Need to log asp.net webapi 2 request and response body to a database

I would recommend using a DelegatingHandler. Then you will not need to worry about any logging code in your controllers.

public class LogRequestAndResponseHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (request.Content != null)
        {
            // log request body
            string requestBody = await request.Content.ReadAsStringAsync();
            Trace.WriteLine(requestBody);
        }
        // let other handlers process the request
        var result = await base.SendAsync(request, cancellationToken);

        if (result.Content != null)
        {
            // once response body is ready, log it
            var responseBody = await result.Content.ReadAsStringAsync();
            Trace.WriteLine(responseBody);
        }

        return result;
    }
}

Just replace Trace.WriteLine with your logging code and register the handler in WebApiConfig like this:

config.MessageHandlers.Add(new LogRequestAndResponseHandler());

Here is the full Microsoft documentation for Message Handlers.

One of the option you have is using creating a action filter and decorating your WebApiController/ApiMethod with it.

Filter Attribute

public class MyFilterAttribute : System.Web.Http.Filters.ActionFilterAttribute
    {
        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            if (actionContext.Request.Method == HttpMethod.Post)
            {
                var postData = actionContext.ActionArguments;
                //do logging here
            }
        }
    }

WebApi controller

[MyFilterAttribute]
public class ValuesController : ApiController{..}

or

[MyFilterAttribute]
public void Post([FromBody]string value){..}

Hope this helps.

There are multiple approaches to generically handle Request/Response logging for every WebAPI method calls:

1. ActionFilterAttribute: One can write custom ActionFilterAttribute and decorate the controller/action methods to enable logging.

   Con: You need to decorate every controller/methods (still you can do it on base controller, but still it doesn't address cross cutting concerns.

2. Override BaseController and handle logging there.

   Con: We are expecting/forcing the controllers to inherit from a custom base controller.

3. Using DelegatingHandler.

   Advantage: We are not touching controller/method here with this approach. Delegating handler sits in isolation and gracefully handles the request/response logging.

For more indepth article, refer this http://weblogs.asp.net/fredriknormen/log-message-request-and-response-in-asp-net-webapi.