Windsor Container: How to specify a public property should not be filled by the container?

Question

When Instantiating a class, Windsor by default treats all public properties of the class as optional dependencies and tries to satisfy them. In my case, this creates a rather complicated circular dependency which causes my application to hang.

How can I explicitly tell Castle Windsor that it should not be trying to satisfy a public property? I assume there must be an attribute to that extent. I can't find it however so please let me know the appropriate namespace/assembly.

If there is any way to do this without attributes (such as Xml Configuration or configuration via code) that would be preferable since the specific library where this is happening has to date not needed a dependency on castle.

Maturate

Added this question to the Windsor FAQ: using.castleproject.org/display/IoC/FAQ – Contradistinguish

Answer 1

I created a facility to help with this:

• Castle.Facilities.OptionalPropertyInjection

Maturate

@GorgiRankovski I'm not sure that this package is relevant for modern versions of Castle.Windsor (I use Structuremap or Autofaq nowadays so I don't know). You can get the source code from this old svn on google code – Maturate

Answer 2

You can use the Castle.Core.DoNotWireAttribute attribute to stop a property from being wired up by the IoC container (this is in the Castle.Core assembly, which means your library only needs to take a dependency on the lightweight Castle.Core assembly - if for example you want to use the code without an inversion of control container altogether, or in a different IoC container).

I don't believe there's any way to prevent wiring from occurring in the Xml configuration, but it would be reasonably easy to add support for this - if I had to do this I would probably:

1. Introduce some kind of attribute on the property declaration in the xml: <myprop wire="false" />
2. Inherit from PropertiesDependenciesModelInspector, overriding the InspectProperties method to apply some additional logic to identifying which properties should be added as dependencies to the components model (inspecting the model.Configuration for the wire="false" attribute/value pair).
3. Inherit from DefaultComponentModelBuilder and override the InitializeContributors to include your replacement PropertiesDependenciesModelInspector - or just remove the existing properties contributor and add your own at run time via the AddContributor/RemoveContributor methods.
4. Replace the ComponentModelBuilder service instance assigned to the kernel of your container.

Another approach which could work for you is to just manually remove the dependencies from the model before any instances of the service are requested ie.

kernel.GetHandler(typeof(MyComponent)).ComponentModel.Dependencies.RemoveAll(d => d.DependencyKey == "PropertyThatShouldNotBeWired");

YMMV with that approach though - especially if you have startable services or other facilities which may be eagerly instantiating your component after it's registered.

Interjection

That code sample doesn't work in 2.5.x - the RemoveAll() method has gone away. Is there an alternative? – Outrage

P.S. I'm using the fluent registration API. – Outrage

Answer 3

I do not know which version of Castle you guys were using at that time, but none of the solution mentioned were working. Plus, there is a lot of dead links.

With castle 3.1, here the solution I came up with (thanks to some castle source code digging):

container.Register(Component.For(type)
                                        .LifestyleTransient()
                                        .Properties( propertyInfo => propertyInfo.PropertyType != typeof(MyOtherType)));

The 'Properties' function adds a property filter used by castle when constructing the ComponentModel. In my case, all properties dependency will be satisfied except the property type 'MyOtherType'.

Bryon

Answer 4

Maybe it will be helpful for someone. In Windsor 4.1 there is PropertiesIgnore method during registration.

Component.For<Role>().LifestyleTransient().PropertiesIgnore((model, propertyInfo) => true)

Retrogressive

Answer 5

DoNotWireAttribute

• Class: http://svn.castleproject.org:8080/svn/castle/trunk/Core/Castle.Core/Attributes/DoNotWireAttribute.cs
• Test: http://svn.castleproject.org:8080/svn/castle/trunk/InversionOfControl/Castle.Windsor.Tests/IgnoreWireTestCase.cs

Donall

Answer 6

This can be achieved by the following code:

var container = new WindsorContainer();

// We don't want to inject properties, only ctors
var propInjector = container.Kernel.ComponentModelBuilder
                         .Contributors
                         .OfType<PropertiesDependenciesModelInspector>()
                         .Single();
container.Kernel.ComponentModelBuilder.RemoveContributor(propInjector);

Source Castle Windsor Documentation

Petty

Answer 7

Posted this on the google groups forum too here: http://groups.google.com/group/castle-project-devel/browse_thread/thread/43aa513817bd057a

Maturate