How to read request body in OnActionExecuting(ActionExecutingContext context) in IActionFilter Asp.net core

Question

I am sending AES encrypted request body to controller following is a sample:

(using crypto-js) 
{body: "U2FsdGVk186Jj7LySqT966qTdpQZwiR+wR0GjYqBzR4ouFAqP8Dz8UPPTv"}

I have created action filter, so whenever the request is posted I can decrypt the request in action filter than pass the decrypted request to the desired controller.

request after decryption :

{Name: "admin123" }

so how to get encrypted request body in action filter? and how to pass decrypted request body to the controller

I have tried WEB API in ASP.NET core StreamReader but it is returning an empty string

I want to pass decrypted request body to the controller

filter

public void OnActionExecuting(ActionExecutingContext context)
{
    var req = context.HttpContext.Request;
    using (StreamReader reader = new StreamReader(req.Body, Encoding.UTF8, true, 1024, true))
    {
        bodyStr = reader.ReadToEnd();
    }
    req.Body.Position = 0;
}

controller

[HttpPost("[action]")]
public async Task<string> MyControllerName(InfoReq info)
{

}

class

public class InfoReq 
{
    public string Name{ get; set; }
}

Solution 1

Here you need to go for the middleware approach.Read the documentation Middleware if you want to read stream you must have to request.EnableRewind().because of Request. body is a read and forward only stream that doesn't support reading the stream a second time.

 request.EnableRewind();

after reading apply your logic and after that the request you need to add original stream back on the Response. Body

public void OnActionExecuting(ActionExecutingContext context)
   {              
    var request = context.HttpContext.Request;
     try
        {
            request.EnableRewind();
            using (StreamReader reader = new StreamReader(request.Body))
            {
                return reader.ReadToEnd();
            }
        }
        finally
        {
            request.Body = request; 
        }
        context.Request.Body.Position = 0
        return string.Empty;
    }

You should have to set stream position zero(0) request.Body.Position = 0 . Otherwise, you will get empty body exception.

Solution 2

You can use :

var body = context.ActionArguments["info"] as InfoReq ;

Comments

[Royi Namir]

This is the correct answer. @downvoter. care to comment ?

[suchoss]

I agree that this works. I was wondering how is it possible. But then I looked at the lifecycle of action filters and there I saw it. ActionFilter goes after Model binding therefore Body stream has been already read and data are already parsed. Source: docs.microsoft.com/en-us/aspnet/core/mvc/controllers/…