如何在autofac中传递解析时间参数

问题描述

我在autofac中编写以下寄存器类型:

I write following register type in autofac:

 builder.RegisterType<NoteBookContext>()
        .As<DbContext>()
        .WithParameter(ResolvedParameter.ForNamed<DbContext>("connectionstring"));

实际上，我编写了这段代码，用于使用connectionstring参数注入NoteBookContext. (即:new NoteBookContext(string connectionstring))

In fact I write this code for injecting NoteBookContext with a connectionstring parameter. (ie : new NoteBookContext(string connectionstring))

现在，如何在运行时传递参数值?

Now , How can I Pass value of parameter at runtime?

推荐答案

WithParameter方法具有一个重载，可以接受委托进行动态实例化.

The WithParameter method has a overload that accept delegate for dynamic instanciation.

第一个参数是谓词，选择要设置的参数，而第二个参数是参数值提供者:

The first argument is a predicate selecting the parameter to set whereas the second is the argument value provider :

builder.RegisterType<NoteBookContext>()
       .As<DbContext>()
       .WithParameter((pi, c) => pi.Name == "connectionstring",
                      (pi, c) => c.Resolve<IConnectionStringProvider>().ConnectionString);

请参见将参数从 Autofac传递到注册 em>文档以获取更多详细信息.

See Passing Parameters to Register from Autofac documentation for more detail.

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