如何使用kernel.Get使用ninject创建对象以获取具有特定属性的绑定？

Question

For a test I'm writing I would like to create an object with ninject that is classified with an attribute. Eg, can I make this test pass?

using Ninject;
using NUnit.Framework;
using System;

namespace TestProject
{
    public class RedAttribute : Attribute { }
    public class BlueAttribute : Attribute { }

    public class TestClass
    {
        public string Str;

        public TestClass([Blue] String str)
        {
            Str = str;
        }
    }
    [TestFixture]
    public class SimpleTest
    {

        [Test]
        public void TestFunction()
        {
            IKernel kernel = new StandardKernel();

            kernel.Bind<string>()
                .ToMethod(context => "Red String")
                .WhenTargetHas<RedAttribute>();

            kernel.Bind<string>()
                .ToMethod(context => "Blue String")
                .WhenTargetHas<BlueAttribute>();
            kernel.Bind<TestClass>().ToSelf();

            // this works fine
            TestClass testC = kernel.Get<TestClass>();
            Assert.That(testC.Str, Is.EqualTo("Blue String"));

            // but I can't get the below to work
            // Ideally I would like something statically typed, eg
            // string str = kernel.Get<string, BlueAttribute>();
            string str = "TODO ?????";
            Assert.That(str, Is.EqualTo("Blue String"));

        }
    }
}

Answer 1

The code kernel.Get<string, BlueAttribute>(); will get quite complicated. You can do something like

var request = new Request(
    null,
    typeof (string),
    new ParameterTarget(
        "get method/constructor by reflection",
        "get parameter info of parameter with [Blue attribute]"),
    x => (object)null);
string str = kernel.Resolve(request).OfType<string>().Single();

You might also create a dynamic type instead of writing one and using reflection to get the constructor / parameter info. Or you could use IL emitting to create one.

But i think creating a fake class is way simpler. Actually you don't need the kernel.Bind<TestClass>().ToSelf(); , since it's an instantiatable class, ninject can resolve it without there being a binding.