Blog (pg. 18)

If you develop ASP.NET websites, you are probably aware that instead of using the built in Visual Studio Web Server (Cassini) for debugging, you can use IIS. If you have configured this for your project, Visual Studio creates a virtual directory in IIS and pressing F5 to debug won't start the built in server but will instead attach to the IIS website. Using IIS over Cassini has several advantages, however, it still doesn't allow you to edit the source while you browse the site and virtual directories can be a pain when the live site will be running from root. I prefer to leave these project settings alone and instead add an entirely new site in IIS, pointing at the codebase. This gives you more control over how the development site can be accessed and you can configure each site to use different SSL certificates, filter on host header values etc. This allows easy browsing of the latest version of the development site, and allows you to quickly make changes to the source code, recompile and refresh. Since you are doing all of this outside of the debugger you can edit source code while keeping an eye on how the changes are affecting the site. The only problem with this is if you are in the middle of using the site and you find a bug that you need to trace using the debugger, which of course isn't running in the current context. You can overcome by using the 'Debug > Attach to Process' menu and then selecting w3wp.exe. This will attach to the IIS process to and Visual Studio will load the debug symbols for the sites you are running, thus allowing you to set breakpoints in the code which will be fired by any browser triggering that line of code (also useful when you are testing accross multiple browsers). This is quite a few keystrokes to get the debugger up and running, but fortunately Visual Studio allows you to create macros and assign shortcuts to them. I found a tutorial on how to create a macro that will attach to IIS and how to set up the shortcut. I set up my shortcut key as CTRL+0 which is an easy sequence to remember. The macro that is listed on the above link did not work on my machine, because I am on a domain. I edited the script to tidy it up and to make it more robust, below:

Option Strict Off
Option Explicit Off
Imports System
Imports EnvDTE
Imports EnvDTE80
Imports EnvDTE90
Imports System.Diagnostics

Public Module AttachToIIS
    Sub Attach()
        Try
            Dim dbg2 As EnvDTE80.Debugger2 = DTE.Debugger
            Dim trans As EnvDTE80.Transport = dbg2.Transports.Item("Default")
            Dim dbgeng(3) As EnvDTE80.Engine
            dbgeng(0) = trans.Engines.Item("Managed")
            dbgeng(1) = trans.Engines.Item("Native")
            dbgeng(2) = trans.Engines.Item("T-SQL")

            Dim proc2 As EnvDTE80.Process2 = dbg2.GetProcesses(trans, Environment.MachineName).Item("w3wp.exe")
            proc2.Attach2(dbgeng)
        Catch ex As System.Exception
            MsgBox(ex.Message)
        End Try
    End Sub
End Module

If you get the error 'Invalid Index' it generally means that IIS has not loaded the application since a recompile, so you need to refresh the page in your browser first to reload it.

If you have defined extension methods to your entities in your BLL, (for example to format the output, or amalgamate some result) you may wish to display the return value of the extension method in a bound control, such as an ASP.NET GridView. In order to access an extension method, you have to import the containing namespace into the codefile you are working with. The problem is that the bindings are being evaluated by the DataBinder, so even if you import the namespace using the @import directive into the page, the extension methods are only available to your code-infront code blocks, not the ASP.NET DataBinder. In order to achieve this goal, you should Import the namespace as above using @import and instead of using a BoundField, use a TemplateField (but don't use Eval or Bind), simply cast the Container.DataItem back to the extended type and manually add the call to the extension method.

<%@ Import Namespace="eCommerceFramework.BLL.EntityExtensions" %>

---------------

<asp:TemplateField HeaderText="Price">
        <ItemTemplate>
                <%# FormatCurrency(DirectCast(Container.DataItem, DDL.DTOs.ShopBundle).TotalPrice(),2) %>
        </ItemTemplate>
</asp:TemplateField>

Generally speaking, I wouldn't imagine you would be 2 way data-binding on an extension method, but if you need to make the value retreivable, put it into a runat="server" control (label/textbox) and give it an ID you can use for FindControl.

The regular expressions engine provided by the .NET Framework includes a new feature known as 'balancing groups'. This feature allows you to increment/decrement the match count of a named capturing group by giving the group a positive and negative match context. You can then test to see you have an equal number of matches, by testing if the group has a value (i.e. an effective zero result means the group was balanced). You can include this syntax in your match pattern, so that only the balanced result is considered a match. Microsoft don't really go into this much and only show a small example of matching opening and closing paranthesis. In my case, I wanted to match a specific chunk of HTML code in a file and then find the closing tag to matching the name of the opening tag. For example:

<div>
  <div class="targetContent">
   Something in here
   <div> Something else in here</div>
  </div>
</div>

Using standard regular expressions, searching for <div class="targetContent"> to </div> can work in two ways. Non-greedy mode, matches on the </div> of the inner div. In greedy mode, it matches all the way to end of the outer div. What I wanted to do, is match on the last </div> that makes the tags balance, which can be done using balancing groups! C# Code:

pattern = "<div class=\"targetContent\">.*?((?<TAG><div).*?(?<-TAG></div>))?(?(TAG)(?!))</div>";

Effectively, what the expression does is:

1. Start the match from the div with class="targetContent"
2. Match any internal content
3. Whenever it encounters another div tag, it increments the TAG count
4. Match any nested content
5. Whenever it encounters another closing div tag, it decrements the TAG count
6. It becomes a match when the tag count is equal
7. Finally match on the closing tag of our outer div

This can be applied to any XML style markup, where you have the notation of opening and closing tags.

The standard LINQ .Distinct() function will pass your IEnumerable items to the 'default comparer' to differenciate the items. If your IEnumerable contains objects of an arbitrary class you would ordinarily have to create a IEqualityComparer to compare the relavent property of each instance. This seems like too much work just to simply remove objects that have a duplicate property value. I came up with a workaround for this using the 'group' keyword to group your objects by the target property and to then select the first record from each group, using the 'First' extension. C# Example:

   var distinctByWeekNum = from e in allUserEntries
                           group e by e.WeekNumber into g
                           select g.First();

The above example basically selects all objects that are distinct based on the 'WeekNumber', by first grouping items with the same 'WeekNumber' together and then selecting only the first item from each group (thus dropping any duplicates).

If you use the ASP.NET AJAX script manager with a service reference to a local WCF service, then you may encounter problems when using HTTPS on the page. If you have not configured your service for use with HTTPS you will most likely receive 'xyzService is not defined' errors in your Javascript. This is because when you add a service reference to '~/Services/xysService.svc' the AJAX Script Manager will import '~/Services/xyzService.svc/js' (or '~/Services/xyzService.svc/jsdebug') to define the prototypes for calling the service. This will return a '404 - Page Not Found' error when using the HTTPS protocol. In order to register the service for use over HTTPS you need to create a configured binding for this:

  <bindings>
     <webHttpBinding>

       <binding name="webHttpsBinding">
         <security mode="Transport"></security>

       </binding>

     </webHttpBinding>

   </bindings>

<services>
    <service name="WebNs.xyzService">
    <endpoint address="" behaviorConfiguration="WebNs.xyzServiceAspNetAjaxBehavior"
     binding="webHttpBinding" bindingConfiguration="webHttpsBinding" contract="WebNs.xyzService" />
   </service>

This configures your service to serve up over HTTPS. Make sure you add the HTTPS binding in IIS for this to work!