Ninject Binding Constraint that searches up to find a type

Question

I've got a class hierarchy like this (simplified):

class Connection
{
}

interface IService<T>
{
}


class ServiceImplementation : IService<int>
{
   public ServiceImplementation(Connection)
   {
   }
}

interface IConnectionConfiguration
{
   public void Configure(Connection c)
}

class ConnectionConfiguration : IConnectionConfiguration
{
   public void Configure(Connection c)
}

Where I have multiple implementations of IConnectionConfiguration and IService. I am wanting to create a provider/bindings which:

constructs a new instance of Connection.
GetAll and applies that to the Connection.
Bindings specify which IConnectionConfiguration implementations to be used, based on on the type of IService to be constructed

Currently I have a provider implementation like this:

public Connection CreateInstance(IContext context)
{
     var configurations = context.Kernel.GetAll<IConnectionConfiguration>()
     var connection = new Connection();
     foreach(var config in configurations)
     {
        config.Configure(connection);
     }

     return connection;
}

But when I try to make the contextual binding for IConnectionConfiguration it doesn't have a parent request or parent context...

Bind<IConnectionConfiguration>().To<ConcreteConfiguration>().When(ctx => {
 // loop through parent contexts and see if the Service == typeof(IService<int>);
 // EXCEPT: The ParentRequest and ParentContext properties are null.
});

What am I doing wrong here? Can I do this with ninject?

score 2 · Accepted Answer · edited Oct 04 '11 at 20:08

2

By calling kernel.GetAll you are creating a new request. It has no information about the service context. There is an extension that allows you to create new requests that preserve the original context (Ninject.Extensions.ContextPreservation)

See also https://github.com/ninject/ninject.extensions.contextpreservation/wiki

context.GetContextPreservingResolutionRoot().GetAll<IConnectionConfiguration>();

edited Oct 04 '11 at 20:08

Ruben Bartelink

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answered Oct 02 '11 at 21:25

Remo Gloor

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thanks, I would prefer not to have to add an extension to the project, is there a way I can "manually" create a child request preserving the context? – icedtoast Oct 02 '11 at 22:27
1

Why don't you want to add an extension? They are part of the Ninject project. And sure there is a way to do it manually. Do exactly what is done in the extension. But this way you will have to maintain your code yourself. – Remo Gloor Oct 03 '11 at 00:46

Ninject Binding Constraint that searches up to find a type

1 Answers1