(string url,
            IDictionary<string, string> currentParameters, MvxRequestedBy requestedBy)
        {
            // you can load data from a database etc.
            // try not to do a lot of work here, as the user is waiting for the UI to do something ;)
            var viewModelType = currentParameters["id"] == Guid.Empty.ToString("N") ? typeof(ViewModelA) : typeof(ViewModelB);

            return Task.FromResult(new MvxViewModelRequest(viewModelType, new MvxBundle(), null, requestedBy));
        }
    }
}

动态 ViewModel 导航

Dynamic ViewModel navigation

mvvmcross

xamarin