BuildUp method in unity doesn't consider MappingName - unity-container

Question

I have a strange problem with unity BuildUp method. I have one interface that's mapped to three classes. I have given a name to each mapping.
Now I need to inject the dependency in an existing object (it's an attribute so I don't have control over lifetime). I call the BuildUp method to inject the dependency, but it always throws an exception which says that the interface is not mapped.
If I map the interface to one type only and I remove the mappingname, the BuildUp method works.
If I map the interface to one type only and I specify the mappingname, the BuildUp method fail.
I have tried registering types in configuration and code and nothing changes.
I suspect this is a bug, but I would like to know if anyone else has another idea.
This is how i call buildup method:
var newAttr = _container.BuildUp(myAttribute.GetType(), myAttribute, "Mapping1");

Answer 1

I tried to follow your scenario and this sample works
var container = new UnityContainer();
container.RegisterType<IFoo, One>("1", new InjectionProperty("Bar", "1"));
container.RegisterType<IFoo, Two>("2", new InjectionProperty("Bar", "2"));
container.RegisterType<IFoo, Three>("3", new InjectionProperty("Bar", "3"));
One one = new One();
container.BuildUp(one.GetType(), one, "1");
Assert.AreEqual("1", one.Bar);
public interface IFoo
{
string Bar { get; set; }
}
public class One : IFoo
{
public string Bar { get; set; }
}
public class Two : IFoo
{
public string Bar { get; set; }
}
public class Three : IFoo
{
public string Bar { get; set; }
}
Update
var container = new UnityContainer();
container.RegisterType<Person>(new InjectionProperty("Foo"));
container.RegisterType<IFoo, One>("1");
container.RegisterType<IFoo, Two>("2");
container.RegisterType<IFoo, Three>("3");
Person person = container.Resolve<Person>("1");
Assert.IsNotNull(person.Foo);
Assert.IsInstanceOfType(person.Foo, typeof(One));
public class Person
{
public IFoo Foo { get; set; }
}
I guess this is what you mean? Short answer: That's not the way Unity works.
Long answer: You will have to specify a ResolverOverride that does that for you. But even that is not enough as you want the container to create the value you want to inject for you. So you would need to specify a ResolvedParameter as the value for your ResolverOverride. With Unity's out-of-the-box parts the Resolve would look like this
Person person = container.Resolve<Person>(new PropertyOverride("Foo", new ResolvedParameter(typeof(IFoo), "1")));
Or you can use this custom override instead
public class NamedPropertyOverride : ResolverOverride
{
private readonly string propertyName;
private readonly string registrationName;
public NamedPropertyOverride(string propertyName, string registrationName)
{
this.propertyName = propertyName;
this.registrationName = registrationName;
}
public override IDependencyResolverPolicy GetResolver(IBuilderContext context, Type dependencyType)
{
var currentOperation = context.CurrentOperation as ResolvingPropertyValueOperation;
if (currentOperation != null &&
currentOperation.PropertyName == this.propertyName)
{
Type propertyType = currentOperation
.TypeBeingConstructed
.GetProperty(currentOperation.PropertyName, BindingFlags.Instance | BindingFlags.Public)
.PropertyType;
return new NamedTypeDependencyResolverPolicy(propertyType, this.registrationName);
}
return null;
}
}
Change the line that contains the call to Resolve in the above sample to this one
Person person = container.Resolve<Person>(new NamedPropertyOverride("Foo", "1"));
That should do the trick.