Once again, Scott Guthrie posted some more highly informative ASP.NET 2.0 information; this post being the first in a series featuring typed datasets.

Many people groan at the thought of using typed datasets because ‘purists’ feel that using them generates a lot of unnecessary code (among other things which I won’t discuss here.)  While this may be true, they are very useful for creating a very quick-n-dirty data access layer with almost no need to write SQL or ADO code.  In addition, getting ‘free’ strongly typed code (intellisense = good) makes me think that typed datasets are well worth looking at!

• Part 1: Building a DAL using Strongly Typed TableAdapters and DataTables in VS 2005 and ASP.NET 2.0
• Part 2: Building Our Master Pages and Site Navigation Structure

The W3C has introduced a MIME type for XHTML documents. This new MIME type is application/xhtml+xml. The W3C recommends that you use the application/xhtml+xml MIME type when serving XHTML documents, because XHTML pages should be interpreted in a stricter way than legacy HTML pages.

You can serve an ASP.NET page with a particular MIME type by including the ContentType attribute in a page directive. For example, including the following directive at the top of an ASP.NET page causes the page to be served as application/xhtml+xml.

<%@ ContentType="application/xhtml+xml" %>

Doing so will force you to make sure your web pages are valid XHTML files because they’ll break if your code is sloppy.

Ok, that’s great… except for the fact that Internet Explorer will now display your web site as an XML file instead of an HTML file!  There are a few work-arounds for this, but the easiest one for ASP.NET 2.0 sites seems to be this simple addition to the Global.asax file:

<script runat="server">

    Sub Application_PreSendRequestHeaders(ByVal s As Object, _
      ByVal e As EventArgs)
        If Array.IndexOf(Request.AcceptTypes, _
          "application/xhtml+xml") > -1 Then
            Response.ContentType = "application/xhtml+xml"
        End If
    End Sub

</script>

I’ve had a small obsession with learning about web standards recently, mostly because a world of truly standards-compliant browsers is a world where web developers don’t have to test their web sites on all the latest (and very quirky) browsers.

Along with attaining standards compliance comes meeting the needs of those with disabilities, such as those who are visually impaired or blind.  The Internet is a wonderful place full of nearly unlimited amounts of information and it would be a shame if your web site was preventing people from tapping into part of it!

So how do you make your web site standards compliant and make sure it caters to the needs of those with disabilities?   Well, this MSDN article does a great job of explaining all of this:

MSDN: Building ASP.NET 2.0 Web Sites Using Web Standards

One thing I like about the article is that even though it is from Microsoft, it doesn’t hide the fact that Internet Explorer isn’t quite up-to-snuff when it comes to meeting some of the stricter standards (like XHTML Strict).  The article also offers some work-arounds for some of the problems one will encounter with trying to make a site fully standards compliant.

In addition to the MSDN article, these two articles may also come in handy when designing more usable web sites:

• Trace Research and Development: Designing More Useable Web Sites
• UseIt.com: Accessible Design for Users With Disabilities
• Section 508: The Road to Accessibility
• W3C Web Accessibilty Initiative

As you'll read in some of these web sites, there are laws that require a web site to be accessible (Section 508) when working with government agencies.

As a site designer (in addition to being a developer), one thing I’m finding challenging about creating accessible site designs for users with disabilities is that it greatly limits what I can do with my site in terms of formatting and using scripting technologies like DHTML.   It seems to me that when designing a site for a client that has business requirement for designing an accessible site, it may be best to either create a text-only version of the web site or make sure there is a CSS style sheet that can display the web site without all the glitz.  This also means that dynamic DHTML menus have to go away in favor of more static hyperlinks and sitemaps.

One of the biggest pains is testing a web application is testing the User Interface (UI).  When you’re trying to track-down a bug that occurs after clicking through 20 different links on your site and having to fill-out multiple forms, you’ll soon start pulling your hair-out but might have thought there was no other way around doing this manual testing.

For those of you who can’t afford Visual Studio Team System 2005 (which has a UI recording tool), there is still hope!  Alex Furman created an incredible application called the SW Explorer Automation Designer that can automate UI tests for you and its free!

I just downloaded it and ran through the same scenario that is shown in the online demonstration.  I must say that I’m impressed and I wish I would’ve discovered this tool a long time ago.  Granted, it only works with Internet Explorer, but that’s ok for me as most of the applications I build target IE as the primary browser.  I highly recommended going through the demo step-by-step (keep your cursor over the ‘pause’ button!) to learn how to use the tool.

Setting-up a test takes a little bit of time, but I think it’s worth taking a few minutes up-front to save you many minutes (or perhaps hours or days!) when testing your site. If you'd like to integrate your SWE tests with your NUnit tests, TestingReflections.com has an article explaining how to do that (in C#, of course :'( )

Seems that a new HTML tag pop-ups every once in a while that I wasn’t aware of.  Today it’s the <label> tag.

So what is the label tag for? Using the label allows the user to click on the text associated with a form control instead of having to click on the radio button, check box, select box, etc.

Granted, this isn’t likely to be hugely useful to you, but I know I’ve often found it convenient to simply click on text next to a check box (or similar form field) when I’m in a hurry, hence it increases the usability of your page.

However, if an accessible web site for the visually impaired, using the label tag helps those who visit your site with a screen reader to associate a fields label with the field that it belongs to.

How do you use it?  Here is how:

<label for="radio1">This Radio Button 1 has a label associated with it.</label>

<input type="radio" value="Selected" name="Radio" id="radio1">

One thing I find convenient about the label is that I can now create a CSS style for the HTML label tag and know that all the field labels will be formatted the same. I no longer have to create a <span> or <div> tag with a special CSS class for field labels.

However, in ASP.NET, I could envision the label not working as it’s supposed to in many cases because it’s often hard to predict the name of the field controls.  For example, if I have a textbox with an ID of “txtFirstName” which is nested in a User Control, which is nested in a Page, which is nested in a Master Page, ASP.NET will rename the control and it’s ID to something like “ctl001 MyMasterPage MyPage MyUserControl txtFirstName.”

With that in-mind, the functionality of the label control might be limited in ASP.NET applications, but at least it provides a new tag to bind CSS to! :-)

Update - 01/06/2006

Those guys at Microsoft are no dummies... they made sure the ASP.NET 2.0 Framework produces standards compliant and accessible code.  To assure that your ASP.NET 2.0 form fields are properly labeled, you must use the AssociatedId property for the ASP.NET Label control in order to make the .NET Framework spew the correct HTML:

    <table>
    <tr>
        <td><asp:Label AssociatedControlID="txtFirstName"
          runat="server">First Name:</asp:Label></td>
        <td><asp:TextBox ID="txtFirstName" runat="server" /></td>
    </tr>
    <tr>
        <td><asp:Label AssociatedControlID="txtLastName"
          runat="server">Last Name:</asp:Label></td>
        <td><asp:TextBox ID="txtLastName" runat="server" /></td>
    </tr>
    </table>

The following is Fritz Onion’s posting on Complex data binding expressions in ASP.NET, converted into VB.NET:

I often find when using templated data-bound controls (in either ASP.NET 1.1 or 2.0) that my expressions become rather difficult to understand because of the need to fit all of your logic into a single expression. For example, I have seen databound expressions that look something like:

< asp : TemplateField HeaderText ="SomeColumn">
  < ItemTemplate >
    <% # (( bool )Eval( "foo" )) ? Eval( "bar" ) : ((( bool )Eval( "quux" )) ? Eval( "a" ) : Eval( "b" )) %>
  </ ItemTemplate >
</ asp : TemplateField >

Which is even worse in 1.1 because each Eval must be replaced with DataBinder.Eval(Container.DataItem, "xx"). There are also occasions where you just can't compress all the logic you need to into a single expression. An alternative, which I find myself using quite a bit, even when developing in 2.0, is to write a single method in your code behind class to generate the desired string. Have it take an object reference (which will be the bound row) and take as many lines as you like to construct the string to be generated in the template. Here's a method that returns the same string as the overly-complex expression above:

Protected Function  GenerateFooString( ByVal  dataItem  As Object )  As String
    Dim  foo  As Boolean = CType (DataBinder.Eval(dataItem,  "foo" ), Boolean )
     Dim  quux  As Boolean = CType (DataBinder.Eval(dataItem,  "quux" ), Boolean )
     Dim  ret  As String = string .Empty
     If  foo  Then
         ret  = CType (DataBinder.Eval(dataItem,  "bar" ), String )
     ElseIf  quux  Then
         ret  = CType (DataBinder.Eval(dataItem,  "a" ), String )
     Else
         ret  = CType (DataBinder.Eval(dataItem,  "b" ), String )
     End If
    Return  ret
End Function

And the simplified template now looks like:

  < asp : TemplateField HeaderText ="SomeColumn">
  < ItemTemplate >
    <% # GenerateFooString(Container.DataItem) %>
  </ ItemTemplate >
</ asp : TemplateField >

Once again, this is not my code or idea; it all belongs to Fritz Onion!

I haven’t quite figured-out what this plugin does, but it sounds like something I should use since I’m trying to work with standards compliant CSS files in my latest web apps:

CSS Properties Window Plugin

I like adding help messages to web forms, but I find that these help messages can often make the page very long.  Since a user won’t like need a help message once he has read it, it’s nice to be able to hide the message.

With that in-mind, the JavaScripts below are nice samples of scripts that will display or hide content that is within a specified <DIV> tag.  They can be called from a single button or hyperlink:

function toggleDiv(divName) {
    thisDiv = document.getElementById(divName);
    if (thisDiv) {
        if (thisDiv.style.display == "none") {
            thisDiv.style.display = "block";
        }
        else {
            thisDiv.style.display = "none";
        }
    }
    else {
        alert("Error: Could not locate div with id: " + divName);
    }
}

function toggleDiv(divName) {
    var thisDiv = document.getElementById(divName);
    if (thisDiv) thisDiv.style.display = !thisDiv.offsetWidth ? "block" :"none";
    else alert("Error: Could not locate div with id: " + divName);
}

I recently took on the project of trying to create my own Business Logic Layer (BLL) and Data Access Layer (DAL) in a personal web project so I could understand how the various layers of n-tier architecture are supposed to work.  I didn’t get very far before I realized that allowing NULL database values (System.DBNull.Value) in various fields in my database was going to give me a large headache :'(

After doing a lot of research, I didn’t come-up with too many satisfactory methods for dealing with DBNulls.  At best, it seemed like I’d have to write all sorts of methods for converting DBNulls to either a default value for each data type (I.e., define an integer to default to zero, a string defaults to String.Empty, a date defaults to DateTime.MinValue, etc.) or use the new VB.NET 2.0 Nullable Types and set each data type to Nothing.  This sounded like a lot of work and a lot of code… more code = more errors!

I read a few articles on using Generic Types in VB.NET 2.0 and it appeared to me as though they could be the answer to my prayers:  Create one generic method that can check for DBNulls for all data types.  A blog post by Saravana Kumar shows a way to accomplish this using C#. However, C# has a keyword defaultwhich doesn’t exist in VB.NET (at least not that I could find.)  This keyword apparently returns the default value for each data type, just like I wanted!

After much tinkering, here is what I came-up after trying to convert Saravana’s code to VB.NET:

Public Shared Function ConvertDBNull(Of T)(ByVal obj AsObject) As T
    If (obj Is System.DBNull.Value) Then
        obj = Nothing
    EndIf
    ReturnCType(obj, T)
End Function

So far, it seems to work!  For example, with the following code:

Dim oSomeTestObject AsObject = System.DBNull.Value
Dim strResult AsString = ConvertDBNull(OfInteger)(oSomeTestObject)

The value of strResult is returned as a zero.  Another example:

Dim oSomeTestObject AsObject = System.DBNull.Value
Dim strResult AsString = ConvertDBNull(OfDate)(oSomeTestObject)

The value of strResult is returned as a “12:00:00 AM”. For most dates that I display, I always format them as MM/dd/yyyy, so a date value only exposing time won't show.

I tested this new method on my BLL, and so far it works great! w00t! If you have a better method for dealing with DBNulls in your Business Logic, let me know… I’m all ears!

I’m going to have to make reading Scott Guthrie’s blog part of my daily ritual because nearly every post is packed with useful information!  This article shows how to run a web application on your development PC as though it was running at the top-level (or “root”) web site, even if it’s configured to run in a virtual root:

How to Run a Root “/” Site with the VS/VWD 2005 Local Web Server

Why is this cool?  If you haven’t already figured it out, here’s my lame explanation:

When you configure a web site on a Windows 2003 Server using IIS 6, each site has its own root directory because IIS 6 on a web server allows for the creation of multiple web sites.  However, on a development machine running Windows XP Pro and IIS 5, you can only have one web site defined which means all other sites must be contained in virtual root folders below the main site.   The problem that this creates is that it becomes difficult to reference file paths to static files and folders.

For example, if your site contains an “images” folder and a “templates” folder (which contains your .ASCX user controls), you will likely want to reference images from within one of your user controls.  On a web server, you could reference an image path like this:

< img src =”/images/someimage.gif” alt ="My Alt Tag" />

However, that won’t work on a development PC running IIS 5 with a site defined as a virtual root.  The path would then have to be:

< img src =”/myvirtualroot/images/someimage.gif” alt ="My Alt Tag" />

Starting to see the problem here?  In the second example, all your images will break when you copy your files from your development PC to the live web server.   Using the “../” method to navigate to images used to work:

< img src =”../images/someimage.gif” alt ="My Alt Tag" />

However, do to naughty people trying to run scripts through the address bar in the browser, IIS often won’t allow for the “../” notation.  One solution is to use the method ResolveURL along with the “~/” prefix:

< img src =" <%# Control.ResolveUrl(“~/images/someimage.gif”) %>"alt="My Alt Tag"/>

But that’s just plain ugly code!   Utilizing Scott’s trick, you can reference your file paths as though you were working on a live web server without having to do any ugly work-around. Schweet!

The .NET 2.0 Framework supports a new string method for VB that should prove to be useful:

returnValue =

String .IsNullOrEmpty(value)

IsNullOrEmpty is a convenience method that enables you to simultaneously test whether a String is a null reference (Nothing in Visual Basic) or its value is Empty.

 

Who says that developers are boring and weird?  Well, they are weird, but sometimes they can be fun:

http://www.microsoft.com/korea/events/ready2005/vs_song.asp

I’m not sure if I think the video is funny because of the content or because of the Korean language that I don’t understand!

The lyrics are very good too when translated into English... they seem to relate to my job pretty well!

When using a GridView in ASP.NET 2.0, note that you must set HtmlEncode = False in addition to setting the DataFormatString or else the formatting will not work:

1. Open the Access database you wish to up-size.

 

2. Select Tools > Database Utilities > Upsizing Wizard

3. Select Create new database and then Next >

 

4. This is probably the hardest part.  The instance of your SQL Express database won’t show-up in the database dropdown list.   For the name of your SQL Server, enter MACHINENAME\SQLExpress or .\SQLExpress.  The former worked for me:



5. Make sure you name the database, click Next >, and the rest is the same as it’s always been.

The more articles I read about VisualStudio.NET 2005, the more excited I get!  This article from Scott Guthrie explains how to use the new Custom Item Template feature in VS.NET 2005 which will help eliminate the need to waste time “setting-up” a newly created page ASPX page:

Defining Custom Item Templates in Web Projects with VS 2005

A helpful MSDN article relating to the templates:

MSDN: Visual Studio Template Reference

I’m not sure if it’s a sign of getting old or just my personality type, but I like things to be organized… and that includes the files in my web projects.  Lucky for me, ASP.NET Grand-Pubba Scott Guthrie has written a nice article demonstrating ways to clean-up and organize your web projects in VisualStudio.NET 2005:

Some Techniques for Better Managing Files in Visual Studio 2005 Web Projects