Five common mistakes for ASP.NET (MVC) accesing resources : css, js, images, ajax

To have once for all the link to show to people, because too much makes the same error again and again.

(From here – you can use ResolveUrl or Url.Content – it’s the same for me. I use ResolveUrl because I used first …)

Case 1 The image does not display

Please check you have the following :

<img src='<%= ResolveUrl("~/Content/images/YOURIMAGE.jpg" )%>'  alt="image" style="border:0" />

Case 2 The css does not show

Please check you have the following :

<%= string.Format("<link href='{0}' type='text/css' rel='stylesheet' />", ResolveUrl("~/Content/your.css")) %>


<style type="text/css">
@import '<%= ResolveUrl("~/Content/your.css") %>';


Case 3 The js does not execute (undefined error)

Please check you have the following :

<script type="text/javascript" src='<%= ResolveUrl("~/Scripts/yourjs.js")%>'></script>

Case 4 The js does execute in aspx page, but did not execute under js file

Please check you DO NOT have the following


in the js file. The js file is not interpreted by the same engine as aspx, so can not interpret asp.net tags. Instead , add a parameter to your function : the path.

Simple example : Let’s say in aspx you have :

<script type=”text/javascript”>

function Generate(){

window.open(‘<% Url.Action(“About”)%>’);


and you call Generate();

When you put in .js file, please put this :

function Generate(url){


and call like this :

Generate('<% Url.Action(“About”)%>');

Case 5 The ajax request gives you a 404 error.

Please ensure that you have

<%= ResolveUrl("~/path”)%>

and not


Bonus 1: T4MVC , http://mvccontrib.codeplex.com/releases

Bonus 2: Edit the project file and put <MvcBuildViews>true</MvcBuildViews>

( short url: http://bit.ly/asp5Mistakes)

Html Agility Pack

This is the ultimate reference of reading web pages.

IF you want to do it yourself , you can try with WebRequest , http://msdn.microsoft.com/en-us/library/system.net.webrequest.aspx . But not all HTML is an XML – so you must find a method to parse. But am I the only one ?No – so I found the  HTML Agility Pack , http://www.codeplex.com/htmlagilitypack , that knows how to transform HTML in XML. The code is easy :

HtmlWeb hw = new HtmlWeb();
hw.AutoDetectEncoding = true;
HtmlDocument  doc = hw.Load(Url);
HtmlNode NodeRoot = doc.DocumentNode;

And from NodeRoot you can start XPATH with SelectNodes . Try it – it is awesome!

Andrei Ignat weekly software news(mostly .NET)

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