C# 在mvvmcross中从一个viewmodel导航到另一个viewmodel时崩溃
我想使用mvvmcross中的viewmodels从一个屏幕移动到下一个屏幕，并将一些模型传递到下一个ViewModel。但我遇到了以下问题： MvvmCross.Platform.Exceptions.MvxException:无法从定位器MvxDefaultViewModelLocator为类型iManage.ViewModels.LoginViewModel构造和初始化ViewModel-有关详细信息，请检查InnerException-->MvvmCross.Platform.Exceptions.MvxException:创建LoginViewModel类型的ViewModel时出现问题--->MvvmCross.Platform.Exceptions.MvxIoCResolveException:创建iManager.ViewModels.LoginViewModel时未能解析SchoolModel类型的参数项的参数 在MvvmCross.Platform.IoC.MvxSimpleIoCContainer.GetIoCParameterValues处（System.Type类型、System.Reflection.ConstructorInfo firstConstructor）[0x00066]输入：0 在：0中的MvvmCross.Platform.IoC.MvxSimpleIoCContainer.IoCConstruct（System.Type类型）[0x0002c]处 在MvvmCross.Platform.Mvx.IocConstruct（System.Type t）[0x00006]中：0 在MvvmCross.Core.ViewModels.MvxDefaultViewModelLocator.Load（System.Type viewModelType、MvvmCross.Core.ViewModels.IMvxBundle参数值、MvvmCross.Core.ViewModels.IMvxBundle保存状态）[0x00000]中：0 ---内部异常堆栈跟踪的结束--- 在MvvmCross.Core.ViewModels.MvxDefaultViewModelLocator.Load（System.Type viewModelType、MvvmCross.Core.ViewModels.IMvxBundle参数值、MvvmCross.Core.ViewModels.IMvxBundle保存状态）[0x00029]中：0 在MvvmCross.Core.ViewModels.MVXViewModelLoadLoadViewModel（MvvmCross.Core.ViewModels.MvxViewModelRequest请求，MvvmCross.Core.ViewModels.IMvxBundle保存状态）[0x00035]中：0 ---内部异常堆栈跟踪的结束--- 在MvvmCross.Core.ViewModels.MVXViewModelLoadLoadViewModel（MvvmCross.Core.ViewModels.MvxViewModelRequest请求，MvvmCross.Core.ViewModels.IMvxBundle保存状态）[0x00068]中：0 在MvvmCross.iOS.Views.MVXViewController ExtensionMethods.LoadViewModel（MvvmCross.iOS.Views.IMvxIosView iosView）[0x0005f]中：0 在MvvmCross.Core.Views.MvxViewExtensionMethods.OnViewCreate（MvvmCross.Core.Views.IMvxView视图，System.Func`1[TResult]viewModelLoader）[0x00012]中：0 在MvvmCross.iOS.Views.MVXViewController ExtensionMethods.OnViewCreate（MvvmCross.iOS.Views.IMvxIosView iosView）[0x00001]中：0 在MvvmCross.iOS.Views.MVXViewController适配器.HandleviewIDLoadCalled处（System.Object sender，System.EventArgs e）[0x00007]输入：0 at（包装器委托调用）：调用\u void\u object\u EventArgs（对象，System.EventArgs） 在：0中的MvvmCross.Platform.Core.MvxDelegateExtensionMethods.Rise（System.EventHandler，System.Object sender）[0x00003]处 在：0中的MvvmCross.Platform.iOS.Views.MvxEventSourceViewController.ViewDidLoad（）[0x00006]处 在MvvmCross.iOS.Views.MvxViewController.ViewDidLoad（）[0x00001]中：0 在/Users/pankajsachdeva/Projects/iManage/iOS/Views/LoginView.viewdiload（）[0x00001]中的iManage.iOS.Views.LoginView:18 在（包装器管理为本机）UIKit.UIApplication:UIApplicationMain（int，string[]，intptr，intptr） 在/Users/builder/data/lanes/5665/f70a1348/source/xamarin macios/src/UIKit/UIApplication.cs:79中的UIKit.UIApplication.Main（System.String[]args，System.IntPtr principal，System.IntPtr delegate）[0x00005] 在/Users/builder/data/lanes/5665/f70a1348/source/xamarin macios/src/UIKit/UIApplication.cs:63中的UIKit.UIApplication.Main（System.String[]args，System.String principalClassName，System.String delegateClassName）[0x00038]处 在/Users/pankajsachdeva/Projects/iManage/iOS/Main.cs:17中的iManage.iOS.Application.Main（System.String[]args）[0x00001] 从ViewModel代码：C# 在mvvmcross中从一个viewmodel导航到另一个viewmodel时崩溃,c#,xamarin,mvvm,xamarin.ios,mvvmcross,C#,Xamarin,Mvvm,Xamarin.ios,Mvvmcross,我想使用mvvmcross中的viewmodels从一个屏幕移动到下一个屏幕，并将一些模型传递到下一个ViewModel。但我遇到了以下问题： MvvmCross.Platform.Exceptions.MvxException:无法从定位器MvxDefaultViewModelLocator为类型iManage.ViewModels.LoginViewModel构造和初始化ViewModel-有关详细信息，请检查InnerException-->MvvmCross.Platform.Excep
public class SchoolSelectionViewModel : BaseViewModel
{
private readonly ISchoolNames _schoolService;
public SchoolSelectionViewModel(ISchoolNames schoolService)
{
_schoolService = schoolService;
}
public override void Start()
{
IsLoading = true;
_schoolService.GetFeedItems(OnDilbertItems, OnError);
}
private void OnDilbertItems(List<SchoolModel> list)
{
IsLoading = false;
Items = list;
}
private void OnError(Exception error)
{
// not reported for now
IsLoading = false;
}
private List<SchoolModel> _items = new List<SchoolModel>();
public List<SchoolModel> Items
{
get { return _items; }
set { _items = value; RaisePropertyChanged(() => Items); }
}
private MvxCommand<SchoolModel> _itemSelectedCommand;
public ICommand ItemSelectedCommand
{
get
{
_itemSelectedCommand = _itemSelectedCommand ?? new MvvmCross.Core.ViewModels.MvxCommand<SchoolModel>(DoSelectItem);
return _itemSelectedCommand;
}
}
private void DoSelectItem(SchoolModel item)
{
//ShowViewModel<LoginViewModel>(item);
ShowViewModel<LoginViewModel>(new LoginViewModel(item));
}
}
public class LoginViewModel : BaseViewModel
{
private readonly ILoginService _loginService;
private readonly IDialogService _dialogService;
public LoginViewModel(SchoolModel item)
{
//_loginService = loginService;
//_dialogService = dialogService;
School = item;
Username = "TestUser";
Password = "YouCantSeeMe";
IsLoading = false;
}
private SchoolModel _school;
public SchoolModel School
{
get
{
return _school;
}
set
{
SetProperty(ref _school, value);
RaisePropertyChanged(() => School);
}
}
private string _username;
public string Username
{
get
{
return _username;
}
set
{
SetProperty(ref _username, value);
RaisePropertyChanged(() => Username);
}
}
private string _password;
public string Password
{
get
{
return _password;
}
set
{
SetProperty(ref _password, value);
RaisePropertyChanged(() => Password);
}
}
private IMvxCommand _loginCommand;
public virtual IMvxCommand LoginCommand
{
get
{
_loginCommand = _loginCommand ?? new MvxCommand(AttemptLogin, CanExecuteLogin);
return _loginCommand;
}
}
private void AttemptLogin()
{
if (_loginService.Login(Username, Password))
{
ShowViewModel<DashboardStdViewModel>();
}
else
{
_dialogService.Alert("We were unable to log you in!", "Login Failed", "OK");
}
}
private bool CanExecuteLogin()
{
return (!string.IsNullOrEmpty(Username) || !string.IsNullOrWhiteSpace(Username))
&& (!string.IsNullOrEmpty(Password) || !string.IsNullOrWhiteSpace(Password));
}
}
公立学校选择ViewModel:BaseViewModel
{
私立只读学校名称学校服务；
公立学校选择视图模型（ISchoolNames学校服务）
{
_学校服务=学校服务；
}
公共覆盖无效开始（）
{
IsLoading=true；
_学校服务。GetFeedItems（OnDilbertItems，OnError）；
}
私有项目（列表）
{
IsLoading=false；
项目=列表；
}
私有void OnError（异常错误）
{
//目前还没有报道
IsLoading=false；
}
私有列表_items=新列表（）；
公共清单项目
{
获取{return\u items；}
设置{u items=value；RaisePropertyChanged（（）=>items）；}
}
专用MvxCommand _itemSelectedCommand；
公共ICommand ItemSelectedCommand
{
得到
{
_itemSelectedCommand=\u itemSelectedCommand？？新建MvvmCross.Core.ViewModels.MvxCommand（DoSelectItem）；
返回_itemSelectedCommand；
}
}
私有项目（学校模型项目）
{
//ShowViewModel（项目）；
ShowViewModel（新登录视图模型（项目））；
}
}
public class SchoolSelectionViewModel : BaseViewModel
{
private readonly ISchoolNames _schoolService;
public SchoolSelectionViewModel(ISchoolNames schoolService)
{
_schoolService = schoolService;
}
public override void Start()
{
IsLoading = true;
_schoolService.GetFeedItems(OnDilbertItems, OnError);
}
private void OnDilbertItems(List<SchoolModel> list)
{
IsLoading = false;
Items = list;
}
private void OnError(Exception error)
{
// not reported for now
IsLoading = false;
}
private List<SchoolModel> _items = new List<SchoolModel>();
public List<SchoolModel> Items
{
get { return _items; }
set { _items = value; RaisePropertyChanged(() => Items); }
}
private MvxCommand<SchoolModel> _itemSelectedCommand;
public ICommand ItemSelectedCommand
{
get
{
_itemSelectedCommand = _itemSelectedCommand ?? new MvvmCross.Core.ViewModels.MvxCommand<SchoolModel>(DoSelectItem);
return _itemSelectedCommand;
}
}
private void DoSelectItem(SchoolModel item)
{
//ShowViewModel<LoginViewModel>(item);
ShowViewModel<LoginViewModel>(new LoginViewModel(item));
}
}
public class LoginViewModel : BaseViewModel
{
private readonly ILoginService _loginService;
private readonly IDialogService _dialogService;
public LoginViewModel(SchoolModel item)
{
//_loginService = loginService;
//_dialogService = dialogService;
School = item;
Username = "TestUser";
Password = "YouCantSeeMe";
IsLoading = false;
}
private SchoolModel _school;
public SchoolModel School
{
get
{
return _school;
}
set
{
SetProperty(ref _school, value);
RaisePropertyChanged(() => School);
}
}
private string _username;
public string Username
{
get
{
return _username;
}
set
{
SetProperty(ref _username, value);
RaisePropertyChanged(() => Username);
}
}
private string _password;
public string Password
{
get
{
return _password;
}
set
{
SetProperty(ref _password, value);
RaisePropertyChanged(() => Password);
}
}
private IMvxCommand _loginCommand;
public virtual IMvxCommand LoginCommand
{
get
{
_loginCommand = _loginCommand ?? new MvxCommand(AttemptLogin, CanExecuteLogin);
return _loginCommand;
}
}
private void AttemptLogin()
{
if (_loginService.Login(Username, Password))
{
ShowViewModel<DashboardStdViewModel>();
}
else
{
_dialogService.Alert("We were unable to log you in!", "Login Failed", "OK");
}
}
private bool CanExecuteLogin()
{
return (!string.IsNullOrEmpty(Username) || !string.IsNullOrWhiteSpace(Username))
&& (!string.IsNullOrEmpty(Password) || !string.IsNullOrWhiteSpace(Password));
}
}
public类LoginViewModel:BaseViewModel
{
专用只读ILoginService(U loginService)；
专用只读IDialogService(对话服务)；
公共登录视图模型（学校模型项）
{
//_loginService=loginService；
//_dialogService=dialogService；
学校=项目；
Username=“TestUser”；
Password=“YouCantSeeMe”；
IsLoading=false；
}
私立学校模式(学校),；
公立学校示范学校
{
得到
{
返回学校；
}
设置
{
SetProperty（参考学校，价值）；
RaiseProperty更改（（）=>学校）；
}
}
私有字符串\u用户名；
公共字符串用户名
{
得到
{
返回_用户名；
}
设置
{
SetProperty（参考用户名、值）；
RaisePropertyChanged（（）=>用户名）；
}
}
私有字符串\u密码；
公共字符串密码
{
得到
{
返回密码；
}
Mvx.ConstructAndRegisterSingleton<IFoo, Foo>();
public class MyViewModel : MvxViewModel
{
private readonly IMvxNavigationService _navigationService;
public MyViewModel(IMvxNavigationService navigationService)
{
_navigationService = navigationService;
}
public async Task SomeMethod()
{
await _navigationService.Navigate<NextViewModel, MyObject>(new MyObject());
}
}
public class NextViewModel : MvxViewModel<MyObject>
{
private MyObject _myObject;
public override void Prepare(MyObject parameter)
{
// receive and store the parameter here
_myObject = parameter;
}
}
public class SchoolSelectionViewModel : BaseViewModel
{
public void DoSelectItem(SchoolModel item)
{
ShowViewModel<LoginViewModel, SchoolModel>(item);
}
}
public class LoginViewModel : BaseViewModel<SchoolModel>
{
private SchoolModel _parameter;
public override Task Prepare(SchoolModel parameter)
{
// receive and store the parameter here
_parameter = parameter;
}
}
public abstract class BaseViewModel<TParameter> : BaseViewModel, IMvxViewModel<TParameter>
{
public async Task Init(string parameter)
{
if (!string.IsNullOrEmpty(parameter))
{
IMvxJsonConverter serializer;
if (!Mvx.TryResolve(out serializer))
{
throw new MvxIoCResolveException("There is no implementation of IMvxJsonConverter registered. You need to use the MvvmCross Json plugin or create your own implementation of IMvxJsonConverter.");
}
var deserialized = serializer.DeserializeObject<TParameter>(parameter);
Prepare(deserialized);
await Initialize();
}
}
public abstract void Prepare(TParameter parameter);
}
public class SchoolSelectionViewModel : BaseViewModel
{
public void DoSelectItem(SchoolModel item)
{
ShowViewModel<LoginViewModel>(item);
}
}
public class LoginViewModel : BaseViewModel
{
private SchoolModel _parameter;
public override void Init(SchoolModel parameter)
{
// receive and store the parameter here
_parameter = parameter;
}
}