I have two objects that support the same interface. Each object has its own configuration object that gets passed as a constructor argument. I want Ninject to use the name of the object to resolve the same of its configuration parameter. Currently, if I do kernel.Get("one") it fails to resolve ThingConfig, even though there is exactly one registered by that name. (EDIT: Fixed example to include ThingConfig binding):
class MyService
{
public MyService([Named("one")] IThing one, [Named("two")] IThing two) {}
}
class ThingConfig {}
class Thing(ThingConfig cfg) : IThing {}
And in my binder:
Bind<IThing>().To(typeof(Thing)).InSingletonScope().Named("one");
Bind<IThing>().To(typeof(Thing)).InSingletonScope().Named("two");
Bind<ThingConfig>().ToMethod(() => new ThingConfig()).InSingletonScope().Named("one");
Bind<ThingConfig>().ToMethod(() => new ThingConfig()).InSingletonScope().Named("two");
I think I found an acceptable solution involving Named and WhenAnyAncestorNamed.
I wanted to essentially have a "tag" that identified the scope, so the name fits the bill. I wanted to be able to resolve object by name, or when injected into objects activated by that name. To do that, I had to bind the object twice - once by name, and once for any ancestor with that name:
Bind(interfaces.ToArray()).To(objectType).InSingletonScope().Named(name);
Bind(interfaces.ToArray()).ToMethod(
ctx => ctx.Kernel.Get(ctx.Request.Service, name)).WhenAnyAncestorNamed(name);
If anyone knows a more elegant solution, I'm all ears.
Related
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.
To best describe what I want to happen, i'll show what i'm doing, as to me it makes sense that this would work ...
public class foo()
{
public foo()
{
MyContext db = new MyContext();
foobar = db.foobar.first();
this = Mapper.Map<bar, foo>(foobar);
}
}
Basically, I want to use automapper within the destination class to map from the source class within the destination classes constructor.
Is there a way to do this?
You cannot do this because this is read only in C#. You cannot assign this a value in the constructor. Not cool to try to change the reference of an object in its constructor. You will have to do the mapping manually and assign each individual property. I would also question if it as a good practice to assign an object values from a database or service in a default constructor. It is not very transparent to the user of the object what is going on and you can get an exception in your constructor.
I have looked at the Dozer's FAQs and docs, including the SourceForge forum, but I didn't see any good tutorial or even a simple example on how to implement a custom BeanFactory.
Everyone says, "Just implement a BeanFactory". How exactly do you implement it?
I've Googled and all I see are just jars and sources of jars.
Here is one of my BeanFactories, I hope it helps to explain the common pattern:
public class LineBeanFactory implements BeanFactory {
#Override
public Object createBean(final Object source, final Class<?> sourceClass, final String targetBeanId) {
final LineDto dto = (LineDto) source;
return new Line(dto.getCode(), dto.getElectrified(), dto.getName());
}
}
And the corresponding XML mapping:
<mapping>
<class-a bean-factory="com.floyd.nav.web.ws.mapping.dozer.LineBeanFactory">com.floyd.nav.core.model.Line</class-a>
<class-b>com.floyd.nav.web.contract.dto.LineDto</class-b>
</mapping>
This way I declare that when a new instance of Line is needed then it should create it with my BeanFactory. Here is a unit test, that can explain it:
#Test
public void Line_is_created_with_three_arg_constructor_from_LineDto() {
final LineDto dto = createTransientLineDto();
final Line line = (Line) this.lineBeanFactory.createBean(dto, LineDto.class, null);
assertEquals(dto.getCode(), line.getCode());
assertEquals(dto.getElectrified(), line.isElectrified());
assertEquals(dto.getName(), line.getName());
}
So Object source is the source bean that is mapped, Class sourceClass is the class of the source bean (I'm ignoring it, 'cause it will always be a LineDto instance). String targetBeanId is the ID of the destination bean (too ignored).
A custom bean factory is a class that has a method that creates a bean. There are two "flavours"
a) static create method
SomeBean x = SomeBeanFactory.createSomeBean();
b) instance create method
SomeBeanFactory sbf = new SomeBeanFactory();
SomeBean x = sbf.createSomeBean();
You would create a bean factory if creating and setting up your bean requires some tricky logic, like for example initial value of certain properties depend on external configuration file. A bean factory class allows you to centralize "knowledge" about how to create such a tricky bean. Other classes just call create method without worying how to correctly create such bean.
Here is an actual implementation. Obviously it does not make a lot of sense, since Dozer would do the same without the BeanFactory, but instead of just returning an object, you could initialized it somehow differently.
public class ComponentBeanFactory implements BeanFactory {
#Override
public Object createBean(Object source, Class<?> sourceClass,
String targetBeanId) {
return new ComponentDto();
}
}
Why do you need a BeanFactory anyways? Maybe that would help understanding your question.
I have these classes:
[DataContract]
public class ErrorBase {}
[DataContract]
public class FileMissingError: ErrorBase {}
[DataContract]
public class ResponseFileInquiry
{
[DataMember]
public List<ErrorBase> errors {get;set;};
}
An instance of the class ResponseFileInquiry is what my service method returns to the client. Now, if I fill ResponseFileInquiry.errors with instances of ErrorBase, everything works fine, but if I add an instance of inherited type FileMissingError, I get a service side exception during serialization:
Type 'MyNamespace.FileMissingError' with data contract name 'FileMissingError'
is not expected. Add any types not known statically to the list of known types -
for example, by using the KnownTypeAttribute attribute or by adding them to the
list of known types passed to DataContractSerializer.'
So serializer is getting confused because it's expecting the List to contain the declared type objects (ErrorBase) but it's getting inherited type (FileMissingError) objects.
I have the whole bunch of error types and the List will contain combinations of them, so what can I do to make it work?
You should add KnownType attribute to your base class
[DataContract]
[KnownType(typeof(FileMissingError))]
public class ErrorBase {}
Read more about KnownType attribute in this blog
Try this:
[DataContract]
[KnownType(typeof(FileMissingError))]
public class ErrorBase {}
As the error message states, any information that cannot be know statically (like the polymorphic relationship you have expressed here) must be supplied via attributes. In this case you need to specify that your FileMissingError data contract is a known type of its base class, ErrorBase.
A tad bit late, but maybe for future generations. =)
If you don't want to add an attribute for every child class to your parent class, you could construct a list of known types in the parent classes static constructor using
IEnumerable<Assembly> assemblies = AppDomain.CurrentDomain
.GetAssemblies()
.Where(a => !a.GlobalAssemblyCache);
IEnumerable<Type> serializableTypes = assemblies.SelectMany(a => a.GetTypes())
.Where(t => IsSerializable(t));
// ...
private static bool IsSerializable(Type type)
{
return type.GetCustomAttributes(true).Any(a => a is DataContractAttribute);
}
and pass this list to the de/serializers constructor. I don't know how robust this solution is, but that's what I am doing and so far it works. It is a little slow, so make sure to cache the result.
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.