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Watching Craigslist

, 2 Jan 2009
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Show automatically updated search results from Craigslist on your desktop

Overview

Craigslist is a hugely popular website with free local listings for jobs, housing, and items for sale.

Trying to buy something on Craigslist is like a flock of seagulls going after one French fry. If something good gets posted, it might be gone before you get a chance to call. So do you scan new items every morning? What if you miss a day? There are hundreds of new items that get posted each day. 

I wanted a desktop window that would show me filtered search results from Craigslist and update them periodically.

Approach

Instead of sending Craigslist a server-side query, I decided to just get the Craigslist RSS feed and filter the results on the client-side. There are two advantages of this -- server changes don't break our code and we can watch other feeds in a similar way (for example, eBay).  At first, I made a general purpose feed monitor, but it got kind of abstract and complicated and I decided a Craigslist specific application would be nicer and easier to explain.

Interface

A listview is used to display results so I can sort by column (e.g. price or date).

MainForm.jpg

For most searches, just type some keywords and press enter to load the results. Double-clicking on an item in the results list will open it in a browser. Or you can just click on the "open item" button. The Category button will open the entire list in a browser. For more advanced searches, press the Advanced button.

Advanced.jpg

For email alerts, check the send email alerts box and setup an email address.

Email.jpg

Code 

Settings are saved and restored using XML serialize.

StreamWriter sw = new StreamWriter(path);
new XmlSerializer(obj.GetType()).Serialize(sw, obj);
sw.Close(); 

You gotta love C#. And when we load and parse the RSS feed, XML does the trick again.

XmlDocument feed = new XmlDocument();
feed.Load(GetUrl());
XmlNodeList nodes = feed.GetElementsByTagName("item");

foreach (XmlNode node in nodes)
{
    // get node info
    if (Match(info)
    // add to results
} 

Similar Tools

There are other similar programs out there but none of them provide free C# code so you can extend them.

Extending This

You could easily add multiple searches and a treeview control to expand titles into descriptions.  For this article, I decided to keep those features out.  The advanced search form could easily be expanded to allow excluded keywords and any-or-all keywords.

History

  • Dec 12, 2008: Original submission
  • Dec 13, 2008: Added email alerts
  • Dec 13, 2008: Updated source and demo project 
  • Dec 29, 2008: Updated source and demo projects 

License

This article, along with any associated source code and files, is licensed under The BSD License

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About the Author

milkplus
Software Developer Buzz Monkey Software
United States United States
David McClurg is a game programmer from Oregon, USA. He is currently interested in C#, xna for zune, and steering behaviors. When not coding, David enjoys tennis, kayaking, and botany.

Comments and Discussions

 
QuestionQuestion Pinmemberali_331014-Dec-12 3:57 
GeneralMy vote of 3 PinmemberinkcolorYui24-Mar-12 17:24 
QuestionNot working right!!! PinmemberMember 78875002-May-11 7:03 
AnswerRe: Not working right!!! Pinmembermilkplus2-May-11 9:11 
GeneralRe: Not working right!!! PinmemberMember 78875002-May-11 9:16 
GeneralRe: Not working right!!! Pinmembercoreyt5-Feb-13 18:55 
Question"My Ebay" Button Pinmemberardns28-Jun-10 23:37 
AnswerRe: "My Ebay" Button Pinmembermilkplus29-Jun-10 6:00 
GeneralAdding an email link in the email message PinmemberC# Friendly11-Oct-09 12:14 
GeneralRe: Adding an email link in the email message Pinmembermilkplus11-Oct-09 14:40 
Generalsearching multiple items PinmemberC# Friendly3-Oct-09 15:48 
GeneralRe: searching multiple items Pinmembermilkplus4-Oct-09 7:36 
GeneralRe: searching multiple items PinmemberC# Friendly11-Oct-09 11:59 
GeneralThe include files are for Watching eBay PinmemberJamesMMM29-Dec-08 10:45 
GeneralRe: The include files are for Watching eBay Pinmembermilkplus3-Jan-09 11:23 
GeneralRSS feed PinmemberTodd Smith13-Dec-08 10:57 
GeneralLocations Pinmemberoldpartz13-Dec-08 9:13 
GeneralRe: Locations PinmemberTodd Smith13-Dec-08 10:35 
GeneralRe: Locations Pinmemberoldpartz13-Dec-08 10:48 
GeneralRe: Locations PinmemberTodd Smith13-Dec-08 10:45 
GeneralRe: Locations Pinmemberoldpartz13-Dec-08 11:12 
GeneralVery nice article! Pinmemberthompsons13-Dec-08 7:23 

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