I'm trying to use the MvvmCross Messenger plugin, but I simple get it to work.. it always return a "Null Reference Exception".
Here is the BaseViewModel I created to test it:
namespace TestProject.Core.ViewModels
{
public class BaseViewModel : MvxViewModel
{
private readonly IMvxMessenger _messenger;
public BaseViewModel(IMvxMessenger messenger)
{
messenger = _messenger;
}
public IMvxCommand TestMessageCommand
{
get { return new MvxCommand(DoTestMessage); }
}
private void DoTestMessage()
{
var message = new TestMessage(this, "Potato");
_messenger.Publish(message);
}
}
}
Here is the other ViewModel that should receive the message:
namespace TestProject.Core.ViewModels
{
public class HomeViewModel : MvxViewModel
{
private string _testMessage = string.Empty;
private readonly MvxSubscriptionToken _token;
public HomeViewModel(IMvxMessenger messenger)
{
_token = messenger.Subscribe<TestMessage>(OnTestMessage);
}
private void OnTestMessage(OnTestMessage testMessage)
{
_testMessage = testMessage.Result;
}
public ICommand ShowBasePageCommand
{
get { return new MvxCommand(() => ShowViewModel<BaseViewModel>()); }
}
}
}
And finally, here is the message:
namespace TestProject.Core.Messages
{
public class TestMessage
: MvxMessage
{
public QRCodeResultMessage(object sender, string result) : base(sender)
{
Result = result;
}
public string Result { get; private set; }
}
}
I bound a button on the HomePage to the "ShowBasePageCommand", and on the BasePage there is another button bound to the "TestMessageCommand".
Full Exception:
System.NullReferenceException: Object reference not set to an nstance of an object.
at TestProject.Core.ViewModels.BaseViewModel.DoTestMessage () [0x00014] in /Users/diegopatrocinio/Projects/Xamarin/TestProject/TestProject.Core/ViewModels/BaseViewModel.cs:49
at MvvmCross.Core.ViewModels.MvxCommand.Execute (System.Object parameter) [0x00009] in <69bce0378e8e413982d3b552d7e387a8>:0
at Xamarin.Forms.Button.Xamarin.Forms.IButtonController.SendClicked () [0x0000a] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Core\Button.cs:121
at Xamarin.Forms.Platform.Android.ButtonRenderer+ButtonClickListener.OnClick (Android.Views.View v) [0x0000f] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\Renderers\ButtonRenderer.cs:303
at Android.Views.View+IOnClickListenerInvoker.n_OnClick_Landroid_view_View_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_v) [0x00011] in /Users/builder/data/lanes/4009/3a62f1ea/source/monodroid/src/Mono.Android/platforms/android-25/src/generated/Android.Views.View.cs:1857
at at (wrapper dynamic-method) System.Object:1b16fb3a-f768-4a9f-8e2e-60f0085ed7fb (intptr,intptr,intptr)
Stack:
System.Diagnostics.Debugger.Mono_UnhandledException_internal() in
System.Diagnostics.Debugger.Mono_UnhandledException(System.NullReferenceException ex) in /Users/builder/data/lanes/4009/3a62f1ea/source/mono/mcs/class/corlib/System.Diagnostics/Debugger.cs:122
object.1b16fb3a-f768-4a9f-8e2e-60f0085ed7fb( arg0, arg1, arg2) in
TestProject.Core.ViewModels.BaseViewModel.DoTestMessage() in /Users/diegopatrocinio/Projects/Xamarin/TestProject/TestProject.Core/ViewModels/BaseViewModel.cs:49
Please note that your constructor has inverted the parameter and the class member:
public BaseViewModel(IMvxMessenger messenger)
{
messenger = _messenger;
}
Should be
public BaseViewModel(IMvxMessenger messenger)
{
_messenger = messenger;
}
Related
I am using aspnetboilerplate template
i have a student service class. i am getting a student profile List from stored procedure. how can i call a stored procedure in aspnetboilerplate template
public class StudentRepository : TabonoRepositoryBase<User, long>
{
private readonly IActiveTransactionProvider _transactionProvider;
public StudentRepository(IDbContextProvider<TabonoDbContext> dbContextProvider, IActiveTransactionProvider transactionProvider)
: base(dbContextProvider)
{
_transactionProvider = transactionProvider;
}
//TODO: Make async!
public async Task<int> GetProfileCompletePercentage(int studentid)
{
EnsureConnectionOpen();
using (var command = CreateCommand("Sp_GetStudentprofilepercentage", CommandType.StoredProcedure, new SqlParameter("StudentId", studentid)))
{
using (var dataReader = await command.ExecuteReaderAsync())
{
while (dataReader.Read())
{
return Convert.ToInt16(dataReader["TotalPer"].ToString());
}
return 0;
}
}
}
private DbCommand CreateCommand(string commandText, CommandType commandType, params SqlParameter[] parameters)
{
var command = Context.Database.GetDbConnection().CreateCommand();
command.CommandText = commandText;
command.CommandType = commandType;
command.Transaction = GetActiveTransaction();
foreach (var parameter in parameters)
{
command.Parameters.Add(parameter);
}
return command;
}
private void EnsureConnectionOpen()
{
var connection = Context.Database.GetDbConnection();
if (connection.State != ConnectionState.Open)
{
connection.Open();
}
}
private DbTransaction GetActiveTransaction()
{
return (DbTransaction)_transactionProvider.GetActiveTransaction(new ActiveTransactionProviderArgs
{
{"ContextType", typeof(TabonoDbContext) },
{"MultiTenancySide", MultiTenancySide }
});
}
}
And this is the service class
public class StudentService : AsyncCrudAppService<StudentCore, StudentDto, int, PagedResultRequestDto, StudentCreateDto, StudentUpdateDto>, IStudentService
{
public readonly IRepository<StudentCore> _studentRepository;
private readonly UserManager _userManager;
private readonly IStudentService _studentservice;
public StudentService(IRepository<StudentCore> repository, UserManager um, IStudentService studentservice) : base(repository)
{
_studentRepository = repository;
_userManager = um;
_studentservice = studentservice;
}
public Task GetProfileCompletePercentage(int studentid)
{
return _studentservice.GetProfileCompletePercentage(studentid);
}
}
Create an interface:
public interface IStudentRepository : IRepository<StudentCore>
{
Task<int> GetProfileCompletePercentage(int studentid);
}
Implement the interface:
public class StudentRepository : TabonoRepositoryBase<StudentCore>, IStudentRepository
{
// ...
}
Inject the interface and call the method:
public class StudentService : ...
{
private readonly IStudentRepository _studentRepository;
public StudentService(IStudentRepository repository) : base(repository)
{
_studentRepository = repository;
}
public Task GetProfileCompletePercentage(int studentid)
{
return _studentRepository.GetProfileCompletePercentage(studentid);
}
}
Note: StudentService must not inject IStudentService in constructor → infinite recursion!
For reference: https://www.codeproject.com/Articles/1199648/Using-Stored-Procedure-User-Defined-Function-and-V
I am working on an ASP.NET WebAPI using OWIN. To manage the instances of DBContext (Entity Framework), I try to use Ninject. However, when I call a controller, the programm returns an error:
The controller cannot be created, missing constructor.
Could you tell me what is going wrong here?
My Controller Class:
public class Testcontroller
{
private IApplicationDbContext _context;
public Testcontroller(IApplicationDbContext context)
{
_context = context;
}
}
This is the Ninject-File:
public static class NinjectWebCommon
{
private static readonly Bootstrapper bootstrapper = new Bootstrapper();
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}
public static void Stop()
{
bootstrapper.ShutDown();
}
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
try
{
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
kernel.Bind<IApplicationDbContext>().To<ApplicationDbContext>();
GlobalConfiguration.Configuration.DependencyResolver = new NinjectDependencyResolver(kernel);
RegisterServices(kernel);
return kernel;
}
catch
{
kernel.Dispose();
throw;
}
}
private static void RegisterServices(IKernel kernel)
{
}
}
Ninject Dependency Scope:
public class NinjectDependencyScope : IDependencyScope
{
IResolutionRoot resolver;
public NinjectDependencyScope(IResolutionRoot resolver)
{
this.resolver = resolver;
}
public object GetService(Type serviceType)
{
if (resolver == null)
throw new ObjectDisposedException("this", "This scope has been disposed");
return resolver.TryGet(serviceType);
}
public System.Collections.Generic.IEnumerable<object> GetServices(Type serviceType)
{
if (resolver == null)
throw new ObjectDisposedException("this", "This scope has been disposed");
return resolver.GetAll(serviceType);
}
public void Dispose()
{
IDisposable disposable = resolver as IDisposable;
if (disposable != null)
disposable.Dispose();
resolver = null;
}
}
// This class is the resolver, but it is also the global scope
// so we derive from NinjectScope.
public class NinjectDependencyResolver : NinjectDependencyScope, IDependencyResolver
{
IKernel kernel;
public NinjectDependencyResolver(IKernel kernel) : base(kernel)
{
this.kernel = kernel;
}
public IDependencyScope BeginScope()
{
return new NinjectDependencyScope(kernel.BeginBlock());
}
}
The Entity Framework DbContext-Class:
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IApplicationDbContext
{
public ApplicationDbContext()
: base("DefaultConnection", throwIfV1Schema: false)
{
Configuration.ProxyCreationEnabled = false;
Configuration.LazyLoadingEnabled = false;
}
public virtual DbSet<Models.Team> Teams { get; set; }
public static ApplicationDbContext Create()
{
return new ApplicationDbContext();
}
}
public interface IApplicationDbContext
{
DbSet<Models.Team> Teams { get; set; }
int SaveChanges();
Task<int> SaveChangesAsync(CancellationToken cancellationToken);
}
I tried to follow this tutorial: http://www.peterprovost.org/blog/2012/06/19/adding-ninject-to-web-api
What have I done wrong here?
Thanks in advance!
Unless there was a serious omission in you controller code, your controller is not inheriting from ApiController, as is expected with Web Api
public class TestController : ApiController {
private IApplicationDbContext _context;
public Testcontroller(IApplicationDbContext context) {
_context = context;
}
}
UPDATE
I tried to set up everything from scratch using this: http://www.alexzaitzev.pro/2014/11/webapi2-owin-and-ninject.html
For some reason, it now works out perfectly fine.
Thank you for your support!
In my case I need subscribe to TFS events (create/delete team project, workitem, checkin, iteration, areas) for realization some business logic. I based on this manual. Now I can catch only workitem and checkin events, but I need more (team project, iteration, areas). In this list, I did not find the right events.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using Microsoft.TeamFoundation.Common;
using Microsoft.TeamFoundation.Framework.Server;
using Microsoft.TeamFoundation.Integration.Server;
using Microsoft.TeamFoundation.VersionControl.Server;
using Microsoft.TeamFoundation.WorkItemTracking.Server;
public class WorkItemChangedEventHandler : ISubscriber
{
public string Name
{
get { return "WorkItemChangedEventHandler"; }
}
public SubscriberPriority Priority
{
get { return SubscriberPriority.Normal; }
}
public Type[] SubscribedTypes()
{
var types = new List<Type>
{
typeof(Microsoft.TeamFoundation.WorkItemTracking.Server.WorkItemChangedEvent),// working
typeof(Microsoft.TeamFoundation.VersionControl.Server.CheckinNotification),// working
typeof(Microsoft.TeamFoundation.Integration.Server.ProjectCreatedEvent)// NOT working
};
return types.ToArray();
}
public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType,
object notificationEventArgs, out int statusCode, out string statusMessage, out ExceptionPropertyCollection properties)
{
statusCode = 0;
properties = null;
statusMessage = String.Empty;
try
{
EventLog.WriteEntry("WorkItemChangedEventHandler", string.Format("Entity: {0} was modified", notificationEventArgs.GetType()));
}
catch (Exception ex)
{
EventLog.WriteEntry("WorkItemChangedEventHandler", ex.Message + ex.StackTrace);
}
return EventNotificationStatus.ActionPermitted;
}
}
I have one class for CheckinNotificationEventHandler:
public class CheckinNotificationEventHandler : ISubscriber
{
public Type[] SubscribedTypes()
{
return new Type[1] { typeof(CheckinNotification) };
}
public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType, object notificationEventArgs, out int statusCode, out string statusMessage, out ExceptionPropertyCollection properties)
{
if (notificationType == NotificationType.Notification && notificationEventArgs is CheckinNotification)
{
...
}
return EventNotificationStatus.ActionPermitted;
}
}
and a second class for WorkItemChangedEventHandler:
public class WorkItemChangedEventHandler : ISubscriber
{
public Type[] SubscribedTypes()
{
return new Type[1] { typeof(Microsoft.TeamFoundation.WorkItemTracking.Server.WorkItemChangedEvent) };
}
public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType, object notificationEventArgs, out int statusCode, out string statusMessage, out ExceptionPropertyCollection properties)
{
if (notificationType == NotificationType.Notification && notificationEventArgs is WorkItemChangedEvent)
{
...
}
return EventNotificationStatus.ActionPermitted;
}
}
IPlugin Calss Library
namespace IPlugin
{
public interface IPlugin
{
string Name { get; set; }
void Start();
void Stop();
}
[Export(typeof(IPlugin))]
public abstract class BasePlugin:IPlugin
{
private string _name;
public BasePlugin()
{
Name = "Base Plugin";
}
public string Name
{
get { return _name; }
set { _name = value; }
}
public virtual void Start()
{
fnDowWork();
}
protected abstract void fnDowWork();
public virtual void Stop()
{
}
}
}
Test Plugin Class Library
namespace TestPlugin
{
public class TestPlugin:IPlugin.BasePlugin
{
public TestPlugin()
{
Name = "Test Plugin";
}
protected override void fnDowWork()
{
Console.WriteLine("Do Work !");
}
}
}
Console Application
class Program
{
static void Main(string[] args)
{
var app = new MyApp();
foreach (var p in app._Plugins)
{
p.Start();
}
}
}
public class MyApp
{
[ImportMany(typeof(IPlugin.IPlugin))]
public IEnumerable<IPlugin.IPlugin> _Plugins;
public string _PluginFolder { get; set; }
public string _StartupPath { get; set; }
public MyApp()
{
_StartupPath = Environment.CurrentDirectory;
var pluginFolderName = System.Configuration.ConfigurationManager.AppSettings["PluginFolder"];
_PluginFolder = System.IO.Path.Combine(_StartupPath, pluginFolderName);
InitializeMEF();
}
private void InitializeMEF()
{
var dirCatalog = new DirectoryCatalog(_PluginFolder, "*.dll");
CompositionContainer container = new CompositionContainer(dirCatalog);
container.ComposeParts(this);
}
}
the DirectoryCatalog find tow Assembly IPlugin.dll and TestPlugin.dll and after Compose parts
the myApp._Plugins is not null but its empty , i don't know where i am doing wrong!
You will need to use the InheritedExportAttribute instead of the ExportAttribute:
[InheritedExport(typeof(IPlugin))]
public abstract class BasePlugin:IPlugin
Note that this will only work for plugins that derive from BasePlugin. Other implementations of IPlugin will not be marked for export. To do this you will have to decorate the interface instead.
We are using Caliburn Micro for the first time.
We have a AppBootstrapper inherited from ShellViewModel.
Situvation is that VieModels should have the same instance unless it is reset.
we are able to achieve shared or not shared everytime, but releasing the export whenever needed is still a mystery.
public class AppBootstrapper : Bootstrapper<ShellViewModel>
{
private static CompositionContainer _container;
protected override void Configure()
{
try
{
_container = new CompositionContainer(
new AggregateCatalog(AssemblySource.Instance.Select(x => new AssemblyCatalog(x))));
var batch = new CompositionBatch();
batch.AddExportedValue<IWindowManager>(new WindowManager());
batch.AddExportedValue<IEventAggregator>(new EventAggregator());
batch.AddExportedValue(_container);
StyleManager.ApplicationTheme = ThemeManager.FromName("Summer");
_container.Compose(batch);
}
catch (Exception exception)
{
}
}
public static void ReleaseAll()
{
}
protected override object GetInstance(Type serviceType, string key)
{
try
{
var contract = string.IsNullOrEmpty(key) ? AttributedModelServices.GetContractName(serviceType) : key;
var exports = _container.GetExportedValues<object>(contract);
if (exports.Any())
return exports.First();
throw new Exception(string.Format("Could not locate any instances of contract {0}.", contract));
}
catch (ReflectionTypeLoadException ex)
{
foreach (Exception inner in ex.LoaderExceptions)
{
// write details of "inner", in particular inner.Message
}
return null;
}
}
protected override IEnumerable<object> GetAllInstances(Type serviceType)
{
try
{
return _container.GetExportedValues<object>(AttributedModelServices.GetContractName(serviceType));
}
catch (Exception exception)
{
return null;
}
}
protected override void BuildUp(object instance)
{
_container.SatisfyImportsOnce(instance);
}
}
ShellViewModel
[Export(typeof(ShellViewModel))]
public sealed class ShellViewModel : Conductor<IScreen>.Collection.OneActive, IHandle<object>
{
[ImportingConstructor]
public ShellViewModel(CompositionContainer compositionContainer, IEventAggregator eventAggregator)
{
CompositionContainer = compositionContainer;
EventAggregator = eventAggregator;
eventAggregator.Subscribe(this);
Items.Add(compositionContainer.GetExportedValue<AViewModel>());
Items.Add(compositionContainer.GetExportedValue<BViewModel>());
ActivateItem(Items.Single(p => p.DisplayName == AppMessageType.A.ToString()));
}
public IEventAggregator EventAggregator { get; set; }
public CompositionContainer CompositionContainer { get; set; }
public void Handle(object message)
{
//throw new System.NotImplementedException();
}
public void B()
{
ActivateItem(Items.Single(p => p.DisplayName == AppMessageType.B.ToString()));
}
public void A()
{
ActivateItem(Items.Single(p => p.DisplayName == AppMessageType.A.ToString()));
}
public void RESET()
{
AppBootstrapper.ReleaseAll();
ActivateItem(Items.Single(p => p.DisplayName == AppMessageType.A.ToString()));
}
public enum AppMessageType
{
A,
B
}
}
AViewModel
[Export(typeof(AViewModel))]
public sealed class AViewModel : Conductor<IScreen>.Collection.OneActive, IHandle<object>
{
[ImportingConstructor]
public AViewModel(CompositionContainer compositionContainer, IEventAggregator eventAggregator)
{
DisplayName = ShellViewModel.AppMessageType.A.ToString();
CompositionContainer = compositionContainer;
EventAggregator = eventAggregator;
eventAggregator.Subscribe(this);
}
public IEventAggregator EventAggregator { get; set; }
public CompositionContainer CompositionContainer { get; set; }
public void Handle(object message)
{
//throw new System.NotImplementedException();
}
}
BViewModel
[Export(typeof(BViewModel))]
public sealed class BViewModel : Conductor<IScreen>.Collection.OneActive, IHandle<object>
{
[ImportingConstructor]
public BViewModel(CompositionContainer compositionContainer, IEventAggregator eventAggregator)
{
DisplayName = ShellViewModel.AppMessageType.B.ToString();
CompositionContainer = compositionContainer;
EventAggregator = eventAggregator;
eventAggregator.Subscribe(this);
}
public IEventAggregator EventAggregator { get; set; }
public CompositionContainer CompositionContainer { get; set; }
public void Handle(object message)
{
//throw new System.NotImplementedException();
}
}
Now AViewModel and BViewModel have single instance.
Whenever Release Button is clicked i want to have new instance of AViewModel and BViewModel.
Hoping to get a reply soon.
Regards,
Vivek
When working with an IoC container, the only part of your code that should take it as a dependency should be your composition root (i.e. your AppBootstrapper in this case). You shouldn't be injecting or referencing the container anywhere else in your code (except possibly factories).
If you want your ShellViewModel to control the lifetime of your child view models (A and B), then you should consider injecting view model factories into your ShellViewModel (via constructor injection if they are required dependencies).
Your AViewModelFactory would just have a single Create method that returns a new instance of AViewModel, likewise with the BViewModelFactory. You can simply new up your view models directly in the factories. If your view models have large dependency chains themselves, then you could consider adding a reference to your container in the factories, although preferably consider looking into the MEF ExportFactory<T> type.