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ASP.NET Web Forms - AJAX

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Learn ASP.NET Web Forms by building a web site from scratch.

Part V: Displaying Data Using AJAX.

What We Will Do

In this chapter we will:

Displaing data from the database using AJAX

Create an AJAX Server Page

In your web folder (DemoWebForms), create a new ASPX file named "getCustomers.aspx".

Put the following code inside the file:

getCustomers.aspx

<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.OleDb" %>

<%
Dim dbconn As OleDbConnection
Dim objAdapter As OleDbDataAdapter
Dim objTable As DataTable
Dim objRow As DataRow
Dim objDataSet As New DataSet()
dbconn=New OledbConnection("Provider=Microsoft.Jet.OLEDB.4.0;data source=C:\WebData\Northwind.mdb")
objAdapter=New OledbDataAdapter("SELECT CompanyName,City,Country FROM Customers",dbconn)
objAdapter.Fill(objDataSet,"customers")
objTable=objDataSet.Tables("customers")
objRow=objTable.Rows(0)
response.write("<table border='1'>")
response.write("<tr><th>Name</th><th>City</th><th>Country</th></tr>")
for each x in objTable.Rows
response.write("<tr>")
response.write("<td>" & x("companyname") & "</td>")
response.write("<td>" & x("city") & "</td>")
response.write("<td>" & x("country") & "</td>")
response.write("</tr>")
next
response.write("</table>")
dbconn.Close()
%>

The file above is a standard ASPX file, returning only an HTML table.

Create an AJAX Browser Page

In your "DemoWebForms" folder, create a new file named "Ajax.html".

Put the following code inside the file:

Ajax.html

<!DOCTYPE html>
<html>
<head>
<title>ASP Demo</title>
<link href="Site.css" rel="stylesheet">
</head>
<body>
<div id="main">
<h1>Customers</h1>
<div id="t01"></div>
</div>

<script>
var xmlhttp;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("t01").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getCustomers.aspx",true);
xmlhttp.send();
</script>

</body>
</html>

Try it Yourself »