Dependency injection for ASP.NET Web API action method parameters

Question

I am working on an ASP.NET Web API project in C# for a JSON interface to a mobile application. My idea was to create interfaces for all requests and then only use these interfac

Answer 1

This is what I came up with now and it works.

I decided to create a custom formatter which does the unity calls and forwards all further operations to another formatter using the resolved type. It looks like a lot of code, but that is only because all the methods need to be overwritten so the type can always be resolved.

public class UnityFormatter : MediaTypeFormatter
{
    private MediaTypeFormatter formatter;

    private IUnityContainer container;

    public UnityFormatter(MediaTypeFormatter formatter, IUnityContainer container)
    {
        this.formatter = formatter;
        this.container = container;

        foreach (var supportedMediaType in this.formatter.SupportedMediaTypes)
        {
            this.SupportedMediaTypes.Add(supportedMediaType);
        }

        foreach (var supportedEncoding in this.formatter.SupportedEncodings)
        {
            this.SupportedEncodings.Add(supportedEncoding);
        }

        foreach (var mediaTypeMapping in this.MediaTypeMappings)
        {
            this.MediaTypeMappings.Add(mediaTypeMapping);
        }

        this.RequiredMemberSelector = this.formatter.RequiredMemberSelector;
    }

    private Type ResolveType(Type type)
    {
        return this.container.Registrations.Where(n => n.RegisteredType == type).Select(n => n.MappedToType).FirstOrDefault() ?? type;
    }

    public override bool CanReadType(Type type)
    {
        return this.formatter.CanReadType(this.ResolveType(type));
    }

    public override bool CanWriteType(Type type)
    {
        return this.formatter.CanWriteType(this.ResolveType(type));
    }

    public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type, HttpRequestMessage request, MediaTypeHeaderValue mediaType)
    {
        return this.formatter.GetPerRequestFormatterInstance(this.ResolveType(type), request, mediaType);
    }

    public override Task