ASP.NET webapi HttpResponseMessage with ExecuteReaderAsync C

我需要通过WebApi从Sql Server流式传输blob数据。

我不想在web服务器的内存中缓冲blob数据。

我有以下代码，但它不起作用——没有例外。

public class AttachmentController : ApiController
{
    public async Task<HttpResponseMessage> Get(int id)
    {
        using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
        {
            await connection.OpenAsync();
            using (var command = new SqlCommand("SELECT Content FROM [Attachments] WHERE ID = @ID", connection))
            {
                command.Parameters.AddWithValue("ID", id);
                using (SqlDataReader reader = await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess))
                {
                    if (await reader.ReadAsync())
                    {
                        using (Stream data = reader.GetStream(0))
                        {
                            var response = new HttpResponseMessage{Content = new StreamContent(data)};
                            //I get this from the DB else where
                            //response.Content.Headers.ContentType = new MediaTypeHeaderValue(attachment.ContentType);
                            //I get this from the DB else where
                            //response.Content.Headers.ContentLength = attachment.ContentLength;
                            return response;
                        }
                    }
                }
            }
            throw new HttpResponseException(HttpStatusCode.NotFound);
        }
    }
}

Fiddle写入以下错误作为回复：[Fiddler]ReadResponse（）失败：服务器没有返回对此请求的响应。

如何将内容从DB流式传输到http输出流，而不在内存中进行缓冲？