The Beta1 version of WebMatrix comes with a number of Web Pages helpers to make your life simple. These include helpers to work with file uploading, images, email, caching, grids, Twitter feeds and a lot more. I suspect that as the product evolves towards full release, more will be added. Nevertheless, the developers of WebMatrix and Web Pages cannot anticipate every requirement, so there will be a time when you feel you need something extra. Adding your own helpers is quite easy, as this article shows.

One area where there is no helper currently is consuming RSS feeds. So I am going to build a helper that allows the user to display part of an RSS feed on a web page. The code that I will show here does the job, although it is far from perfect. Its purpose is to illustrate the main points involved in creating a helper, and not to be a production-ready example of how to produce an Rss reader. It lacks far too much exception handling for one thing, and I felt that adding too much would obscure the main thrust of this article. For that reason, I won't delve too deeply into the actual helper code, but I will draw attention to the key areas that should be considered when developing helpers.

The first thing to do is to add a new folder to the web site. This folder must be named "App_Code". Future versions of WebMatrix may offer this in something like an "Add New ASP.NET Folder" menu option at some stage, but that's not currently available. App_Code is a special folder. ASP.NET will compile anything inside this the first time the site is run, and it will be available to other code throughout the site. Within that folder, add a new file. The type of file is a C# class file.



Call this file "RssReader.cs", and then remove all the code that's in it, then replace it with the following:

using System;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Xml.Linq;

public static class RssReader
{
  public static HtmlString GetHtml(string url, int numberOfItems = 5,
                        bool showDescription = true, bool showDateCreated = true, int width = 300)
  {
    TagBuilder divTag = new TagBuilder("div");
    TagBuilder pTag = new TagBuilder("p");
    TagBuilder anchor = new TagBuilder("a");   

    var doc = XDocument.Load(url);
    XNamespace a10 = doc.Root.GetNamespaceOfPrefix("a10");
    var items = doc.Descendants("item").Select(feed => new
    {
      Title = feed.Element("title"),
      Link = a10 != null ? feed.Element(a10 + "link").Attribute("href").Value : feed.Element("link").Value,
      Date = feed.Element("pubDate"),
      Description = feed.Element("description")
    }).Take(numberOfItems);

    divTag.MergeAttribute("id", "rssDiv");
    divTag.MergeAttribute("style", "width:" + width + "px");
    foreach(var item in items)
    {
      anchor.InnerHtml = item.Title.Value;
      anchor.MergeAttribute("href", item.Link);
      pTag.InnerHtml = anchor.ToString();
      divTag.InnerHtml += pTag.ToString();
      if(showDateCreated)
      {
        TagBuilder pTag2 = new TagBuilder("p");
        DateTime dateValue;
        if(DateTime.TryParse(item.Date.Value, out dateValue))
        {
          pTag2.InnerHtml = dateValue.ToString("G");
        }
        divTag.InnerHtml += pTag2.ToString();
      }
      if(showDescription)
      {
        TagBuilder pTag3 = new TagBuilder("p");
        pTag3.InnerHtml = item.Description.Value;
        divTag.InnerHtml += pTag3.ToString();
      }
    }
    return new HtmlString(divTag.ToString());
  }
}

Right - before you pass out, let me explain how this code works. It's simple, really. The first 5 lines make certain namespaces available to the code so that when we reference items within them, we do not have to use their fully qualified name. You can see public static HtmlString near the beginning of the code. The fully qualified reference for HtmlString is System.Web.Mvc.HtmlString, and without adding a using statement to make System.Web.Mvc available to the class file, we would have to type the fully qualified name every time we wanted to reference HtmlString. System.Web.Mvc also makes TagBuilder available in a short-handed fashion too.

You should also note that both the RssReader class and the GetHtml method are static. This means we do not have to create an instance of RssReader in order to call the GetHtml method from a web page or other code. This is typical of helper methods, and other utility methods in general.

The parameters for the GetHtml method are worth noting too. The first one is a required parameter. In other words, when the GetHtml method is called, you must pass a string as an argument. Ideally, that string will be a valid Uri pointing the the location of an RSS feed. There's no checking in the method to make sure it is. This is one of the missing pieces of exception management I mentioned earlier. The other 4 parameters are all optional. In other words, the caller does not need to provide any values for them. You can see they are optional as they have default values. Optional parameters were added in C# 4.0, and are a terrific way to add flexibility without the need for creating multiple overloaded versions of the GetHtml method. Optional parameters must always be declared AFTER all required parameters (except for one case involving params arrays, but that's not important here).

The next thing of note is the 3 TagBuilder objects that are created. TagBuilder is a very useful class introduced with ASP.NET MVC if you ever want your helper to render html elements, along with HtmlString. TagBuilders allow you to specify an html tag such as a <p> for paragraph, or <input type="text" />, without having to fiddle around with building the string manually, which can be error prone, especially when trying to deal with embedded double quotes. HtmlString ensures that the resulting concoction of tags and html are rendered as html, rather than being html-encoded.

The RSS feed is obtained via the XDocument.Load() method, which is part of System.Xml.Linq. I'm not going to go into too much detail about Linq To XML but it is a nice way to deal with XML, which is what an RSS feed is, once you get to grips with the basics of the subject (which I hope to do one day...). Suffice to say that assuming the Load method actually managed to retrieve the XML file (again, error checking should be in place there) some items are retrieved from it and used to build a collection of objects. How many objects are built depends on the value passed in to the numberOfItems parameter. If no value was provided, it will default to 5 items.

Now that we have a collection of objects, they are iterated through to build some html. The resulting RSS feed will be housed in a div element, with a width of 300px by default. This can be customised by the user if they choose to pass a value into the method. While iterating the collection, the code builds an html link from the item's Link property, and puts that into a paragraph element. Then it checks ot see if the caller decided to include the published date in their RSS Reader. If they did, or left the default value, this is added to another paragraph element. Finally if the showDescription value is true, item descriptions are added to another paragraph, before looping to the next item in the collection. Finally, the whole lot is returned to the caller as a string of Html.

Before showing how this code can be used in a cshtml file, I will take a second to review the key points about constructing helpers:

1. App_Code is the place for class files which need to be made available across the site
2. Helper classes and methods should invariably be static
3. HtmlStrings ensure that anything to be rendered by the browser is sent as Html
4. TagBuilders make building valid Html a lot easier
5. Optional parameters save a lot of code by reducing the need to create overloaded methods

Here are a couple of ways in which the helper can be called within a Web Pages file:

@RssReader.GetHtml("http://dotnet4europeanhosting.hostforlife.eu/rss")

@RssReader.GetHtml("http://dotnet4europeanhosting.hostforlife.eu/rss/", showDescription: false, width: 400, numberOfItems: 10)

The first line makes use of all default values applied to the optional parameters, while the second one changes the number of items to 10, increases the width of the housing div, and elects not to display descriptions. It leaves the helper to show the date. You should also notice that the optional parameters arguments are prefixed by the name of the parameter, and are not added to the method call in the order in which they appear in the method parameter list itself. Named parameters was also introduced in C# 4.0, and the link to Optional parameters provided earlier explains more about this too.

Here, we'll see how to implement a Twitter like multiline asp:TextBox character counter that counts how many characters are entered in the asp:TextBox using simple javascript. We'll also restrict user to post (submit) Text, if the entered character count is greater than Max. allowed characters by disabling the Button.

Let's start by creating a new ASP.Net website named 'TwitterLikeTextCounter', say. In the 'Default.aspx', insert three controls i.e. a multiline asp:TextBox (used to enter character input), a readonly asp:TextBox (used to show the character count) and a button. As we want to impose some Max. allowed characters restriction on the Multiline asp:TextBox, if the character count in asp:TextBox exceeds the maximum allowed characters then the submit button is disabled and the character counter CSS is also changed. Add the below code in head section of page:

<script language="javascript" type="text/javascript">
  function GetButtonTwitterLikeCounter() {
    return document.getElementById('<%= btnTwitterLikeCounter.ClientID %>');
  }
  function GetTextBoxCharacterCounter() {
    return document.getElementById('<%= TextBoxCharacterCounter.ClientID %>');
  }
  function SetTextBoxCharacterCounter(src) {
    txtCount = GetTextBoxCharacterCounter();
    txtCount.value = 100 - src.value.length;
  }
  function checkLength(src, len) {
    txtCount = GetTextBoxCharacterCounter();
    txtCount.value = len - src.value.length;

    try {
      if (src.value.length > (len)) {
        if (txtCount.value < 0) {
          txtCount.className = "WarningTwitterLikeCounter";
          GetButtonTwitterLikeCounter().disabled = true;
        }

        return false;
      }
    } catch (e) { }

    txtCount.className = "NormalTwitterLikeCounter";
    GetButtonTwitterLikeCounter().disabled = false;
  }
</script>

The page markup code would be as below:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
  <title>ASP.Net & Javascript: Twitter like Multiline TextBox Counter</title>
  <style type="text/css">
    .NormalTwitterLikeCounter
    {
      border-color: White;
      border-style: none;
      font-family: Arial;
      color: #FF9900;
      background-color: #FFFFFF;
    }
    .WarningTwitterLikeCounter
    {
      border-color: White;
      border-style: none;
      font-family: Arial;
      color: Red;
      background-color: #FFFFFF;
    }
  </style>
</head>
<body>
  <form id="form1" runat="server">
    <asp:TextBox ID="TwitterLikeTextBox" runat="server" Columns="20" Rows="5" TextMode="MultiLine" onblur="SetTextBoxCharacterCounter(this)" onkeyup="return checkLength(this,100)">
    </asp:TextBox>
    <asp:TextBox ID="TextBoxCharacterCounter" runat="server" ReadOnly="True" Width="35px" CssClass="NormalTwitterLikeCounter">100
    </asp:TextBox>
    <asp:Button ID="btnTwitterLikeCounter" runat="server" Text="Twitter Like TextBox Character Counter" />
  </form>
</body>
</body>

The code for the 'ASP.Net & Javascript: Twitter like Multiline TextBox Counter' is pretty self explainatory and ofcourse you can modify the code for 'ASP.Net & Javascript: Twitter like Multiline TextBox Counter' according to your needs.

That's all, I hope you have got an idea of how to make a Twitter like Multiline TextBox Counter using Asp.Net & Javascript.

This brief article demonstrates the simplest way and step by step instructions on how to send email from aspx page using a gmail account. After reading this you'll be able to send HTML formatted email messages by using Asp.Net and C#.

In order to send an email from gmail account programmatically, you have to include the following namespace:

using System.Net.Mail; // contains classes for SMTP settings, email sending etc

Let's take a look at the soure of aspx page. It has only three fields and a button to send email

<form id="form1" runat="server">
    <asp:Label ID="lblEmailAddress" runat="server" Text="Email Address:"></asp:Label>
    <asp:TextBox ID="txtEmailAddress" runat="server" Width="300px"></asp:TextBox>
    <br />
    <asp:Label ID="lblEmailSubject" runat="server" Text="Subject of Email:"></asp:Label>
    <asp:TextBox ID="txtEmailSubject" runat="server" Width="300px"></asp:TextBox>
    <br />
    <asp:Label ID="lblEmailMessageBody" runat="server" Text="Email Message Body:"></asp:Label>
    <asp:TextBox ID="txtEmailMessageBody" runat="server" Rows="5" TextMode="MultiLine"
        Width="300px"></asp:TextBox>
    <br />
    <asp:Button ID="btnSendEmail" runat="server" OnClick="btnSendEmail_Click" Text="Send Email" />
    <asp:Label ID="lblEmailStatus" runat="server"></asp:Label>
</form>

Email Address: the address to which the email is to be sent
Subject of Email: The subject line of email and
Email Message Body: As we want to send HTML instead of simple plain text so whatever is placed in this field, will be formatted using html styles.

Pretty simple ... ok let's move to server side code:

protected void btnSendEmail_Click(object sender, EventArgs e)
{
    lblEmailStatus.Text = "";
    if (SendEmails())
        lblEmailStatus.Text = "Your Email has been sent";
    else
        lblEmailStatus.Text = "Error: Sending Email";
}

This is the event handler of Send Email button. It simply calls SendEmails() function and sets the status of label whether the email is sent successfully or not. Now lets look at SendEmail function:

private bool SendEmails()
{
    try
    {
        MailMessage mail = new MailMessage();
        mail.To.Add(txtEmailAddress.Text);
        mail.From = new MailAddress("[email protected]");
        mail.Subject = "Sending Email from aspx: " + this.txtEmailSubject.Text;
        string Body = "<div style='font-family:Comic Sans MS; color:Navy; font-size:small'>" +
        "<br/>" +
        "<b>Email Date and Time:</b> " + DateTime.Now.ToString() + "" +
        "<br/>" +
        "<br/>" +
        "See the Following Email Message:" +
        "<br/>" +
        "<br/>" +
        "<b>" + this.txtEmailMessageBody.Text + "</b>" +
        "<br/>" +
        "<hr/>" +
        "</div>";
        mail.Body = Body;
        mail.IsBodyHtml = true;

        SmtpClient smtp = new SmtpClient();
        smtp.Host = "smtp.gmail.com";
        smtp.Port = 587;
        smtp.UseDefaultCredentials = false;
        smtp.Credentials = new System.Net.NetworkCredential("[email protected]", "email password");
        smtp.EnableSsl = true;
        smtp.Send(mail);

        return true;
    }
    catch (Exception)
    {
        return false;
    }
}

First we will build the actual email message i.e. MailMessage, then configure the SmtpClient and send the email using that SmtpClient. One important thing: Gmail is using 587 of the host smtp.gmail.com

Rest the code is pretty simple and neat ... let me know if you have any questions regarding Sending email.

Another same tutorial, How to Send Email Using Gmail in ASP.NET

In this article I am explaining how to upload multiple files by dynamically adding FileUpload controls using JavaScript.

Here I will explain how one can create a multiple file uploading controls in a very simple manner and very less amount of code. With this example one will able to perform the following functions

1. Add FileUpload Controls dynamically using JavaScript

2. Remove FileUpload Controls dynamically using JavaScript.

Since I am using JavaScript the UI becomes elegant since no need of postback or AJAX to add or remove FileUpload Controls.

Adding and Removing FileUpload Controls using JavaScript

Below is the HTML markup of the page. As you can see I have added a HTML button in order to add new FileUpload Controls, a DIV FileUploadContainer in which the dynamic FileUpload Controls will be added and a ASP.Net Upload Button in order to upload the files when the Upload Button us clicked.

An important think to note that you will need to add enctype="multipart/form-data to the form in order to allow the uploading of files through dynamic FileUpload controls.

<form id="form1" runat="server" enctype="multipart/form-data" method = "post">
    <span style ="font-family:Arial">Click to add files</span>&nbsp;&nbsp;
    <input id="Button1" type="button" value="add" onclick = "AddFileUpload()" />
    <br /><br />
    <div id = "FileUploadContainer">
        <!--FileUpload Controls will be added here -->
    </div>
    <br />
    <asp:Button ID="btnUpload" runat="server"
      Text="Upload" OnClick="btnUpload_Click" />
</form>

Now in order to add and remove the FileUpload Controls dynamically here is the JavaScript functions that are used.

<script type = "text/javascript">
var counter = 0;
function AddFileUpload()
{
     var div = document.createElement('DIV');
     div.innerHTML = '<input id="file' + counter + '" name = "file' + counter +
                     '" type="file" />' +
                     '<input id="Button' + counter + '" type="button" ' +
                     'value="Remove" onclick = "RemoveFileUpload(this)" />';
     document.getElementById("FileUploadContainer").appendChild(div);
     counter++;
}
function RemoveFileUpload(div)
{    
document.getElementById("FileUploadContainer").removeChild(div.parentNode);
}
</script>

As you will notice above first I am creating a DIV element and then adding a HTML FileUpload Control along with a HTML Button in order to remove the FileUpload Controls. Also onclick of the Remove button I am calling the RemoveFileUpload function which removes the dynamically created FileUpload control. 

Server Side Uploading of Files

Server Side I have written the following code in the Click event of the Upload Button

C#

protected void btnUpload_Click(object sender, EventArgs e)
{
    for (int i = 0; i < Request.Files.Count; i++)
    {
        HttpPostedFile PostedFile = Request.Files[i];
        if (PostedFile.ContentLength > 0)
        {
            string FileName = System.IO.Path.GetFileName(PostedFile.FileName);
            PostedFile.SaveAs(Server.MapPath("Files\\") + FileName);
        }
    }
}

VB.Net

Protected Sub btnUpload_Click(ByVal sender As Object, ByVal e As System.EventArgs)
  For i As Integer = 0 To Request.Files.Count – 1
   Dim PostedFile As HttpPostedFile = Request.Files(i)
   If PostedFile.ContentLength > 0 Then
      Dim FileName As String = System.IO.Path.GetFileName(PostedFile.FileName)
      PostedFile.SaveAs(Server.MapPath("Files\") + FileName)
   End If
  Next
End Sub 

In the above code snippet I am simply looping through the Request.Files Collection which contains the uploaded Files and then I am saving each of them one by one in a Folder called Files within my website root folder. 

Web.Config Configurations

Since this article deals with uploading multiple files it is important to discuss the maximum file size allowed. By default ASP.Net allows files of size maximum 4MB at a time. Hence in order to upload more data we will need to increase this limit. Refer the httpRuntime section of the Web.Config, if it is not present in your Web.Config you can simply paste the one given below in your file.

<httpRuntime
  executionTimeout="110"
  maxRequestLength="4096"
  requestLengthDiskThreshold="80"
  useFullyQualifiedRedirectUrl="false"
  minFreeThreads="8"
  minLocalRequestFreeThreads="4"
  appRequestQueueLimit="5000"
  enableKernelOutputCache="true"
  enableVersionHeader="true"
  requireRootedSaveAsPath="true"
  enable="true"
  shutdownTimeout="90"
  delayNotificationTimeout="5"
  waitChangeNotification="0"
  maxWaitChangeNotification="0"
  enableHeaderChecking="true"
  sendCacheControlHeader="true"
  apartmentThreading="false"
/>

In order to increase the maximum file size limit you will need to change the value of the maxRequestLength attribute in kilobytes (KB). For example if you want to set the upload limit to 10 MB you will have to set the value to 10240. Another important parameter is executionTimeout. It determines the maximum amount of time in seconds ASP.Net will process the request and after which it will stop the processing. By default the value is 110 seconds. You can modify it to the value that suits your needs



The above code has been tested in the following browsers

A typical web.config file in v2.0 could have the following section which is placed directly under the root <configuration> section.

<connectionStrings>
    <remove name="LocalSqlServer" />
    <add name="LocalSqlServer" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
    <add name="MainConnStr" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|main.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
</connectionStrings>

connectionStrings>
    <remove name="LocalSqlServer" />
    <add name="LocalSqlServer" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
    <add name="MainConnStr" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|main.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
</connectionStrings>

You can reference this directly from code using:

[C#]
string connStr = ConfigurationManager.ConnectionStrings["MainConnStr"].ConnectionString;

[VB]
Dim connStr As String = ConfigurationManager.ConnectionStrings("MainConnStr").ConnectionString

Note that the namespace for this is System.Configuration so for a console application the full namespace is required.

Or you can reference this declaratively within the ConnectionString property of a SqlDataSource:

<asp:SqlDataSource ID="SqlDataSource1" runat="server"
  ConnectionString="<%$ ConnectionStrings:MainConnStr %>"
  SelectCommand="SELECT [au_id], [au_lname], [au_fname], [state] FROM [authors]" />

If you want to send email using your Gmail account or using Gmail's smtp server in ASP.NET application or if you don't have a working smtp server to send mails using your ASP.NET application or aspx page than sending e-mail using Gmail is best option.

You need to write code like this

First of all add below mentioned namespace in code behind of aspx page from which you want to send the mail.

using System.Net.Mail;

Now write this code in click event of button

C# code

protected void Button1_Click(object sender, EventArgs e)
{
  MailMessage mail = new MailMessage();
  mail.To.Add("[email protected]");
  mail.To.Add("[email protected]");
  mail.From = new MailAddress("[email protected]");
  mail.Subject = "Email using Gmail";

  string Body = "Hi, this mail is to test sending mail"+
                "using Gmail in ASP.NET";
  mail.Body = Body;

  mail.IsBodyHtml = true;
  SmtpClient smtp = new SmtpClient();
  smtp.Host = "smtp.gmail.com"; //Or Your SMTP Server Address
  smtp.Credentials = new System.Net.NetworkCredential
       ("[email protected]","YourGmailPassword");
//Or your Smtp Email ID and Password
  smtp.EnableSsl = true;
  smtp.Send(mail);
}

VB.NET code

Imports System.Net.Mail

Protected  Sub Button1_Click
(ByVal sender As Object, ByVal e As EventArgs)
  Dim mail As MailMessage =  New MailMessage()
  mail.To.Add("[email protected]")
  mail.To.Add("[email protected]")
  mail.From = New MailAddress("[email protected]")
  mail.Subject = "Email using Gmail"

  String Body = "Hi, this mail is to test sending mail"+
                "using Gmail in ASP.NET"
  mail.Body = Body

  mail.IsBodyHtml = True
  Dim smtp As SmtpClient =  New SmtpClient()
  smtp.Host = "smtp.gmail.com" //Or Your SMTP Server Address
  smtp.Credentials = New System.Net.NetworkCredential
       ("[email protected]","YourGmailPassword")
  smtp.EnableSsl = True
  smtp.Send(mail)
End Sub

You also need to enable POP by going to settings > Forwarding and POP in your gmail account

Change [email protected] to your gmail ID and YourGmailPassword to Your password for Gmail account and test the code.

If your are getting error mentioned below
"The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required."

than you need to check your Gmail username and password.

If you are behind proxy Server then you need to write below mentioned code in your web.config file

<system.net>
<defaultProxy>
<proxy proxyaddress="YourProxyIpAddress"/>
</defaultProxy>
</system.net>

If you are still having problems them try changing port number to 587

smtp.Host = "smtp.gmail.com,587";

If you still having problems then try changing code as mentioned below

SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.gmail.com";
smtp.Port = 587;
smtp.UseDefaultCredentials = False;
smtp.Credentials = new System.Net.NetworkCredential
("[email protected]","YourGmailPassword");
smtp.EnableSsl = true;
smtp.Send(mail);

Hope this help!!

Introduction

When Microsoft released its flavour of AJAX framework named "ASP.NET AJAX" as part of ASP.NET 3.0 preview, it did not have much competency when compared to other AJAX frameworks. But when I evaluated ASP.NET AJAX 4.0, I was really inspired with the new features that are completely focused on your browser technologies such as XHTML and JavaScript. I really admired the effort made by the ASP.NET AJAX team. There could not be any second opinion when you see the following features:

- Template based client side programming
- DataView and DataContext
- Live Data Binding

Template Programming

Template provides pattern to design a web UI form and enables to put placeholders for runtime data. For example, I've designed a web page to display AdventureWorks database Product data through ADO.NET data service. The entity model (edmx) is:



The service code is:

public class AWProductDataService : DataService
{  
    public static void InitializeService(IDataServiceConfiguration config)
    {
        config.SetEntitySetAccessRule("*", EntitySetRights.All);
    }
}

By ASP.NET templates, the page looks like:

<%@ Page Language="C#" AutoEventWireup="true"
  CodeBehind="ClientTemplateAndDataViewDemo.aspx.cs"
  Inherits="CoreEnhancements.AJAX.ClientTemplateAndDataViewDemo" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Microsoft Tech.Ed - Client-side Templating Demo</title>
    <style type="text/css">
        .sys-template {display:none}
    </style>    
    <script type="text/javascript" src="../scripts/MicrosoftAjax.debug.js"></script>
    <script type="text/javascript" src="../scripts/MicrosoftAjaxTemplates.debug.js">
    </script>
    <script type="text/javascript" src="../scripts/MicrosoftAjaxAdoNet.debug.js">
    </script>
    <script type="text/javascript">
        var dataContext = new Sys.Data.AdoNetDataContext();
        dataContext.set_serviceUri("AWProductDataService.svc");
        dataContext.initialize();
    </script>
</head>
<body xmlns:sys="javascript:Sys" xmlns:dataview="javascript:Sys.UI.DataView"
  sys:activate="*">
    <form id="form1" runat="server">   
    <div> 
    <table border="1">
        <thead>
            <tr>
                <td>Name</td>
                <td>List Price</td>
                <td>Size</td>
                <td>Weight</td>
            </tr>
        </thead>   
    <tbody class="sys-template" sys:attach="dataview" dataview:autofetch="true"
    dataview:dataprovider="{{ dataContext }}"
    dataview:fetchoperation="Products">                
        <tr>
          <td>{binding Name }</td>
          <td>{binding ListPrice}</td>
          <td>{binding Size}</td>
          <td>{binding Weight}</td>
        </tr>
    </tbody>
    </table>
    </div> 
    </form>
</body>

I have used a typical HTML table for displaying the data. You can see some new attributes in <TBODY> and data place holders in <TD>. ASP.NET AJAX 4.0 has a dedicated template engine to parse these new attributes and data place holders. ASP.NET AJAX has defined a rich set of attributes and data placeholder patterns collectively called as expression language which are none other than X(HT)ML and JavaScript. Remarkable point here is its XHTML compliance, so these are not custom attributes in the regular HTML elements. The class attribute of the <TBODY> is set to sys-template, which is a convention used to hide the initial template from the user. .sys-template {display:none} The fields or properties of a data item which are needed to be rendered on data place holders can be expressed by {{ }} or { }.

DataContext

Template requires data for its place holders as contexts. The data context enables to bind any JavaScript array or objects to template. The real power of data context is to interact with JSON/ATOM based web services. ASP.NET AJAX provides two data contexts in MicrosoftAjaxAdoNet.js:

- Sys.Data.DataContext
- Sys.Data.AdoNetDataContext

The data context tracks all changes to the data automatically using new Sys.Observer object. AdoNetDataContext supports additional features for ADO.NET data services such as identity management, links and association between entity sets. The below code sample describes how to interact with AdventureWorks Product's ADO.NET data service:

var dataContext = new Sys.Data.AdoNetDataContext();
dataContext.set_serviceUri("AWProductDataService.svc");
dataContext.initialize();

The set_serviceUri() method is used to interact with WCF AJAX or ADO.NET data service. The initialize() method does initialization or invocation.

Data View

This is the fundamental component for templates to display data defined in System.UI.DataView. This is similar to server side data source component supports to bind any JavaScript object or array or to any ASP.NET AJAX component. It has two properties to bind a data set:

- data - To bind a JavaScript array or object
- dataprovider - To bind to a WCF service

The fetchoperation property is used to set which method needs to be invoked for fetching data. In the code snippet 1, I've set the dataContext declared in code snippet 2 as data source. To run this application, refer to the following ASP.NET AJAX client side libraries:

- MicrosoftAjax.js
- MicrosoftAjaxTemplates
- MicrosoftAjaxAdoNet

The xmlns:sys declares the namespace Sys for the entire page (Code 1. Line 2). The xmlns:dataview declares DataView control. A data view instance has been associated with <TBODY> using sys:attach.

The following figure shows the conceptual model of the template programming:



The output code is: