jesal gadhia » c#

How to parse Wordpress RSS feed using LINQ

Fri, 19 Mar 2010 05:32:28 +0000

Here’s a code snippet of parsing a typical Wordpress RSS feed using LINQ. Note, we have to skip the first image from the media element since that’s usually a gravatar of the author.

Everything else is pretty straight forward.

    private void BindBlogFeed()
    {
        XDocument doc = XDocument.Load("http://blogworkseverytime.wordpress.com/feed/");
        XNamespace content = "http://purl.org/rss/1.0/modules/content/";
        XNamespace media = "http://search.yahoo.com/mrss/";

        var query = (from feed in doc.Descendants("item")
                     orderby DateTime.Parse(feed.Element("pubDate").Value) descending
                     select new
                     {
                         Title = feed.Element("title").Value,
                         Description = HttpUtility.HtmlDecode(feed.Element("description").Value),
                         Content = HttpUtility.HtmlDecode(feed.Element(content.GetName("encoded")).Value),
                         Image = (from img in feed.Elements(media.GetName("content"))
                                  where img.Attribute("url").Value.Contains("gravatar") == false
                                  select img.Attribute("url").Value).FirstOrDefault() ?? "",
                         Link = feed.Element("link").Value,
                         Date = DateTime.Parse(feed.Element("pubDate").Value).ToShortDateString()
                     });

        lvFirstBlogFeed.DataSource = query.Take(1).ToList();
        lvFirstBlogFeed.DataBind();

        lvRemainingBlogFeed.DataSource = query.Skip(1).ToList();
        lvRemainingBlogFeed.DataBind();
    }

How to Parse Twitter Usernames, Hashtags and URLs in C# 3.0

Wed, 06 May 2009 22:13:27 +0000

Lately I’ve been working on my pet project called Twime. So as part of that project, I wanted to add the ability to parse URLs, usernames and hashtags from the user’s Twitter timeline. Here’s how I went about doing that:

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

public static class HTMLParser
{
    public static string Link(this string s, string url)
    {
        return string.Format("{1}", url, s);
    }
    public static string ParseURL(this string s)
    {
        return Regex.Replace(s, @"(http(s)?://)?([\w-]+\.)+[\w-]+(/\S\w[\w- ;,./?%&=]\S*)?", new MatchEvaluator(HTMLParser.URL));
    }
    public static string ParseUsername(this string s)
    {
        return Regex.Replace(s, "(@)((?:[A-Za-z0-9-_]*))", new MatchEvaluator(HTMLParser.Username));
    }
    public static string ParseHashtag(this string s)
    {
        return Regex.Replace(s, "(#)((?:[A-Za-z0-9-_]*))", new MatchEvaluator(HTMLParser.Hashtag));
    }
    private static string Hashtag(Match m)
    {
        string x = m.ToString();
        string tag = x.Replace("#", "%23");
        return x.Link("http://search.twitter.com/search?q=" + tag);
    }
    private static string Username(Match m)
    {
        string x = m.ToString();
        string username = x.Replace("@", "");
        return x.Link("http://twitter.com/" + username);
    }
    private static string URL(Match m)
    {
        string x = m.ToString();
        return x.Link(x);
    }
}

So as you can see I’m using the new Extension Methods feature in C# 3.0.

Now I can simply just call the extension methods like this:

string tweet = "Just blogged about how to parse HTML from the @twitter timeline - http://jesal.us/blog/?p=132 #programming";
Response.Write(tweet.ParseURL().ParseUsername().ParseHashtag());

and the result should looks something like this:

Just blogged about how to parse html from the @twitter timeline – http://jesal.us/blog/?p=132 #programming

Just be sure to call ParseURL method before ParseUsername and ParseHashtag. The other two methods will add URLs to the usernames and hastags and you don’t want ParseURL to confuse those links with the original links present in the text.

This was inspired by Simon Whatley’s post about doing something similar using prototyping with JavaScript.

Calculate Shipping Cost Using UPS OnLine Tools

Sat, 21 Feb 2009 05:46:39 +0000

Before using this code, all you need to do is register for an UPS OnLine Tools account and then apply for a XML Access key using your developer key which you will receive after creating an account. After you get your access key, just plug your username, password and the key into the highlighted line below and you should be good to go!

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Text;
using System.Net;
using System.IO;
using System.Xml;

/// 
/// Summary description for ShippingCalculator
///

How To Clear All Items From Cache

Mon, 01 Sep 2008 23:00:50 +0000

if (Cache.Count > 0)
{
	string currentKey = string.Empty;
	System.Collections.IDictionaryEnumerator cacheContents =
	System.Web.HttpContext.Current.Cache.GetEnumerator();

	Response.Write(string.Format("Following {0} cache keys were cleared:

", Cache.Count));

	while (cacheContents.MoveNext())
	{
		currentKey = cacheContents.Key.ToString();
		Response.Write(currentKey + "
");
		System.Web.HttpContext.Current.Cache.Remove(currentKey);
	}
}
else
{
	Response.Write("Nothing to clear. Cache is empty.");
}

How to easily parse HTML without RegEx

Tue, 06 May 2008 16:50:04 +0000

I recently discovered an absolutely amazing HTML parsing library for .NET called HtmlAgilityPack. It completely takes away the pain of parsing complicated HTML with regular expressions.

Here’s a very simple example of what you could do with it – I’m just extracting inner HTML from any element inside a HTML file which has a css class called “scrape” assigned to it:

using HtmlAgilityPack;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        HtmlDocument doc = new HtmlDocument();
        doc.Load(Server.MapPath(filePath));
        Parse(doc.DocumentNode);
    }
    private void Parse(HtmlNode n)
    {
        foreach (HtmlAttribute atr in n.Attributes)
        {
            if (atr.Name == "class" && atr.Value == "scrape")
            {
                Response.Write(n.InnerHtml);
            }
        }

        if (n.HasChildNodes)
        {
            foreach (HtmlNode cn in n.ChildNodes)
            {
                Parse(cn);
            }
        }
    }
}

That’s just a very small part of what it could do. I’ll expand upon this and post a few more examples in the future showing some interesting things you could do with this.

How To Create A Random Fact Generator Using XML

Thu, 24 Apr 2008 00:03:19 +0000

This is a simple little random fact generator which will show a new fact every time the page loads. After the initial load it will store the XML in the cache until the file is changed again.

XML: (Facts.xml)

xml version="1.0" encoding="utf-8" ?>
<facts>
  <fact>
    The numbers '172' can be found on the back of the U.S. $5 dollar
    bill in the bushes at the base of the Lincoln Memorial.
  fact>
  <fact>
    President Kennedy was the fastest random speaker in the world
    with upwards of 350 words per minute.
  fact>
  <fact>
    In the average lifetime, a person will walk the equivalent of 5
    times around the equator.
  fact>
    .
    .
    .
facts>

Code: (RandomFact.ascx.cs)


using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Caching;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.IO;
using System.ComponentModel;
using System.Drawing.Design;
 
public partial class _controls_RandomFact : System.Web.UI.UserControl
{
    private string _xmlDataSource;
    [UrlProperty()]
    public string XMLDataSource
    {
        get { return _xmlDataSource; }
        set { _xmlDataSource = value; }
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        litFact.Text = getRandomFact();
    }
    private string getRandomFact()
    {
        Random rndIndex = new Random();
        XmlDocument xmlDocFacts = new XmlDocument();
        string strFact = string.Empty;
 
        try
        {
            if (Cache["xmlDocFacts"] != null)
            {
                xmlDocFacts = (XmlDocument)Cache["xmlDocFacts"];
            }
            else
            {
                xmlDocFacts.Load(Server.MapPath(XMLDataSource));
                Cache.Insert("xmlDocFacts", xmlDocFacts, new CacheDependency(Server.MapPath(XMLDataSource)));
            }
 
            XmlNodeList xmlNodesMessage = xmlDocFacts.SelectNodes("//fact");
            int rnd = rndIndex.Next(0, xmlNodesMessage.Count);
            strFact = Server.HtmlEncode(xmlNodesMessage[rnd].InnerText);
        }
        catch (Exception ex)
        {
            strFact = string.Format("Error: {0}", ex.Message);
        }
 
        return strFact;
    }
}

Usage: (Default.aspx)

<uc1:RandomFact ID=”RandomFact1″ runat=”server” XMLDataSource=”App_Data/Facts.xml” />

How to manipulate video in .NET using ffmpeg (updated)

Tue, 22 Apr 2008 18:25:55 +0000

Based on the reader comments on my previous entry on this topic I was able to fix some of the issues that others were experiencing.

I changed how the output is read, instead of reading the entire stream at once, its now read line-by-line as ErrorDataReceived and OutputDataReceived events are raised. Also added an extra option in the command line (-ar 44100) to explicitly set the audio frequency to default since it wasn’t being applied to some video formats resulting in an error. And lastly, the console window is now set as hidden.

private void ConvertVideo(string srcURL, string destURL)
{
    string ffmpegURL = “~/project/tools/ffmpeg.exe”;
    DirectoryInfo directoryInfo = new DirectoryInfo(Path.GetDirectoryName(Server.MapPath(ffmpegURL)));

    ProcessStartInfo startInfo = new ProcessStartInfo();
    startInfo.FileName = Server.MapPath(ffmpegURL);
    startInfo.Arguments = string.Format(“-i \”{0}\” -aspect 1.7777 -ar 44100 -f flv \”{1}\”", srcURL, destURL);
    startInfo.WorkingDirectory = directoryInfo.FullName;
    startInfo.UseShellExecute = false;
    startInfo.RedirectStandardOutput = true;
    startInfo.RedirectStandardInput = true;
    startInfo.RedirectStandardError = true;
    startInfo.CreateNoWindow = true;
    startInfo.WindowStyle = ProcessWindowStyle.Hidden;

    using (Process process = new Process())
    {
        process.StartInfo = startInfo;
        process.EnableRaisingEvents = true;
        process.ErrorDataReceived += new DataReceivedEventHandler(process_ErrorDataReceived);
        process.OutputDataReceived += new DataReceivedEventHandler(process_OutputDataReceived);
        process.Exited += new EventHandler(process_Exited);

        try
        {
            process.Start();
            process.BeginErrorReadLine();
            process.BeginOutputReadLine();
            process.WaitForExit();
        }
        catch (Exception ex)
        {
            lblError.Text = ex.ToString();
        }
        finally
        {
            process.ErrorDataReceived -= new DataReceivedEventHandler(process_ErrorDataReceived);
            process.OutputDataReceived -= new DataReceivedEventHandler(process_OutputDataReceived);
            process.Exited -= new EventHandler(process_Exited);
        }
    }
}
void process_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
    if (e.Data != null)
    {
        lblStdout.Text += e.Data.ToString() + “
”;
    }
}
void process_ErrorDataReceived(object sender, DataReceivedEventArgs e)
{
    if (e.Data != null)
    {
        lblStderr.Text += e.Data.ToString() + “
”;
    }
}
void process_Exited(object sender, EventArgs e)
{
    //Post-processing code goes here
}

How to unzip files in .NET using SharpZipLib

Wed, 12 Mar 2008 06:30:22 +0000

SharpZipLib is a great open source library for handeling all kinds of gzip/zip compression/decompression. More Info – http://www.icsharpcode.net/OpenSource/SharpZipLib/

In the following example I’m passing the HtmlInputFile object directly into the ZipInputStream to decompress the PostedFile and save its contents on the server.

.
.
using System.IO;
using ICSharpCode.SharpZipLib.Zip
.
.
private void UnzipAndSave(HtmlInputFile objFileUpload)
{
    ZipInputStream s = new ZipInputStream(objFileUpload.PostedFile.InputStream);

    ZipEntry theEntry;
    string virtualPath = "~/uploads/";
    string fileName = string.Empty;
    string fileExtension = string.Empty;
    string fileSize = string.Empty;

    while ((theEntry = s.GetNextEntry()) != null)
    {
        fileName = Path.GetFileName(theEntry.Name);
        fileExtension = Path.GetExtension(fileName);

        if (!string.IsNullOrEmpty(fileName))
        {
            try
            {
                FileStream streamWriter = File.Create(Server.MapPath(virtualPath + fileName));
                int size = 2048;
                byte[] data = new byte[2048];

                do
                {
                    size = s.Read(data, 0, data.Length);
                    streamWriter.Write(data, 0, size);
                } while (size > 0);

                fileSize = Convert.ToDecimal(streamWriter.Length / 1024).ToString() + ” KB”;

                streamWriter.Close();

                //Add custom code here to add each file to the DB, etc.
            }
            catch (Exception ex)
            {
                Response.Write(ex.ToString());
            }
        }
    }

    s.Close();
}

How to manipulate video in .NET using ffmpeg

Wed, 12 Mar 2008 06:02:04 +0000

In this case I’m resizing the video and converting it to FLV format. For more ffmpeg commandline options - http://ffmpeg.mplayerhq.hu/ffmpeg-doc.html

private void ConvertVideo(string srcURL, string destURL)
{
    string ffmpegURL = "~/project/tools/ffmpeg.exe";
    DirectoryInfo directoryInfo = new DirectoryInfo(Path.GetDirectoryName(Server.MapPath(ffmpegURL)));

    ProcessStartInfo startInfo = new ProcessStartInfo();
    startInfo.FileName = Server.MapPath(ffmpegURL);
    startInfo.Arguments = string.Format("-i \"{0}\" -s 368x216 -aspect 1.7777 \"{1}\"", srcURL, destURL);
    startInfo.WorkingDirectory = directoryInfo.FullName;
    startInfo.UseShellExecute = false;
    startInfo.RedirectStandardOutput = true;
    startInfo.RedirectStandardInput = true;
    startInfo.RedirectStandardError = true;

    using (Process process = new Process())
    {
        process.StartInfo = startInfo;

        try
        {
            process.Start();
            StreamReader standardOutput = process.StandardOutput;
            StreamWriter standardInput = process.StandardInput;
            StreamReader standardError = process.StandardError;
            process.WaitForExit();

            lblError.Text = standardError.ReadToEnd();
            lblOutput.Text = standardOutput.ReadToEnd();
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
    }
}

Event Driven Developement using ASP.NET & C#

Sat, 16 Feb 2008 08:01:45 +0000

Until recently I wasn’t entirely familiar with the concepts of Event Driven Programming, Event Bubbling, etc. Being a .NET developer I’ve been exposed to events and delegates but I never really understood the concept in its entirety. Somehow I had a hard time readily finding good sources online focusing on event driven programming especially using ASP.NET/C#. But I had to get myself more familiarized with the concept since I need to use a lot of that in my current project. So after doing some digging I found couple of good links which explain the concept quite well -

Hope that helps.