Here I will record the steps I took to get the fantastic SubSonic Starter Kit up and running on my PC.

1. Install ASP.NET AJAX on your machine.
2. Create a new web site in Visual Studio 2005
3. Download the latest version of the SubSonic Starter Kit
4. Copy the contents of the archive to the root directory of the web site you created in step 2
5. Select Build > Rebuild Website from the menu
6. Hit F5

That’s it. Piece of cake.

The two methods below recursively search for a control within a control. The first searches for a Textbox and the second searches for a DropDownList. The methods also accept the position of the control, e.g. 0 for the first TextBox, 1 for the second Textbox. I was using these methods to find controls within a WizardStep before I discovered generics (see below for better, more generic solution).

private TextBox FindTextBox(Control c, int positionOfControl)

{

   _positionOfControl = positionOfControl;
   if (c == null) return null;

   if (typeof(TextBox) == c.GetType())

   {
      if (_positionOfControl == 0)

      {

         return c as TextBox;

      }

      else

      {

         _positionOfControl--;

      }

   }

   Control results;

   foreach (Control child in c.Controls)

   {

      results = FindTextBox(child, _positionOfControl);

      if (results != null && typeof(TextBox) == results.GetType())

      {

         return results as TextBox;

      }

   }

   return null;}

and

private DropDownList FindDropDownList(Control c, int positionOfControl)

{

   _positionOfControl = positionOfControl;

   if (c == null) return null;

   if (typeof(DropDownList) == c.GetType())

   {

      if (_positionOfControl == 0)

      {

         return c as DropDownList;

      }

      else

      {

         _positionOfControl--;

      }

   }

   Control results;

   foreach (Control child in c.Controls)

   {

      results = FindDropDownList(child, _positionOfControl);

      if (results != null && typeof(DropDownList) == results.GetType())

      {

         return results as DropDownList;

      }

   }

   return null;}

To find the first TextBox in a WizardStep I’d write the following code:

TextBox textbox = FindTextBox(Wizard1.WizardStep[1], 0);

This works fine but leads to code bloat if you need to search for different type of controls. Enter Generics.

Generics Solution

It’s all in the name and the code below demonstrates a perfect use for generics. The code is verbose enough to not require explaination.

private T FindControl<Control>(Control c, int positionOfControl) Where T:Control

{

   _positionOfControl = positionOfControl;

   if (c == null) return null;

   if (typeof(T) == c.GetType())

   {

      if (_positionOfControl == 0)

      {

         return c as T;

      }

      else

      {

         _positionOfControl--;

      }

   }
   

   Control results;

   foreach (Control child in c.Controls)

   {

      results = FindControl(child, _positionOfControl);

      if (results != null && typeof(T) == results.GetType())

      {

         return results as T;

      }

   }

   return null;}

To use this method just code:

Textbox textBox = FindControl<TextBox>(Wizard1.WizardStep[1],0)

or

DropDownList dropDownList = FindControl<DropDownList>(Wizard1.WizardStep[1], 0)

Tags: generics, c#, asp.net

Out of the box, DataGrid and GridView provides paging support. I’d advise against using free paging because its inefficient. When switching between pages, the control queries the database for the entire resultset. If your table is only likely to have 100 or so rows in it, then fine. Otherwise, use the much more efficient method of paging at the database level, only retrieving the records you need for a single page of results.

A side benefit of rolling your own paging control is that it will work with JavaScript switched off. Hooray! Remove those nasty anchors that have their href set to call a JavaScript function, e.g. <a href="javascript:###">. Now the page links are accessible to all, including search engines, and can be bookmarked. Hooray again!

One approach to formatting a date in DataList, DataGrid, Repeater, Gridview, etc… is to cast the object to a DateTime object and use its ToString method:

<%# ((DateTime)DataBinder.Eval(Container.DataItem, "StartDate")).ToString("dd-MMM-yyyy") %>

Genius.

If you wanting to move a Visual Studio 2003 project to Team Foundation server then Dave can help you out.

An approach moving VS2003/VSS projects to Team Foundation Server

In the last post I discovered the Strongly Typed DataSet. There’s little reason to not using typed DataSets because Visual Studio will generate the necessary code for you and it only takes a moment. Yes, really. The DataSet wizard will create SQL statements or stored procedures or use existing stored procedures. Writing the Data Access Layer (DAL) of your application has never been such a painless task!

TableAdapter – the fifth class

When you create a DataSet using Visual Studio 2005 it will create 5 classes. For example, say you point to the Customer table of your database (named StoreDB), you will end up with:

• StoreDBDataSet
• CustomerDataTable
• CustomerDataRow
• CustomerRowChangeEvent
• CustomerTableAdapter

The four classes, i.e. each of the classes above except for the DataSet class, are repeated for each table defined in the DataSet.

The TableAdapter is the strongly-typed equivalent of the standard DataAdapter. Nice eh? I’m only just getting my head around this and it is making sense, slowly.

Here’s a quote from an article by Brian Noyes that succintly describes what a TableAdapter’s purpose is:

Finally, and perhaps most importantly, when you create typed data sets in Visual Studio 2005 from a database, you also get a table adapter type created for each table that you add to the data set. A table adapter is a full fledged data access component that lets you retrieve and update data from the database. It encapsulates a connection, a data adapter, and a set of command objects that allow you to execute queries to the database. I’ll get into more detail on table adapters in a little bit.

Further Reading

Jackie Goldstein has a good tutorial on the TableAdapter. It took me a couple of reads to understand what benefits the TableAdapter brings and how it saves me from writing lots of code, which is always worth the effort.

Update: Listen to Jackie Goldstein speak about the TableAdapter on DotNetRocks podcast. Skip to 44 minute 40 seconds in the audio file to get straight to the subject at hand.

In my quest to learn ASP.NET I have stumbled across the DataSet object.

A DataSet is an in-memory cache of tables, obtained from a relational database or an XML document.

Unfortunately, IntelliSense does not work well with DataSet objects. You must remember the database table and column names. For example, working with untyped DataSet you would write:

string firstName = dS.Tables["Customers"].Rows[0]["FirstName"].ToString();

As well as remembering column names, you have to use methods such as ToString() to get the correct data type out.

This is where Strongly Typed DataSets come to the rescue. The line of code above can be rewritten when using a Strongly Typed DataSet:

string firstName = dS.Customers[0].FirstName;

Witness, there’s no conversion from one type to another and IntelliSense works. These two benefits alone are worth the trouble of using Strongly Typed DataSets because it will drastically reduce the number of typing errors one makes.

Further Reading

I thoroughly recommend reading Efficient Coding With Strongly Typed DataSets to get to grips with the benefits of using Strongly Typed DataSet objects.

Today I’m learning about server controls. What, why and how? There’s two types, HTML Server Controls and Web Server Controls. Both types must be wrapped by a single <form runat="server"> tag.

Intrinsic HTML Server Controls

Intrinsic server controls are standard HTML tags containing a runat="server" attribute. For example:

<input type="text" id="name" runat="server" />

This creates an HtmlInputText server control and is accessible in your code using name.Value.

Web Server Controls

ASP.NET offers a rich set of custom controls that generate HTML content for you. Instead of the above HTML <input> element, the equivalent control is:

<asp:TextBox id="name" runat="server" />

The web server controls come with a lot more power though. For example, we can customise the TextBox control:

<asp:TextBox id="name" runat="server" TextMode="Password" Columns="40" />

In this case, the TextMode property is set so it hides the text entered into the text field. The Columns property sets the size attribute of the HTML input tag that ASP.NET generates.

More Advanced Controls

Microsoft have a small tutorial on each web server control ASP.NET offers. Included are list controls – DropDownList, ListBox and RadioButtonList – and more advanced controls such as Calendar and Wizard.

Over the past year I’ve been developing with a text browser. I manually typed XHTML, CSS and JavaScript code, observing best practices promoted by the web standards community. I wrote the server side code in a text editor too.

Teaching myself ASP.NET is making me wince. I thought outputting invalid non-semantic HTML was a bad enough crime. I am shocked and appalled to discover the bloated JavaScript code ASP.NET generates to check that a text box is not empty. The code below generates 23.8KB of JavaScript, all because of the RequiredFieldValidation control. The HTML document too has splashes of JavaScript code throughout the page.

<form id="form1" runat="server">
<div>
<p>
Username:<br />
<asp:TextBox ID="usernameTextBox" runat="server" />
<asp:RequiredFieldValidator ID="usernameReq" runat="server" ControlToValidate="usernameTextBox" ErrorMessage="Username is required!" SetFocusOnError="True" />
</p>
<p>
<asp:Button ID="submitButton" runat="server" Text="Submit" />
</p>
</div>
</form>

Remove the RequiredFieldValidation control and all traces of JavaScript disappear.

Why so much JavaScript code?

The JavaScript code generated is for every validator control in ASP.NET. Still, 23.8KB is a hefty download, even if it covers all validation controls. Why haven’t the Microsoft .NET development team at least compressed the JavaScript?

I’ve verified that the generated JavaScript files have the same across different web pages, which means the browser does not have to download the files on each new page load.

The alternative

In order to avoid bulky JavaScript code, there are two options.

Use HTML controls and write your own validation code. The downside is that you will also have to write server-side validation code in case JavaScript has been switched off in the browser.

Spin your own CustomValidator. You can use the ServerValidate event to handle serve-side validation and set the ClientValidationFunction property to the name of the client-side JavaScript validation function.

I’m a .NET newbie. I’m learning the basics from a book that is really a lengthy ASP.NET tutorial. So far, so good.

Putting my web developer’s hat on, I am disappointed by the mark-up produced by .NET controls. It doesn’t validate. Take the following code:

<form runat="server">
<asp:Button id="button" runat="server" OnClick="button_Click" Text="Click Me" />
<asp:Label id="messageLabel" runat="server" />
</form>

It produces the following mark-up:


<form name="ctl00" method="post" action="ClickEvent.aspx" id="ctl00">
<div>
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwULLTE4Nzk4Mzk1MzRkZAYY+czHhSGkOW9gO8GqxURPVBeZ" />
</div>
<input type="submit" name="button" value="Click Me" id="button" />
<span id="messageLabel"></span>
<div>
<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="/wEWAgLVuv2KBwLz9r7ABPTBiD6bHah0G6B4fEICXl+rcO/V" />
</div></form>

There are a number of issues:

• The form tag’s name attribute is deprecated in XHTML.
• The ViewState value is encryped in a hidden input tag, which is wrapped in a DIV in order to make it validate. This extra HTML is plain nasty. It goes against what web standards promotes, i.e. clean, semantic mark-up.

Possible Solutions

“Intercept the HTML code before it is sent to the web browser” – The Code Project, Sep 2004.

I’m sure there’s a few more ways of getting ASP.NET to generate HTML but as I am humble beginner I’ll stop looking for now and post update when I’ve found them.