Ninject 2.0: Property Injection without attribute

Question

Is there a way to use Property Injection in Ninject 2 without using the [Inject] attribute? This creates a dependency to Ninject in the class that will be wired using it and I prefer to avoid having unneeded dependencies to my IoC container, that's why I end up using Constructor Injection more often.

I guess the same applies to Method Injection

Answer 1

You can pass in another [attribute] type to the Kernel upon creation which can be used instead of InjectAttribute, but you'll still have to reference something centrally either way.

There was a similar question very recently about doing PI without attributes - there's no OOTB way to put in a custom scanner but the extensibility points are in there.

In general, constructor injection is good for lots of reasons anyway, including this one.

Answer 2

I followed Ruben's tip and posted a small blog post on how to achieve this

Answer 3

I was able to accomplish this using a Heuristic class:

public sealed class MyInjectionHeuristic : NinjectComponent, IInjectionHeuristic
{
        private static readonly IList<Type> 
            _propertyInjectible = 
                new List<Type>
                {
             typeof(IMyService),
                };

                    /// <summary>
      /// Returns a value indicating whether the specified member should be injected.
      /// </summary>
      /// <param name="member">The member in question.</param>
      /// <returns><c>True</c> if the member should be injected; otherwise <c>false</c>.</returns>
      public bool ShouldInject(MemberInfo member)
      {
       var info = member as PropertyInfo;

       if( member == null || info == null )
        return false;

       if (info.CanWrite)
        return _propertyInjectible.Contains(info.PropertyType);

       if( this.Settings == null )
        return false;

       var propList = member.GetCustomAttributes(this.Settings.InjectAttribute, true);

       return propList.Length > 0;
      }
}

When creating your kernel:

var heuristics = _kernel.Components.Get<ISelector>().InjectionHeuristics;
   heuristics.Add(new MyInjectionHeuristic());

Simple add additional types to the IList when you want to inject other types via properties.