need to grab the contents of clientdependencycoremoduleresponsefilterstream - Extending Umbraco

Topic author was deleted

Jun 24, 2013 @ 14:36

Need to grab the contents of ClientDependency.Core.Module.ResponseFilterStream

This is a difficult one so apologies ahead of time. The following piece of code works in v4, but not v6 inside an HttpModule.

ResponseCaptureStream filter = app.Response.Filter as ResponseCaptureStream;              

if (filter != null)
{
  //filter is null for v6 not v4.
}

The main differences I can find between v4 and v6 is the output filtering is the filter type:

In v4 the type is: System.Web.HttpResponseStreamFilterSink

In v6 the type is: ClientDependency.Core.Module.ResponseFilterStream

In v6, 'filter' is null because it fails a cast.

What I'm truly after is the final HTML on every request. I don't actually need to perform my own filtering. Any suggestions on how to read the stream?

The ResponseCaptureStream class is as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Text;
using System.IO;

namespace FastCache
{
    public class ResponseCaptureStream : Stream
    {
        private readonly Stream _streamToCapture;
        private readonly Encoding _responseEncoding;

        private string _streamContent;
        public string StreamContent
        {
            get { return _streamContent; }
            private set
            {
                _streamContent = value;
            }
        }

        public ResponseCaptureStream(Stream streamToCapture, Encoding responseEncoding)
        {
            _responseEncoding = responseEncoding;
            _streamToCapture = streamToCapture;
        }

        public override bool CanRead
        {
            get { return _streamToCapture.CanRead; }
        }

        public override bool CanSeek
        {
            get { return _streamToCapture.CanSeek; }
        }

        public override bool CanWrite
        {
            get { return _streamToCapture.CanWrite; }
        }

        public override void Flush()
        {
            _streamToCapture.Flush();
        }

        public override long Length
        {
            get { return _streamToCapture.Length; }
        }

        public override long Position
        {
            get
            {
                return _streamToCapture.Position;
            }
            set
            {
                _streamToCapture.Position = value;
            }
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            return _streamToCapture.Read(buffer, offset, count);
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            return _streamToCapture.Seek(offset, origin);
        }

        public override void SetLength(long value)
        {
            _streamToCapture.SetLength(value);
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            _streamContent += _responseEncoding.GetString(buffer);
            _streamToCapture.Write(buffer, offset, count);
        }

        public override void Close()
        {
            _streamToCapture.Close();
            base.Close();
        }
    }

}

I have tried to simply extend the ClientDependency class to no avail.

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Phil Harvey 2 posts 92 karma points

Jun 24, 2013 @ 14:58

The underlying type of Filter should always be a Stream, so can you just do...

Stream filter = app.Response.Filteras Stream;              

if(filter !=null)
{
  //do work
}

The constructer for ResponseCaptureStream takes a Stream, so should be able to cope with it.

System.Web.HttpResponseStreamFilterSink and ClientDependency.Core.Module.ResponseFilterStream both derive from Stream.

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Lee Kelleher 4026 posts 15836 karma points MVP 13x admin c-trib

Jun 24, 2013 @ 15:05

The approach that I take on a few of my packages that make use of the Response.Filter stream is outlined in this blog post:

http://www.west-wind.com/weblog/posts/2009/Nov/13/Capturing-and-Transforming-ASPNET-Output-with-ResponseFilter

See my code examples for SafeMailLink (here) and Shortcodes (here). Not sure if this approach is 100% applicable to your issue though - sorry.

Cheers, Lee.

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Comment author was deleted

Jun 24, 2013 @ 15:10

A bit more code to chew on:

public void Init(System.Web.HttpApplication _app)
        {
            if (enabled)
            {
                app = _app;
                _app.ResolveRequestCache += new EventHandler(Start);
                _app.PreSendRequestContent += new EventHandler(Finish);
            }
        }

private void Start(Object sender, EventArgs e)
{
   app.Response.Filter = new ResponseCaptureStream(app.Response.Filter, app.Response.ContentEncoding);                    
}

private void Finish(object sender, EventArgs e)
{
   ResponseCaptureStream filter = app.Response.Filter as ResponseCaptureStream;
   if (filter != null){
     //never make it here in v6
     string responseText = filter.StreamContent;// this is how I'm grabbing the 'final' output
   }
}

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Phil Harvey 2 posts 92 karma points

Jun 24, 2013 @ 15:20

I do it slightly differently, here's some code. I can't remember why I stick the StreamWatcher in the context items, but there was a good reason (probably haha).

private void Start(Object sender,EventArgs e)
{
 var watcher = new StreamWatcher(context.Response.Filter); context.Context.Items["StaticCacheModule_watcher"] = watcher; context.Response.Filter = watcher;  
}

private void Finish(object sender,EventArgs e)
{
 var watcher = context.Context.Items["StaticCacheModule_watcher"] as StreamWatcher; if (watcher != null) {
 string value = watcher.ToString().Trim();
 }
}

    public class StreamWatcher : Stream
    {
        private Stream _base;
        private MemoryStream _memoryStream = new MemoryStream();

        public StreamWatcher(Stream stream)
        {
            _base = stream;
        }

        public override void Flush()
        {
            _base.Flush();
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            return _base.Read(buffer, offset, count);
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            _memoryStream.Write(buffer, offset, count);
            _base.Write(buffer, offset, count);
        }

        public override string ToString()
        {
            return Encoding.UTF8.GetString(_memoryStream.ToArray());
        }

        #region Rest of the overrides
        public override bool CanRead
        {
            get { return _base.CanRead; }
        }

        public override bool CanSeek
        {
            get { return _base.CanSeek; }
        }

        public override bool CanWrite
        {
            get { return _base.CanWrite; }
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            return _base.Seek(offset, origin);
        }

        public override void SetLength(long value)
        {
            _base.SetLength(value);
        }

        public override long Length
        {
            get { return _base.Length; }
        }

        public override long Position
        {
            get
            {
                return _base.Position;
            }
            set
            {
                _base.Position = value;
            }
        }
        #endregion
    }

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Comment author was deleted

Jun 24, 2013 @ 16:16

I'm spinning up your code now, thanks for the lead

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Comment author was deleted

Jun 24, 2013 @ 16:20

Brilliant, it seems to be working :) Thank you so much :)

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Need to grab the contents of ClientDependency.Core.Module.ResponseFilterStream