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how to perform a runtime view update when using ResourceViewLocationProvider

Im runing a nancyfx with owin on centos 6.5 with mono 5.10.0.140, I change the default ViewLocationProvider to ResourceViewLocationProvider for the default ViewLocationProvider causes memory leak of somekind after running for days, and the ResourceViewLocationProvider dont have the same problem. I would like to hot update Views just like what we can do with a default ViewLocationProvider, but it seems impossibe when googling around.
I did find a partial solution though, by implenting a custom IViewLocator and a IViewCache, I did achieve someking of hot update. But It didn`t feel right aside from those ugly static class
//Here is what I did in the custom IViewLocator
//...class definition fallback viewlocator and other staffs
private static ConcurrentDictionary<string, ViewLocationResult> _cachedViewLocationResults;
//..other code
public ViewLocationResult LocateView(string viewName, NancyContext context)
{
//...lock and others
if (_cachedViewLocationResults != null && _cachedViewLocationResults.ContainsKey(viewName))
{
return _cachedViewLocationResults[viewName];
}
//...lock and others
return fallbackViewLocator.LocateView(viewName, context);
}
//...other class
//here is how I update Views
public static void UpdateCachedView(IDictionary<string, ViewLocationResult> replacements)
{
lock (CacheLock)
{
if(_cachedViewLocationResults == null)_cachedViewLocationResults = new ConcurrentDictionary<string, ViewLocationResult>();
foreach (var replace in replacements)
{
_cachedViewLocationResults.AddOrUpdate(replace.Key, x=>replacements[x], (x,y)=>y);
}
}
}
//END OF IViewLocator
//here is what I did in the custom IViewCache
//another static for ViewCache to tell if the view has been updated
public static List<ViewLocationResult> Exceptions { get; private set; }
//...some other code
//here is how I ignore the old cache
public TCompiledView GetOrAdd<TCompiledView>(ViewLocationResult viewLocationResult, Func<ViewLocationResult, TCompiledView> valueFactory)
{
if (Exceptions.Any(x=>x.Name == viewLocationResult.Name && x.Location == viewLocationResult.Location && x.Extension == viewLocationResult.Extension))
{
object old;
this.cache.TryRemove(viewLocationResult, out old);
Exceptions.Remove(viewLocationResult);
}
return (TCompiledView)this.cache.GetOrAdd(viewLocationResult, x => valueFactory(x));
}
With those implentions and a little bit of settings on the bootstrapper plus a router for some mysql update, I can update the View the way I want, but here is the problem:
1. now I have to manually map all the Location,Name,Extension for the ViewLocationResult to use and there are too many of them (243...), I would like to use the some sort of built-in function to identify the changes, something like the IsStale function of the ViewLocationResult, but I didnt know which and how...
2. those static class are ugly and I think it could be problematic but I didnt know a better way to replace them.
Could some one kindly give me a hint, thank in advance.

Well, I finally figure out how to do this myself, just in case anyone else want to use the same method as I do, Here is how you update your view in memory:
Make a interface
public interface INewViewLocationResultProvider
{
bool UseCachedView { get; set; }
ViewLocationResult GetNewerVersion(string viewName, NancyContext context);
void UpdateCachedView(IDictionary<string, ViewLocationResult> replacements);
}
Make a new ViewLocationResultProvider
public class ConcurrentNewViewLocationResultProvider : INewViewLocationResultProvider
{
private Dictionary<string, ViewLocationResult> _cachedViewLocationResults;
private readonly object _cacheLock = new object();
public bool UseCachedView { get; set; }
public ConcurrentNewViewLocationResultProvider()
{
lock (_cacheLock)
{
if(_cachedViewLocationResults == null)_cachedViewLocationResults = new Dictionary<string, ViewLocationResult>();
}
}
public ViewLocationResult GetNewerVersion(string viewName, NancyContext context)
{
if (UseCachedView)
{
if (Monitor.TryEnter(_cacheLock, TimeSpan.FromMilliseconds(20)))
{
try
{
if (_cachedViewLocationResults != null && _cachedViewLocationResults.ContainsKey(viewName))
{
return _cachedViewLocationResults[viewName];
}
}
finally
{
Monitor.Exit(_cacheLock);
}
}
}
return null;
}
public void UpdateCachedView(IDictionary<string, ViewLocationResult> replacements)
{
lock (_cacheLock)
{
if(_cachedViewLocationResults == null)_cachedViewLocationResults = new Dictionary<string, ViewLocationResult>();
foreach (var replace in replacements)
{
if (_cachedViewLocationResults.ContainsKey(replace.Key))
{
_cachedViewLocationResults[replace.Key] = replace.Value;
}
else
{
_cachedViewLocationResults.Add(replace.Key,replace.Value);
}
}
}
}
}
In your Bootstrapper,register the new ViewLocationResultProvider with tinyIoc or equivalent
container.Register<INewViewLocationResultProvider, ConcurrentNewViewLocationResultProvider>().AsSingleton();
Make a derived class from ViewLocationResult
public class OneTimeUsedViewLocationResult : ViewLocationResult
{
private bool _used = false;
public OneTimeUsedViewLocationResult(string location, string name, string extension, Func<TextReader> contents)
: base(location, name, extension, contents)
{
}
public override bool IsStale()
{
if (_used) return false;
_used = true;
return true;
}
}
And a new IViewLocator:
public class CachedViewLocator : IViewLocator
{
private readonly INewViewLocationResultProvider _newVersion;
private readonly DefaultViewLocator _fallbackViewLocator;
public CachedViewLocator(IViewLocationProvider viewLocationProvider, IEnumerable<IViewEngine> viewEngines, INewViewLocationResultProvider newVersion)
{
_fallbackViewLocator = new DefaultViewLocator(viewLocationProvider, viewEngines);
_newVersion = newVersion;
}
public ViewLocationResult LocateView(string viewName, NancyContext context)
{
if (_newVersion.UseCachedView)
{
var result = _newVersion.GetNewerVersion(viewName, context);
if (result != null) return result;
}
return _fallbackViewLocator.LocateView(viewName, context);
}
public IEnumerable<ViewLocationResult> GetAllCurrentlyDiscoveredViews()
{
return _fallbackViewLocator.GetAllCurrentlyDiscoveredViews();
}
}
}
Tell nancy about the new ViewLocator
protected override NancyInternalConfiguration InternalConfiguration
{
get
{
return NancyInternalConfiguration.WithOverrides
(
nic =>
{
nic.ViewLocationProvider = typeof(ResourceViewLocationProvider);//use this or your equivalent
nic.ViewLocator = typeof(CachedViewLocator);
}
);
}
}
Then you can update it through a API like this:
public class YourModule : NancyModule
{
public YourModule(INewViewLocationResultProvider provider)
{
Get["/yourupdateinterface"] = param =>
{
if(!provider.UseCachedView) return HttpStatusCode.BadRequest;//in case you turn off the hot update
//you can serialize your OneTimeUsedViewLocationResult with Newtonsoft.Json and store those views in any database, like mysql, redis, and load them here
//data mock up
TextReader tr = new StringReader(Resources.TextMain);
var vlr = new OneTimeUsedViewLocationResult("","index","cshtml",()=>tr);
var dir = new Dictionary<string, ViewLocationResult> {{"index",vlr}};
//mock up ends
provider.UpdateCachedView(dir);
return HttpStatusCode.OK;
}
}
}
Note: Those code above doesn't solve the manually map all the Location,Name,Extension for the ViewLocationResult thing menthions in my question, but since I endup build a view editor for my colleges to upload their views, I don't need to solve it anymore.

Intercepting method calls in C# using Proxies

What I'm trying to do is to be able to intercept calls to an object's methods and properties for cross-cutting concerns. I'm using proxy-based AOP using ContextBoundObject.
However this doesn't work for recursive method calls, The first call against the target will be intercepted by the proxy and successfully invoked, allowing me to do cross-cut here. However subsequent method calls from within the first method will stay within the target class and are not intercepted by the proxy as if no marshaling occurs!
Is there any way I can make it work? (I'm trying to avoid third-party libraries like PostSharp, Unity or Spring.Net)
class Program
{
static void Main(string[] args)
{
var t = new SimpleObject();
t.TestMethod1();
}
}
[Intercept]
class SimpleObject : ContextBoundObject
{
public string TestMethod1()
{
return TestMethod2();
}
public string TestMethod2()
{
return "test";
}
}
[AttributeUsage(AttributeTargets.Class)]
public class InterceptAttribute : ContextAttribute, IContributeObjectSink
{
public InterceptAttribute()
: base("Intercept")
{ }
public override bool IsContextOK(Context ctx, IConstructionCallMessage ctorMsg)
{
return false;
}
public IMessageSink GetObjectSink(MarshalByRefObject obj, IMessageSink nextSink)
{
return new InterceptSink(nextSink);
}
}
public class InterceptSink : IMessageSink
{
public IMessageSink NextSink { get; private set; }
public InterceptSink(IMessageSink nextSink)
{
this.NextSink = nextSink;
}
public IMessage SyncProcessMessage(IMessage msg)
{
IMethodCallMessage mcm = (msg as IMethodCallMessage);
// { cross-cut here }
IMessage rtnMsg = this.NextSink.SyncProcessMessage(msg);
IMethodReturnMessage mrm = (rtnMsg as IMethodReturnMessage);
// { cross-cut here }
return mrm;
}
public IMessageCtrl AsyncProcessMessage(IMessage msg, IMessageSink replySink)
{
return null;
}
}

C# designers have never been in favor of AOP, there's no easy way to intercept method calls without using Proxies and Marshaling, which have their own drawbacks!
In case anyone wants to intercept method/property calls (eg. cross cutting concerns), I've found RealProxy to be of some help.
RealProxy From MSDN:
A client that uses an object across any kind of a remoting boundary is
actually using a transparent proxy for the object. The transparent
proxy provides the illusion that the actual object resides in the
client's space. It achieves this by forwarding calls made on it to the
real object using the remoting infrastructure.
Note: A type being proxied using RealProxy must be either an interface or inherit from MarshalByRefObject.
Here's some implementation of RealProxy using a Factory Method to create a proxy of an object at runtime:
public abstract class RuntimeProxy
{
public static readonly object Default = new object();
public static Target Create<Target>(Target instance, RuntimeProxyInterceptor interceptor) where Target : class
{
return (Target)new InternalProxy<Target>(instance, interceptor).GetTransparentProxy();
}
public static Target Create<Target>(Target instance, Func<RuntimeProxyInvoker, object> factory) where Target : class
{
return (Target)new InternalProxy<Target>(instance, new InternalRuntimeProxyInterceptor(factory)).GetTransparentProxy();
}
class InternalProxy<Target> : RealProxy where Target : class
{
readonly object Instance;
readonly RuntimeProxyInterceptor Interceptor;
public InternalProxy(Target instance, RuntimeProxyInterceptor interceptor)
: base(typeof(Target))
{
Instance = instance;
Interceptor = interceptor;
}
public override IMessage Invoke(IMessage msg)
{
var methodCall = (IMethodCallMessage)msg;
var method = (MethodInfo)methodCall.MethodBase;
try
{
var result = Interceptor.Invoke(new InternalRuntimeProxyInterceptorInvoker(Instance, method, methodCall.InArgs));
if (result == RuntimeProxy.Default)
result = method.ReturnType.IsPrimitive ? Activator.CreateInstance(method.ReturnType) : null;
return new ReturnMessage(result, null, 0, methodCall.LogicalCallContext, methodCall);
}
catch (Exception ex)
{
if (ex is TargetInvocationException && ex.InnerException != null)
return new ReturnMessage(ex.InnerException, msg as IMethodCallMessage);
return new ReturnMessage(ex, msg as IMethodCallMessage);
}
}
}
class InternalRuntimeProxyInterceptor : RuntimeProxyInterceptor
{
readonly Func<RuntimeProxyInvoker, object> Factory;
public InternalRuntimeProxyInterceptor(Func<RuntimeProxyInvoker, object> factory)
{
this.Factory = factory;
}
public override object Invoke(RuntimeProxyInvoker invoker)
{
return Factory(invoker);
}
}
class InternalRuntimeProxyInterceptorInvoker : RuntimeProxyInvoker
{
public InternalRuntimeProxyInterceptorInvoker(object target, MethodInfo method, object[] args)
: base(target, method, args)
{ }
}
}
public abstract class RuntimeProxyInterceptor
{
public virtual object Invoke(RuntimeProxyInvoker invoker)
{
return invoker.Invoke();
}
}
public abstract class RuntimeProxyInvoker
{
public readonly object Target;
public readonly MethodInfo Method;
public readonly ReadOnlyCollection<object> Arguments;
public RuntimeProxyInvoker(object target, MethodInfo method, object[] args)
{
this.Target = target;
this.Method = method;
this.Arguments = new ReadOnlyCollection<object>(args);
}
public object Invoke()
{
return Invoke(this.Target);
}
public object Invoke(object target)
{
if (target == null)
throw new ArgumentNullException("target");
try
{
return this.Method.Invoke(target, this.Arguments.ToArray());
}
catch (TargetInvocationException ex)
{
throw ex.InnerException;
}
}
}
You can use the RuntimeProxy as a factory to create a proxy of an object and intercept all method/property calls and invoke the actual method.
Here's a sample:
class SomeClass : MarshalByRefObject
{
public int Mul(int a, int b)
{
return a * b;
}
public void SetValue(int val)
{
this.Val = val;
}
public int Val { get; set; }
}
Use RuntimeProxy class to create a proxy for an instance of the SomeClass class and intercept the calls:
var test = new SomeClass();
var proxy = RuntimeProxy.Create(test, t =>
{
// cross-cut here
return t.Invoke(); // invoke the actual call
});
var res = proxy.Mul(3, 4); // method with return value
proxy.SetValue(2); // void method, setting some property
var val = proxy.Val; // property access
You could use interface types in case you don't want to inherit from MarshalByRefObject class.

NSubstitute and Unity

I am currently trying to learn DI & Mocking, with Unity and NSubstitute. I am also using an automocking extension taken from this question: Is this possible with Unity (Instead of Castle Windsor)?
In my unit test below I am trying to set an NSubstitute return value of 10 from my method Add(). However when debugging through the controller call the assigned value is the default 0 rather than the expected 10. The proxy does not seem to be intercepting the method call.
I suspect this is caused by not registering my Types/container correctly, anybody able to point me in the right direction?
[TestFixture]
public class ApplicationControllerTests
{
private IUnityContainer _container;
private ApplicationController _controller;
private ISampleService _sampleService;
[SetUp]
public void SetUp()
{
_container = new UnityContainer().AddExtension(new AutoMockingContainerExtension());
_controller = _container.Resolve<ApplicationController>();
_sampleService = _container.Resolve<ISampleService>();
}
[Test]
public void TestSampleService()
{
// This line is not working
_sampleService.Add(Arg.Any<int>(), Arg.Any<int>()).Returns(10);
var result = _controller.Index();
_sampleService.Received().Add(Arg.Any<int>(), Arg.Any<int>());
}
}
public class AutoMockingContainerExtension : UnityContainerExtension
{
protected override void Initialize()
{
var strategy = new AutoMockingBuilderStrategy(Container);
Context.Strategies.Add(strategy, UnityBuildStage.PreCreation);
}
class AutoMockingBuilderStrategy : BuilderStrategy
{
private readonly IUnityContainer _container;
public AutoMockingBuilderStrategy(IUnityContainer container)
{
_container = container;
}
public override void PreBuildUp(IBuilderContext context)
{
var key = context.OriginalBuildKey;
if (key.Type.IsInterface && !_container.IsRegistered(key.Type))
context.Existing = CreateSubstitute(key.Type);
}
private static object CreateSubstitute(Type type)
{
return Substitute.For(new[] { type }, null);
}
}
}
And my controller code
public class ApplicationController : BaseController
{
private readonly ISampleService _sampleService;
public ApplicationController(ISampleService sampleService)
{
_sampleService = sampleService;
}
public ActionResult Index()
{
var result = _sampleService.Add(2, 3);
// result is 0, expected 10 ??
return View();
}
}
public interface ISampleService
{
int Add(int first, int second);
}
public class SampleService : ISampleService
{
public int Add(int first, int second)
{
return first + second;
}
}

Actually Tormod is right the problem is that the AutoMockingBuilderStrategy returns a different mock instance every time when somebody requests an ISampleService form the container.
So there is a bug in my original implementation namely the AutoMockingBuilderStrategy doesn't store the created mocks:
Here is a fixed version:
public class AutoMockingContainerExtension : UnityContainerExtension
{
protected override void Initialize()
{
var strategy = new AutoMockingBuilderStrategy(Container);
Context.Strategies.Add(strategy, UnityBuildStage.PreCreation);
}
class AutoMockingBuilderStrategy : BuilderStrategy
{
private readonly IUnityContainer container;
private readonly Dictionary<Type, object> substitutes
= new Dictionary<Type, object>();
public AutoMockingBuilderStrategy(IUnityContainer container)
{
this.container = container;
}
public override void PreBuildUp(IBuilderContext context)
{
var key = context.OriginalBuildKey;
if (key.Type.IsInterface && !container.IsRegistered(key.Type))
{
context.Existing = GetOrCreateSubstitute(key.Type);
context.BuildComplete = true;
}
}
private object GetOrCreateSubstitute(Type type)
{
if (substitutes.ContainsKey(type))
return substitutes[type];
var substitute = Substitute.For(new[] {type}, null);
substitutes.Add(type, substitute);
return substitute;
}
}
}

I suspect that you are dealing with two different instances of ISampleService, created in lines 2 and 3 of Setup, respectively.
Could you, for test, make the _sampleServie field public and in the third Setup() line try
_sampleService = _controller._sampleService;

Modify existing WCF communication object

This is how I used to make method calls:
SvcHelper.Using<SomeWebServiceClient>(proxy =>
{
proxy.SomeMethod();
}
public class SvcHelper
{
public static void Using<TClient>(Action<TClient> action) where TClient : ICommunicationObject, IDisposable, new()
{
}
}
This is how I make method calls:
ChannelFactory<ISomethingWebService> cnFactory = new ChannelFactory<ISomethingWebService>("SomethingWebService");
ISomethingWebService client = cnFactory.CreateChannel();
using (new OperationContextScope((IContextChannel)client))
{
client.SomeMethod();
}
My question is: Instead of replacing every instance of my original method call approach; Is there a way to modify my SvcHelper and do the creation of the channel in the SvcHelper constructor and then simply pass the interface like the following:
SvcHelper.Using<ISomethingWebService>(client =>
{
client.SomeMethod();
}
Hope this makes sense and thanks in advance.

First, you don't want to create a new ChannelFactory<T> every call to the Using helper method. They are the most costly thing to construct in the WCF universe. So, at bare minimum, you will want to use a caching approach there.
Second, you don't want to tie yourself to "client" types at all anymore. Just work straight with the service contract interfaces.
Starting from what you've got, here's where I'd go based on how I've done this in the past:
public class SvcHelper
{
private static ConcurrentDictionary<ChannelFactoryCacheKey, ChannelFactory> ChannelFactories = new ConcurrentDictionary<ChannelFactoryCacheKey, ChannelFactory>();
public static void Using<TServiceContract>(Action<TServiceContract> action) where TServiceContract : class
{
SvcHelper.Using<TServiceContract>(action, "*");
}
public static void Using<TServiceContract>(Action<TServiceContract> action, string endpointConfigurationName) where TServiceContract : class
{
ChannelFactoryCacheKey cacheKey = new ChannelFactoryCacheKey(typeof(TServiceContract), endpointConfigurationName);
ChannelFactory<TServiceContract> channelFactory = (ChannelFactory<TServiceContract>)SvcHelper.ChannelFactories.GetOrAdd(
cacheKey,
missingCacheKey => new ChannelFactory<TServiceContract>(missingCacheKey.EndpointConfigurationName));
TServiceContract typedChannel = channelFactory.CreateChannel();
IClientChannel clientChannel = (IClientChannel)typedChannel;
try
{
using(new OperationContextScope((IContextChannel)typedChannel))
{
action(typedChannel);
}
}
finally
{
try
{
clientChannel.Close();
}
catch
{
clientChannel.Abort();
}
}
}
private sealed class ChannelFactoryCacheKey : IEquatable<ChannelFactoryCacheKey>
{
public ChannelFactoryCacheKey(Type channelType, string endpointConfigurationName)
{
this.channelType = channelType;
this.endpointConfigurationName = endpointConfigurationName;
}
private Type channelType;
public Type ChannelType
{
get
{
return this.channelType;
}
}
private string endpointConfigurationName;
public string EndpointConfigurationName
{
get
{
return this.endpointConfigurationName;
}
}
public bool Equals(ChannelFactoryCacheKey compareTo)
{
return object.ReferenceEquals(this, compareTo)
||
(compareTo != null
&&
this.channelType == compareTo.channelType
&&
this.endpointConfigurationName == compareTo.endpointConfigurationName);
}
public override bool Equals(object compareTo)
{
return this.Equals(compareTo as ChannelFactoryCacheKey);
}
public override int GetHashCode()
{
return this.channelType.GetHashCode() ^ this.endpointConfigurationName.GetHashCode();
}
}
}

This should work:
public class SvcHelper
{
public static void Using<TClient>(Action<TClient> action) where TClient : ICommunicationObject, IDisposable
{
ChannelFactory<TClient> cnFactory = new ChannelFactory<TClient>("SomethingWebService");
TClient client = cnFactory.CreateChannel();
using (new OperationContextScope((IContextChannel)client))
{
action(client);
}
}
}

How to improve the Pass an object when navigating to a new view in PRISM 4

I'm using Prism with IoC. The problem is to pass an object (like collections) through navigation. I was watching this post: How to Pass an object when navigating to a new view in PRISM 4
And this is the solution
I extract the hash code of the object and save it in a Dictionary, with the hash code as the key and the object as the value of the pair.
Then, I attach the hash code to the UriQuery.
After, I only have to get the hash code that comes from the Uri on the target view and use it to request the original object from the Dictionary.
Some example code:
Parameter repository class:
public class Parameters
{
private static Dictionary<int, object> paramList =
new Dictionary<int, object>();
public static void save(int hash, object value)
{
if (!paramList.ContainsKey(hash))
paramList.Add(hash, value);
}
public static object request(int hash)
{
return ((KeyValuePair<int, object>)paramList.
Where(x => x.Key == hash).FirstOrDefault()).Value;
}
}
The caller code:
UriQuery q = null;
Customer customer = new Customer();
q = new UriQuery();
Parameters.save(customer.GetHashCode(), customer);
q.Add("hash", customer.GetHashCode().ToString());
Uri viewUri = new Uri("MyView" + q.ToString(), UriKind.Relative);
regionManager.RequestNavigate(region, viewUri);
The target view code:
public partial class MyView : UserControl, INavigationAware
{
// some hidden code
public void OnNavigatedTo(NavigationContext navigationContext)
{
int hash = int.Parse(navigationContext.Parameters["hash"]);
Customer cust = (Customer)Parameters.request(hash);
}
}
That's it.
I'm not sure if this solution is the best to pass objects. I guess this maybe would be a service. Is a good way to do this or is there a better way to do it?

I posted an easier way. Mentioning it here for reference -
I would use the OnNavigatedTo and OnNavigatedFrom methods to pass on the objects using the NavigationContext.
First derive the viewmodel from INavigationAware interface -
public class MyViewModel : INavigationAware
{ ...
You can then implement OnNavigatedFrom and set the object you want to pass as navigation context as follows -
void INavigationAware.OnNavigatedFrom(NavigationContext navigationContext)
{
SharedData data = new SharedData();
...
navigationContext.NavigationService.Region.Context = data;
}
and when you want to receive the data, add the following piece of code in the second view model -
void INavigationAware.OnNavigatedTo(NavigationContext navigationContext)
{
if (navigationContext.NavigationService.Region.Context != null)
{
if (navigationContext.NavigationService.Region.Context is SharedData)
{
SharedData data = (SharedData)navigationContext.NavigationService.Region.Context;
...
}
}
}

I just started using Prism and this is one of the first limitations I ran into. I solved it a different way. I first created a class that inherits from Uri and implements IDictionary (plus some generic methods for easier access)
public class NavigationUri : Uri, IDictionary<Type, object>
{
private IDictionary<Type, object> _internalDictionary = new Dictionary<Type, object>();
public NavigationUri(string uriString) : base(uriString, UriKind.Relative)
{
}
public NavigationUri(string uriString, UriKind uriKind) : base(uriString, uriKind)
{
}
public void Add<T>(T value)
{
Add(typeof(T), value);
}
public void Add(Type key, object value)
{
_internalDictionary.Add(key, value);
}
public bool ContainsKey<T>()
{
return ContainsKey(typeof (T));
}
public bool ContainsKey(Type key)
{
return _internalDictionary.ContainsKey(key);
}
public ICollection<Type> Keys
{
get { return _internalDictionary.Keys; }
}
public bool Remove<T>()
{
return Remove(typeof (T));
}
public bool Remove(Type key)
{
return _internalDictionary.Remove(key);
}
public bool TryGetValue<T>(out object value)
{
return TryGetValue(typeof (T), out value);
}
public bool TryGetValue(Type key, out object value)
{
return _internalDictionary.TryGetValue(key, out value);
}
public ICollection<object> Values
{
get { return _internalDictionary.Values; }
}
public object this[Type key]
{
get { return _internalDictionary[key]; }
set { _internalDictionary[key] = value; }
}
public void Add(KeyValuePair<Type, object> item)
{
_internalDictionary.Add(item);
}
public void Clear()
{
_internalDictionary.Clear();
}
public bool Contains(KeyValuePair<Type, object> item)
{
return _internalDictionary.Contains(item);
}
public void CopyTo(KeyValuePair<Type, object>[] array, int arrayIndex)
{
_internalDictionary.CopyTo(array, arrayIndex);
}
public int Count
{
get { return _internalDictionary.Count; }
}
public bool IsReadOnly
{
get { return _internalDictionary.IsReadOnly; }
}
public bool Remove(KeyValuePair<Type, object> item)
{
return _internalDictionary.Remove(item);
}
public IEnumerator<KeyValuePair<Type, object>> GetEnumerator()
{
return _internalDictionary.GetEnumerator();
}
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return _internalDictionary.GetEnumerator();
}
}
Then I created a class that inherits from RegionNavigationContentLoader. On GetContractFromNavigationContext I store the passed in Uri so I can access it in the CreateNewRegionItem method. In that method I check to see if the Uri is the NavigationUri and if so I loop though adding all the dependency injection overrides. I'm using Unity but I assume the code could easy be converted to another IOC container.
public class BaseRegionNavigationContentLoader : RegionNavigationContentLoader
{
private Uri _uri;
private IServiceLocator _serviceLocator;
private IUnityContainer _unityContainer;
public BaseRegionNavigationContentLoader(IServiceLocator serviceLocator, IUnityContainer unityContainer) : base(serviceLocator)
{
_serviceLocator = serviceLocator;
_unityContainer = unityContainer;
}
protected override string GetContractFromNavigationContext(NavigationContext navigationContext)
{
_uri = navigationContext.Uri;
return base.GetContractFromNavigationContext(navigationContext);
}
protected override object CreateNewRegionItem(string candidateTargetContract)
{
object instance;
try
{
var uri = _uri as NavigationUri;
if (uri == null)
{
instance = _serviceLocator.GetInstance<object>(candidateTargetContract);
}
else
{
// Create injection overrides for all the types in the uri
var depoverride = new DependencyOverrides();
foreach (var supplant in uri)
{
depoverride.Add(supplant.Key, supplant.Value);
}
instance = _unityContainer.Resolve<object>(candidateTargetContract, depoverride);
}
}
catch (ActivationException exception)
{
throw new InvalidOperationException(string.Format(System.Globalization.CultureInfo.CurrentCulture, "CannotCreateNavigationTarget", new object[] { candidateTargetContract }), exception);
}
return instance;
}
}
Now in the prism Bootstrapper you need to register the BaseRegionNavigationContentLoader as IRegionNavigationContentLoader in the ConfigureServiceLocator method. Make sure you mark it as TransientLifetimeManager so it gets newed up each time. The default registration for IRegionNavigationContentLoader is container controlled which makes it act like a singleton but we need a new one each time since we need to pass the uri from one method to the next in a property.
Now I can wright code like the following and still use constructor injection.
var uri = new NavigationUri("MessageBoxView");
uri.Add(messageBoxEventArgs);
regionManager.RequestNavigate(RegionNames.MainRegion, uri);