WebApi .Net – Add DelegatingHandler to Get Request Body

Out of the box, WebApi pipeline bind request body to parameter, therefore WebApi Controller (which inherit from ApiController) `Request.Content` object is empty.

For example, passing this json in the request body:

[
    {
        "Name": "Test",
        "Status": "C",
    }
]

Will bind it to WebApi Controller’s parameter, however, `Request.Content` object is empty.

Overcome this issue by creating `DelegatingHandler` to add request body back.

RequestHandler.cs

using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;

namespace QC
{
    public class RequestHandler : DelegatingHandler
    {
        protected override async Task SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            // Request body stream is emptied when WebApi bind request body to parameter, here we add original request body back so we can access it
            if (request.Content != null)
            {
                string body = await request.Content.ReadAsStringAsync();
                request.Properties["body"] = body;
            }

            return await base.SendAsync(request, cancellationToken);
        }
    }
}

Register in WebApiConfig.

WebApiConfig.cs

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.MessageHandlers.Add(new RequestHandler());
    }
}

Viola! `Request.Content` contains request body.

Code is from here.