How to manipulate response body in ASP.Net core Acton filter without affecting other middlewares?

[rbipin]

I have two endpoints and the result needs to be formatted differently for each endpoint
I'm manipulating the response body in OnResultExecuting in an Action Filter.
My API has a couple of middlewares that are also changing response status codes. Since my Action filter is already doing response.body.writeAsync. The middlewares are throwing error that the response has already started. Is there a work around to safely manipulate the response without affecting any other middlewares. The code snippet is given below.

      var response = context.HttpContext.Response;
            if (response.StatusCode != 200)
            {
                base.OnResultExecuting(context);
            }
            var result = context.Result as ObjectResult;
            var serializedContent = result.Value.Serialize();
            var data = Encoding.UTF8.GetBytes(serializedContent);
            response.Headers.Add("Content-Type", "application/xml");
            await response.Body.WriteAsync(data, 0, data.Length);
           base.OnResultExecuting(context);
`

[davidfowl]

Only one middleware can write to the response. You have a couple of options:

• Buffer the response. If you buffer the response in a middleware then that middleware can also flush the response to the output.
• The other middleware should no-op when the response has already started.

What middleware is in the pipeline?