Replace InjectionFactory with explicit method on IUnityContainer

[ENikS]

Description

Currently to provide factory for the type you have to create InjectionFactory and pass it to the RegisterType method.

Problem

This method has inherent inefficiencies built into it. It requires allocating instance of InjectionFactory , during registration. It also allocates resolution policy to wrap it and provide 'glue' to be called by the Container.

Another issue it does not participate in sharing Per-Resolve dependencies during resolution process.

Solution

Create new method called RegisterFactory to allow registration of the factory delegate.

[karelkral]

Please document how to use replacement methods for InjectionFactory. I am using InjectionFactory in many places.

[ENikS]

I thought it is self explanatory. Instead of calling RegisterType with InjectionFactory as parameter, you pass your factory delegate to RegisterFactory method.

Would you like to contribute proper help wiki?

[kajbonfils]

Yes, please provide a help wiki with an example on how to use it.

[ENikS]

It will be some time... I am working on the documentation project

[hypercodeplace]

Hi @ENikS,
It will be good to be able to pass resolver overrides to the factory too. I have a real production scenario to use it. Am I right it's not possible to pass it for now?

[ENikS]

Could you create a unit test with the scenario so I can look at it?

[jwar-gilson]

Please document how to use replacement methods for InjectionFactory. I am using InjectionFactory in many places.

I am in the same boat

[jwar-gilson]

So I have three examples of our usage and I am not quite sure on how to replace them with container.RegisterFactory. I am new to Unity and I am just trying to update our solution to the latest. Any help would be greatly appreciated :)

Updating from and to:
Unity 5.8.11 => 5.9.7
Unity.Abstractions 3.3.1.0 => 4.1.0.0
Unity.AspNet.WebApi 5.0.15 => 5.9.2
Unity.Container 5.8.11.0 => 5.9.7.0

Added:
Unity.Configuration 5.9.2

Sample 1:

container.RegisterType<ISettingsProvider>(
    new InjectionFactory(x => new BasicSettingsProvider(ConfigurationManager.AppSettings)));

Sample 2:

container.RegisterType<SiteDataContext>(
    new InjectionFactory(unityContainer =>
    {
        var context = OwinRequestScopeContext.Current;
        if (context != null && context.Items.ContainsKey(TenantDataContextKey))
            return (SiteDataContext)context.Items[TenantDataContextKey];

        var appTenant = SampleContext.Current.GetOwinContext().GetTenantContext<AppTenant>().AppTenant;
        var connectionString = ConnectionStringBuilder
            .GetSiteConnectionString(TenantHelper.CatalogName(appTenant.Tenant), TenantHelper.LoginName(appTenant.Tenant));

        var dataContext = new SiteDataContext(connectionString);

        if (context != null)
            context.Items[TenantDataContextKey] = dataContext;

        return dataContext;
    }));

Sample 3:

container
    .RegisterType<MapperConfiguration>(
        new ContainerControlledLifetimeManager(),
        new InjectionFactory(c =>
            new MapperConfiguration(configuration =>
            {
                configuration.ConstructServicesUsing(t => container.Resolve(t));
                foreach (var profile in container.FindAndResolveAllImplementationsOf<Profile>())
                    configuration.AddProfile(profile);
            })))
    .RegisterType<IConfigurationProvider>(
        new ContainerControlledLifetimeManager(),
        new InjectionFactory(c => c.Resolve<MapperConfiguration>()))
    .RegisterType<IMapper>(
        new InjectionFactory(c => c.Resolve<MapperConfiguration>().CreateMapper()));

[ENikS]

All you need to do is to call RegisterFactory and pass a delegate. No need to create a wrapper.

Unity v4 and v5 were not designed not support resolver overrides in factory methods. But since you supply the delegate, you could have a closure with whatever data you want.

SomeObject.SomeDataProperty = data;

container.RegisterFactory<ISettingsProvider>((container, type, name)=>
   new BasicSettingsProvider(SomeObject.SomeDataProperty, ConfigurationManager.AppSettings));

SomeObject.SomeDataProperty could be updated at any time and etc.