Autofac:解析对命名实例的特定依赖关系

Question

使用Autofac,我想注册一个组件并指定要解析为命名实例的特定依赖项.

我使用构造函数注入找到了类似下面的示例,这几乎是我想要的.

builder.Register(c => new ObjectContainer(ConnectionStrings.CustomerDB))
    .As<IObjectContainer>()
    .Named("CustomerObjectContainer");

builder.Register(c => new ObjectContainer(ConnectionStrings.FooDB))
    .As<IObjectContainer>()
    .Named("FooObjectContainer");

builder.Register(c => new CustomerRepository(
    c.Resolve<IObjectContainer>("CustomerObjectContainer"));

builder.Register(c => new FooRepository(
    c.Resolve<IObjectContainer>("FooObjectContainer"));

但是,我需要使用属性注入,我不想指定所有依赖项.

就像是:

builder.Register<CustomerRepository>().With<IObjectContainer>("CustomerObjectContainer");    
builder.Register<FooRepository>().With<IObjectContainer>("FooObjectContainer");

所有未指定的依赖项的构建应该在未命名的实例中发生.

谢谢,亚历克斯

[丹尼尔克回答]

对于该类型的任何属性,按类型解析的重载.

    public static IRegistrationBuilder<TLimit, TReflectionActivatorData, TStyle> WithDependency<TLimit, TReflectionActivatorData, TStyle, TProperty>(
        this IRegistrationBuilder<TLimit, TReflectionActivatorData, TStyle> registration,
        Func<IComponentContext, TProperty> valueProvider)
        where TReflectionActivatorData : ReflectionActivatorData
    {
        return registration.WithProperty(new ResolvedParameter((p, c) =>
            {
                PropertyInfo prop;
                return p.TryGetDeclaringProperty(out prop) &&
                    prop.PropertyType == typeof(TProperty);
            },
            (p, c) => valueProvider(c)));
    }

Answer 1

我不认为autofac有一种速记方式可以做到这一点,但可以通过一点点努力.

我写了一个扩展方法来做到这一点.把它扔进静态扩展类,你应该没问题.该扩展还展示了如何做到这一点.

public static IRegistrationBuilder<TLimit, TReflectionActivatorData, TStyle> WithResolvedProperty<TLimit, TReflectionActivatorData, TStyle, TProperty>(
    this IRegistrationBuilder<TLimit, TReflectionActivatorData, TStyle> registration,
    string propertyName, Func<IComponentContext, TProperty> valueProvider)
        where TReflectionActivatorData : ReflectionActivatorData
{
    return registration.WithProperty(new ResolvedParameter((p, c) =>
                                                               {
                                                                   PropertyInfo prop;
                                                                   return p.TryGetDeclaringProperty(out prop) &&
                                                                          prop.Name == propertyName;
                                                               },
                                                           (p, c) => valueProvider(c)));
}

不介意超长方法签名,autofac注册非常冗长.

您可以像这样使用扩展名.

builder.RegisterType<Foo>()
    .WithResolvedProperty("Bar", c => c.Resolve<IBar>());