asp.net core - Getting hold of raw POST data when using [FromBody]

Question

I have a controller running on ASP.NET Core 1.0 RC2 and I'd like to dump the raw POST data out to telemetry as ApplicationInsights doesn't do this for you. My code looks like this

[HttpPost]
[Produces("application/json")]
public IActionResult Post([FromBody] RequestClass RequestData)
{
    var stream = this.HttpContext.Request.Body;
    stream.Position = 0;
    using (var reader = new StreamReader(stream))
    {
        string body = reader.ReadToEnd();
        Telemetry.TrackTrace(body, Microsoft.ApplicationInsights.DataContracts.SeverityLevel.Information);
    }
    return Ok();
}

But the string "body" always comes up empty. If I remove the [FromBody] decoration from the function signature, then this code works, but the RequestData object only contains null, which isn't what I want.

The only thing I can think of is converting RequestData back to a Json string, but this feels clunky and slow.

(EDIT: The POST data is Json)

Answer 1

You need to enable buffering the request body: services.Configure<FormOptions>(options => options.BufferBody = true); https://github.com/aspnet/HttpAbstractions/blob/dev/src/Microsoft.AspNetCore.Http/Features/FormOptions.cs#L20