ASP.NET Tutorials » Code snippets

Get the IP Address and Referer of a visitor

Vihutuo — Fri, 05 Dec 2008 06:24:11 +0000

Here is the code snippet to obtain the IP Address and Referer of a visitor to your website
Dim IPAddress=Request.ServerVariables("REMOTE_ADDR") Dim Referer=Request.ServerVariables("HTTP_REFERER")

Check a demo here

Check my IP

Replace “\n” with “”

Vihutuo — Tue, 28 Oct 2008 18:07:40 +0000

There are lot of times we accept user input in a textarea or a multiline textbox and save it to a database. But while displaying the data from the database, you will find that the line breaks are not displayed properly, infact there will be no line breaks. We will need to convert all the new line characters (“\n” character) to “
” so that they are properly rendered in the browser. There seems to be quite a few ways to do it but the simplest method which always worked for me is as follows. Just pass the string to the the function and it will format the string properly so that the new line characters are replaced with “
” tags
Public Shared Function ConvertToBR(ByVal InputString As String) As String Dim Pattern As String = "\n" Dim Rgx As New Regex(Pattern) Dim OutputString As String=Rgx.Replace(InputString, " ") Return OutputString End Function

Efficient Search Engine Friendly Gridview Paging control

Vihutuo — Thu, 16 Oct 2008 08:51:26 +0000

The Gridview Control in ASP.NET has built in paging support. But here are a few disadvantages of using the built in paging

It fetches all the records from the database even when we need only 10 records per page. This is quite inefficient when your tables have thousands of records
The paging controls uses javascript which makes the pages inaccessible to search engine.

I looked around the net for solutions to these problems. There were a few solutions and some of them even costs upwards of $100 but the best I found was a free paging control by Bidel Akbari at codeproject

Here are the main features of his paging control

Very easy to install and use.
Uses server side paging so that only the required few rows are returned from the database
Search engine friendly paging. The first version was supposed to use query strings for paging which is the way paging should work. However in the latest version 2.8 , it uses javascript for paging and a hidden div with hyperinks so that search engines can find the inner pages.
You can use the paging control with the Repeater and Datalist controls
There are a variety of properties to change the appearance of the control. He has also made two slick skins for the control

Overall a great and extremely useful control . You can see a demo of the control here in my site freedownloadablefonts.net . You can find more info and download the control here

How to access a control in the masterpage ?

Vihutuo — Mon, 25 Aug 2008 20:11:44 +0000

Suppose you have a label control name lblMessage in your masterpage and you want to access the label control from one of your pages, you can do so using the following code

Ctype( Page.Master.FindControl("lblMessage"),Label).Text = "Hello"

Insert flash file correcty in ASP.NET masterpage

Vihutuo — Mon, 25 Aug 2008 19:58:03 +0000

Many people have problems inserting flash files in masterpages . The following code is the correct way of inserting flash file in a mastepage . It will work in all situations

http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0" width="663" height="105" title="Serious Reading...."> ' pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" width="663" height="105">

Format dates in a Gridview column

Vihutuo — Mon, 25 Aug 2008 19:01:05 +0000

To format a gridview column to display dates properly , two properties needs to be changed, the DateFormatString property and the HTML encode property. After setting the DateFormatString the HTMLEncode property should be set to false. For Example :
HtmlEncode="False" SortExpression="RegistrationDate" />

Enable or disable the delete link in the GridView according to the role of the logged in user

Vihutuo — Mon, 25 Aug 2008 18:58:56 +0000

In some scenarios you may only want users of a particular role to delete records from the GridView. So you need a mechanism to disable/hide the delete link in the gridview based on roles. The code below will enable the delete link only for “Admin” roles and disable it for the rest.

Protected Sub gridView1_RowDataBound(ByVal sender As Object, ByVal e As system.Web.UI.WebControls.GridViewRowEventArgs) Handles Gridview1.RowDataBound If e.Row.RowType = DataControlRowType.DataRow Then If User.IsInRole("Admin") Then Dim DeleteLink As LinkButton = CType(e.Row.FindControl("HyperLinkDelete"), LinkButton) DeleteLink.Enabled = true else DeleteLink.Enabled = True End If End If End Sub

How do I reference a server control in javascript?

Vihutuo — Mon, 25 Aug 2008 18:47:47 +0000

<%=ServerControlID.ClientID%>

Yes that’s all you need . For Example suppose you have a asp.net textbox server control whose ID is “Textbox1″ . In your javascript code to get the value of the control you will use something like this

var myValue= document.getElementById('<%=TextBox1.ClientID%>').value;