I've an existing WPF application based on caliburn micro MVVM pattern which was using Ideablade/cocktail for accessing to database. Now I've switched to servicestack and I was keeping on cocktail just for the composition pattern. Since I've noticed it takes quite a bit long to start the application I've done some test and Ninject performs better.
I find extremly usefull the MEF approach of defining the Export/ImportingConstrucor approach but and I was wondering how I can have it with Ninject... is it possible?
In my current implementation I've something as
[Export(typeof(IMyInterface))]
[Export(typeof(MyFirstViewModel))]
public class MyFirstViewModel:IMyInterface
{
[ImportingConstructor]
public MyFirstViewModel(IEventAggregator eventAggregator)รน
{
}
}
I've seend that in ninject I've to define something as
mKernel.Bind<MyFirstViewModel>().To<MyFirstViewModel>();
mKernel.Bind<MyFirstViewModel>().To<MyFirstViewModel>();
Can it be automatic?
Can I also define a funct to resolve when not found?
Thanks
StackTrace :
at Caliburn.Micro.IoC.<.cctor>b__0(Type service, String key) in c:\Users\Rob\Documents \CodePlex\caliburnmicro\src\Caliburn.Micro.Silverlight\IoC.cs:line 13
at Caliburn.Micro.IoC.Get[T](String key) in c:\Users\Rob\Documents\CodePlex\caliburnmicro\src\Caliburn.Micro.Silverlight\IoC.cs:line 32
at myApp.Modules.Core.Framework.ViewModels.myAppScreenBase`1..ctor() in c:\Projects\myApp\branches\myApp-branch-20140526\myApp\Core\Framework\ViewModels\myAppScreenBase.cs:line 44
at myApp.Modules.Core.Framework.ViewModels.myAppSimpleScreen`1..ctor() in c:\Projects\myApp\branches\myApp-branch-20140526\myApp\Core\Framework\ViewModels\myAppSimpleScreen.cs:line 8
at myApp.Modules.AdE.ViewModels.CMATCLIDDelegheViewModel..ctor(IAdERepository repository, IDialogManager dialogManager, ICommonRepository commonRepository) in c:\Projects\myApp\branches\myApp-branch-20140526\myApp\Modules.AdE\ViewModels\CMATCLIDDelegheViewModel.cs:line 56
at DynamicInjector1033b54d439c44dbaa064db1c7e82f18(Object[] )
at Ninject.Activation.Providers.StandardProvider.Create(IContext context)
at Ninject.Activation.Context.ResolveInternal(Object scope)
at Ninject.Activation.Context.Resolve()
at Ninject.KernelBase.<>c__DisplayClass15.<Resolve>b__f(IBinding binding)
at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
at System.Linq.Enumerable.<CastIterator>d__b1`1.MoveNext()
at System.Linq.SystemCore_EnumerableDebugView`1.get_Items()
RepositoryExport :
public class RepositoryBindingGenerator : IBindingGenerator
{
public IEnumerable<IBindingWhenInNamedWithOrOnSyntax<object>> CreateBindings(Type type, IBindingRoot bindingRoot)
{
foreach (var attribute in type.GetCustomAttributes(typeof(RepositoryAttribute), false)
.OfType<RepositoryAttribute>())
{
yield return bindingRoot
.Bind(attribute.ContractType ?? type)
.To(type).InSingletonScope();
}
}
}
but I got this compile error
Error 19 Cannot implicitly convert type 'Ninject.Syntax.IBindingNamedWithOrOnSyntax' to 'Ninject.Syntax.IBindingWhenInNamedWithOrOnSyntax'. An explicit conversion exists (are you missing a cast?)
Depending on the configuration of ninject (by default its enabled) you don't need to bind a type to itself, ninject will resolve it automatically. So mKernel.Bind<MyFirstViewModel>().To<MyFirstViewModel>(); is superfluous. Remark: Creating the binding anyway also works.
However, if you want to bind Bar to IFoo or Foo to IFoo you need to bind it.
With it you can tell ninject to look for all types with an [Export] attribute and bind these.
Here comes the ninject conventions extension to the rescue. Get the ninject.extensions.conventions nuget package.
Then create a convention binding:
kernel.Bind(x => x
.FromThisAssembly()
.SelectAllClasses()
.WithAttribute<ExportAttribute>()
.BindWith<ExportBindingGenerator>());
public class ExportBindingGenerator : IBindingGenerator
{
public IEnumerable<IBindingWhenInNamedWithOrOnSyntax<object>> CreateBindings(Type type, IBindingRoot bindingRoot)
{
foreach (var attribute in type.GetCustomAttributes<ExportAttribute>())
{
yield return bindingRoot
.Bind(attribute.ContractType)
.To(type);
}
}
}
Things get a bit more complicated when you need to also use the [ImportingConstructor] attribute to tell ninject which constructor to use. But i would suppose that you don't need it, since Ninject's auto-constructor-selection. What you can do however is replace all [ImportingConstructor] attributes with Ninject's [Inject] attribute which does exactly the same.
Notes:
You may need to use another method than .FromThisAssembly() to specify all the assemblies which contain the implementation types.
If the implementation types are not public, you need to add IncludeNonePublicTypes() to the convention.
Related
In my submodule, I have:
public class CustomerRepository : ICustomerRepository
{
private readonly IDBEngine _dbEngine;
[CanBeNull] private readonly string _overriddenDebugEmail;
[Obsolete("Use the other constructor")]
public CustomerRepository(IDBEngine dbEngine)
{
_dbEngine = dbEngine;
_overriddenDebugEmail = null;
}
// ReSharper disable once UnusedMember.Global
public CustomerRepository(IDBEngine dbEngine, IDebugConstants debugConstants)
{
_dbEngine = dbEngine;
_overriddenDebugEmail = debugConstants.OverridingDebugEmail;
}
...
The problem is, when I simply update the submodule without implementing IDebugConstants, I get the following runtime error:
Error activating IDebugConstants
No matching bindings are available, and the type is not self-bindable.
I want Ninject to bind to the Obsolete constructor if IDebugConstants is not implemented. But it refuses to because of the obsolete attribute.
In theory I could remove the Obsolete attribute, but I want it to show that that code should no longer exist once all old programs using the submodule have been updated.
Is there some way to make Ninject ignore the Obsolete attribute?
Or am I going about this entirely wrong somehow?
You can do this by adding the [Inject] attribute to your [Obsolete] constructor.
The reason for this is how the constructor scoring is implemented. Specifically this section of the Score method:
if (directive.Constructor.HasAttribute(this.settings.InjectAttribute))
{
return int.MaxValue;
}
if (directive.Constructor.HasAttribute(typeof(ObsoleteAttribute)))
{
return int.MinValue;
}
You will see that if the constructor has the [Obsolete] attribute then it is given the minimum possible score. But prior to that, if the constructor has the [Inject] attribute then it will be given the highest possible score.
This doesn't help in the specific case you mentioned where you want a conditional binding when IDebugConstants is not implemented, but it does answer "Is there some way to make Ninject ignore the Obsolete attribute?"
In summary:
I've undefined of unknowed IProducerPlugin implementations on several assemblies located on a plugins folder.
I've a Core object stores a list of current registered users.
Core is Composition Root.
So, I need:
To create as many IProducerPlugin inherited class objects as the number of registered users.
When a new user is un/registered I need to create / release these objects.
In order to register my "plugins":
this.Kernel.Bind(b => b.FromAssembliesMatching("*")
.SelectAllClasses()
.InheritedFrom(typeof(Extensibility.IProducerPlugin))
.BindAllInterfaces());
I'm not quite figuring out how to implement this.
Could you help me please?
I'll appreciate a LOT your help.
DI containers in general and Ninject in special are not suitable to add and remove new bindings to the container during runtime. Some, like Autofac, don't even allow adding bindings once the container is created.
Ninject allows adding new bindings at any time, but you cannot, ever, remove them (*from some use cases there's Rebind, but that's not the same).
kernel.Release(object) is not removing the binding, it's only removing all references to the object that it holds.
For example:
var foo = new object();
kernel.Bind<object>().ToConstant(foo);
to allow garbage collecting of foo you can do one of the following:
kernel.Release(foo);
kernel.Dispose(); kernel = null;
and exactly this is what kernel.Release(...) is for. Maybe you could also Release a singleton and thus force ninject to create a new one on the next request. But i don't know whether this really works, and if it does, it certainly is quite an unexpected hack.
So what you should do is manage the list/dictionary yourself. You can bind and inject the list/dictionary/manager what ever you call it using ninject, but you cannot have ninject manager the list itself.
I've managed to do something like that similar using this a IBindingGenerator interface method...
I've used .BindWith<>() binding method...
this.Kernel.Bind(b => b.FromAssembliesMatching("*")
.SelectAllClasses()
.InheritedFrom(typeof(Extensibility.IProducerPlugin))
.BindWith<PluginBindingGenerator<Extensibility.IProducerPlugin>>()
);
I've implemented a IBindingGenerator:
public class PluginBindingGenerator<T> : IBindingGenerator
{
public System.Collections.Generic.IEnumerable<Ninject.Syntax.IBindingWhenInNamedWithOrOnSyntax<object>> CreateBindings(Type type, Ninject.Syntax.IBindingRoot bindingRoot)
{
if (type != null && !type.IsAbstract && type.IsClass && typeof(T).IsAssignableFrom(type))
{
Ninject.Syntax.IBindingWhenInNamedWithOrOnSyntax<object> syntax = bindingRoot.Bind(typeof(Extensibility.IProducerPlugin)).ToProvider(new PluginProvider());
yield return (Ninject.Syntax.IBindingWhenInNamedWithOrOnSyntax<object>)syntax;
}
}
}
public class PluginProvider : IProvider<object>
{
private System.Collections.Generic.Dictionary<Domain.Identity.ClientIdentity, Extensibility.IProducerPlugin> plugins;
And then, the provider:
public PluginProvider()
{
this.plugins = new System.Collections.Generic.Dictionary<Domain.Identity.ClientIdentity, Extensibility.IProducerPlugin>();
}
public object Create(IContext ctx)
{
//... I don't know what to do here...
return objects;
}
public Type Type
{
get { throw new NotImplementedException(); }
}
}
I just recently started using Ninject (v2.2.0.0) in my ASP.NET MVC 3 application. So far I'm thrilled with it, but I ran into a situation I can't seem to figure out.
What I'd like to do is bind an interface to concrete implementations and have Ninject be able to inject the concrete implementation into a constructor using a factory (that will also be registered with Ninject). The problem is that I'd like my constructor to reference the concrete type, not the interface.
Here is an example:
public class SomeInterfaceFactory<T> where T: ISomeInterface, new()
{
public T CreateInstance()
{
// Activation and initialization logic here
}
}
public interface ISomeInterface
{
}
public class SomeImplementationA : ISomeInterface
{
public string PropertyA { get; set; }
}
public class SomeImplementationB : ISomeInterface
{
public string PropertyB { get; set; }
}
public class Foo
{
public Foo(SomeImplementationA implA)
{
Console.WriteLine(implA.PropertyA);
}
}
public class Bar
{
public Bar(SomeImplementationB implB)
{
Console.WriteLine(implB.PropertyB);
}
}
Elsewhere, I'd like to bind using just the interface:
kernel.Bind<Foo>().ToSelf();
kernel.Bind<Bar>().ToSelf();
kernel.Bind(typeof(SomeInterfaceFactory<>)).ToSelf();
kernel.Bind<ISomeInterface>().To ...something that will create and use the factory
Then, when requesting an instance of Foo from Ninject, it would see that one of the constructors parameters implements a bound interface, fetch the factory, and instantiate the correct concrete type (SomeImplementationA) and pass it to Foo's constructor.
The reason behind this is that I will have many implementations of ISomeInterface and I'd prefer to avoid having to bind each one individually. Some of these implementations may not be known at compile time.
I tried using:
kernel.Bind<ISomeInterface>().ToProvider<SomeProvider>();
The provider retrieves the factory based on the requested service type then calls its CreateInstance method, returning the concrete type:
public class SomeProvider : Provider<ISomeInterface>
{
protected override ISomeInterface CreateInstance(IContext context)
{
var factory = context.Kernel.Get(typeof(SomeInterfaceFactory<>)
.MakeGenericType(context.Request.Service));
var method = factory.GetType().GetMethod("CreateInstance");
return (ISomeInterface)method.Invoke();
}
}
However, my provider was never invoked.
I'm curious if Ninject can support this situation and, if so, how I might go about solving this problem.
I hope this is enough information to explain my situation. Please let me know if I should elaborate further.
Thank you!
It seems you have misunderstood how ninject works. In case you create Foo it sees that it requires a SomeImplementationA and will try to create an instance for it. So you need to define a binding for SomeImplementationA and not for ISomeInterface.
Also most likely your implementation breaks the Dependency Inversion Princple because you rely upon concrete instances instead of abstractions.
The solution to register all similar types at once (and the prefered way to configure IoC containers) is to use configuration by conventions. See the Ninject.Extensions.Conventions extenstion.
I'm working on a framework extension which handles dynamic injection using Ninject as the IoC container, but I'm having some trouble trying to work out how to achieve this.
The expectation of my framework is that you'll pass in the IModule(s) so it can easily be used in MVC, WebForms, etc. So I have the class structured like this:
public class NinjectFactory : IFactory, IDisposable {
readonly IKernel kernel;
public NinjectFactory(IModule[] modules) {
kernel = new StandardKernel(modules);
}
}
This is fine, I can create an instance in a Unit Test and pass in a basic implementation of IModule (using the build in InlineModule which seems to be recommended for testing).
The problem is that it's not until runtime that I know the type(s) I need to inject, and they are requested through the framework I'm extending, in a method like this:
public IInterface Create(Type neededType) {
}
And here's where I'm stumped, I'm not sure the best way to check->create (if required)->return, I have this so far:
public IInterface Create(Type neededType) {
if(!kernel.Components.Has(neededType)) {
kernel.Components.Connect(neededType, new StandardBindingFactory());
}
}
This adds it to the components collection, but I can't work out if it's created an instance or how I create an instance and pass in arguments for the .ctor.
Am I going about this the right way, or is Ninject not even meant to be be used that way?
Unless you want to alter or extend the internals of Ninject, you don't need to add anything to the Components collection on the kernel. To determine if a binding is available for a type, you can do something like this:
Type neededType = ...;
IKernel kernel = ...;
var registry = kernel.Components.Get<IBindingRegistry>();
if (registry.Has(neededType)) {
// Ninject can activate the type
}
Very very late answer but Microsoft.Practices.Unity allows Late Binding via App.Config
Just in case someone comes across this question
I have a class TxRx with a property called Common. Common then has a property called LastMod. I want to write a RhinoMock expectation to show that LastMod has been set with something. So I tried:
var txRx = MockRepository.GenerateMock<TxRx>();
var common = MockRepository.GenerateMock<Common>();
txRx.Expect(t => t.Common).Return(common);
txRx.Expect(t => t.Common.LastMod).SetPropertyAndIgnoreArgument();
But I get the following exception:
System.InvalidOperationException: Invalid call, the last call has been used or no call has been made (make sure that you are calling a virtual (C#) / Overridable (VB) method).
at Rhino.Mocks.LastCall.GetOptions[T]()
at Rhino.Mocks.RhinoMocksExtensions.Expect[T,R](T mock, Function`2 action)
at ...
I presume this means Common needs to be virtual, but as it is a property on a LinqToSql generated class I can't make it virtual (other than hacking the autogen code which is not really an option).
Is there any way around this?
One possibility is to wrap TxRx in a mockable class (i.e. one that has overridable methods and properties which you wish to mock out or implements an interface which defines the properties or methods that you're interested in) and then pass around the wrapper rather than the LinqToSQL class itself.
Perhaps something like the following:
public class TxRxWrapper : ITxRxWrapper
{
private TxRx m_txrx;
public object LastMod
{
get { return m_txrx.Common.LastMod; }
}
...
}
public interface ITxRxWrapper
{
public object LastMod { get; }
...
}
Not ideal (i.e. it can get somewhat cumbersome to pass wrappers around just for mockability!) but that's the only way you can get RhinoMocks to mock properties/methods for you.
The other option is to use TypeMock instead which I believe uses a different mechanism to mock stuff out. I don't think it's free, though.
You would need to replace your second expectation with
txRx.Expect(() => common.LastMod).SetPropertyAndIgnoreArgument();
But the Common property itself needs to be virtual for this to work.