rest – 基于权限从WebApi端点进行上下文序列化

Lifecycle of an ASP.NET Web API Message

Delegating Handler

Delegating handlers are an extensibility point in the message pipeline allowing you to massage the Request before passing it on to the rest of the pipeline. The response message on its way back has to pass through the Delegating Handler as well,so any response can also be monitored/filtered/updated at this extensibility point.

Delegating Handlers if required,can bypass the rest of the pipeline too and send back and Http Response themselves.

例

以下是DelegatingHandler的示例实现,它可以操作响应对象或完全替换它.

public class ResponseDataFilterHandler : DelegatingHandler
{
    protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,CancellationToken cancellationToken)
    {
        return base.SendAsync(request,cancellationToken)
            .ContinueWith(task =>
            {
                var response = task.Result;

                //Manipulate content here
                var content = response.Content as ObjectContent;
                if (content != null && content.Value != null)
                {
                    ((SomeObject)content.Value).SomeProperty = null;
                }

                //Or replace the content
                response.Content = new ObjectContent(typeof(object),new object(),new JsonMediaTypeFormatter());

                return response;
            });
    }
}