ASP.NET Validation Controls: How to Disable It

Validating an input is a common need, sometimes we want a field must be filled, a field must be in a specific range, or an input must follow a special pattern. ASP.NET has a bunch of validation controls that make our job a little bit easy. Despite all of the ease of use offered by ASP.NET validation controls, sometimes -just maybe- we need to disable it.

One important thing we must if we use ASP.NET validation controls is: what actions will trigger validators? One of the answer is button click! (The other maybe Postback action). With that in mind, we can take a conclusion that every click event of asp.net button (<asp:Button />) by default will always trigger validation controls to take the appropriate action.

Let’s say I want to disable RequiredFieldValidator against a TextBox control for one action, and enable it for another action, how can I accomplish this? Consider I have textbox control and two button controls (previous button and next button accordingly). I want if previous button clicked it goes to previous page and doesn’t fire the required field validator. Well, the solution is really simple.

Error “‘Sys’ is undefined” in Asp.Net Ajax

When I try ASP.NET Ajax in my development server I get this Javascript error: “‘Sys’ is undefined“. This error occur because I place <asp:ScriptManager runat=”server” /> element in my page.

Wondering why, I search in internet and hope that I will find one of the solution. After several trial and error finally I can find the solution and it work just fine for me.

To solve the error we need to modify web.config file, add the following under <system.web />

<httpHandlers>
<add  verb=”GET,HEAD” path=”ScriptResource.axd” type=”System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35″ />
</httpHandlers>

Nothing more I can say, but if you get the same error when you work with ASP.NET Ajax try the above solution, and I hope this help.

How To: Include File in ASP.NET Pages

Sometimes programming its just the matter of style, I am not generalize but often I found that we can achieve one goal through many different ways. Lets inspect one of those! By right now I have try three different way on how we put a file in ASP.NET pages. I don’t know which one is the best, but all of the three has the same meaning: we can refer to a file and bring it where ever we like in our ASP.NET pages.

Yes, this is maybe the prefered way because if we include a file and we place it in all of pages -let’s say copyrights footer for example- Later if we want to change the copyrights with the new one, or modify it to something we want, we simply modify it in one place (in our referenced file) rather than go through all of our pages and change it one by one.

How we do this? I have tried three solutions to do that.

1. Using <!– #include file=”[filename].aspx” –>
The first (and maybe the old one) we just write a simple script (as show above) and specify the file we want to include. Place the above script where ever we want content of [filename].aspx appear in pages that referenced it. For security reason always try to include only *.aspx files.

The Differences of ASP.NET Forms and Windows Forms in a Nutshell

I think its quite interesting if we compare two things that has equalities and differences. Now we will talk about Forms (WebForms and WinForms).

As we already know WebForms uses browser as presentation (ASP.NET Forms is no exception) and Windows Forms has its own presentation. So we may agree that WebForms has the strength through its availability and WinForms through its rich user interface.

In this post I will talk about the differences, what I get from both forms (ASP.NET Forms and Windows Forms) at a glance. I hope this post not tedious for those who already familiar with ASP.NET and Windows Forms.

Base Class
An ASP.NET Form inherits Page class (contained in System.Web.UI namespace). Look at the following example:
Presentation page (Welcome.aspx):

<%@ Page Language=”C#” debug=”true” CodeFile=”Welcome.aspx.cs” Inherits=”Welcome.HelloWorldClass” %>

<html>
<head>
<title>Welcome To ASP.NET Form</title>
<script lang=”C#” runat=”server”>
</script>
</head>
<body>
<form runat=”server”>
<center><asp:Label id=”label” Font-Size=”25px” style=”font-weight:bold;” runat=”server” /></center>
</form>
</body>
</html>

 

This is the code behind (Welcome.aspx.cs):

Pagination in ASP.NET

ASP.NET has DataGrid control, and datagrid control has build in support for pagination. What I do in this post is just something like datagrid pagination, but I add two buttons each of them to navigate to previous and next page respectively.

I use ListOfPage class to produce list of page number, you can see more on this class in my previous post here. For simplicity I use array of string as data source, in more common scenario maybe we use data from database, represent it in DataTable then use the DataTable as a data source.

I do the manual pagination in ASP.NET with code behind style. There is I put the code that produce list of page in a separate file (I named it ManualPagination.aspx.cs). The presentation page laid in ManualPagination.aspx which refers to our code behind file.

Let’s start with presentation page! It’s quite simple, this is the source code (ManualPagination.aspx):

<%@ Page Language=”C#” CodeFile=”ManualPagination.aspx.cs” Inherits=”ManualPagination.CodeBehindClass” %><html>
<head>
<title>Manual Pagination in ASP.NET</title>
<style type=”text/css”>
.clr
{
background-color:lightblue;
}
</style>
</head>
<body>
<form runat=”server”>
<asp:Label id=”lblPresentation” runat=”server” />
<p />
<asp:Button id=”btnPrev” text=”Prev” onclick=”btnPrev_Click” runat=”server” />

<asp:Label id=”lblPages” runat=”server” />

<asp:Button id=”btnNext” text=”Next” onclick=”btnNext_Click” runat=”server” />
</form>
</body>
</html>

 

One of the important portion of our presentation page relies on the following code:

CSS in ASP.NET Server Controls, Declaratively vs. Programmatically

ASP.NET controls has a bunch of attributes that take in order the look and feel of every control. For example TextBox server control, if we want the TextBox color turn into specific color we specify the ForeColor attribute to the name of Color defined in Color structure. If we want the TextBox text font appear in Georgia font, set Font-Name attribute to Georgia. ASP.NET TextBox script for above requirements will look something like this:

<asp:TextBox id="txtTest" ForeColor="Red" Font-Name="Georgia" runat="server" />

It looks simple, right?

But wait, for the one familiar with ASP.NET it doesn’t matter, but for everyone who already familiar with CSS maybe there is a bit problem because the attribute name of ASP.NET server controls slightly different with attribute in CSS file. So sometimes we may prefer that the looks and feels of ASP.NET controls ruled within CSS file. And yes, we can do this!

In ASP.NET information within a CSS file can be accessed either declaratively or programmatically, its up to you which one to choose. To make a CSS file visible within our page put this declaration inside our <head></head> tag:

<link rel="stylesheet" type="text/css" href="[filelocation/css_filename.css]" />

Interacting With Get and Post Methods in ASP.NET

There are two common ways to pass data from one page to another, using http Get and Post methods. In Get method, data passed to server using URL encoding. So with Get method data added in URL as query string. For more information on how to retrieve query string values, you can read my previous post here. When we use Post method the URL is still intact, because data passed in HTTP body.

In correlation with ASP.NET, retrieving data passed through HTTP Get and Post methods is quite simple. If data passed with Get method we need the following code to retrieve the data:

Page.Request.QueryString[<param>];

If data passed with Post method we need the following code to retrieve the data:

Page.Request.Form[<param>];

Maybe the problem will more suitable addressed with hand in code practice, so let’s try a simple code! I named the HTML file as methods_source.htm:

<html>
<head>
<title>Using Http Get And Post</title>
</head>
<body>
<form id=”frm_get” action=”get_recv.aspx” target=”_blank” method=”GET” >
<table>
<tr>
<td>Name: </td> <td><input type=”text” id=”txtName” name=”name” /></td>
</tr>
<tr>
<td>Address: </td> <td><input type=”text” id=”txtAddr” name=”addr” /></td>
</tr>
<tr>
<td></td> <td><input type=”submit” value=”Send Using Get” /></td>
</tr>
</table>
</form>
<p />
<form id=”frm_post” action=”post_recv.aspx” target=”_blank” method=”POST” >
<table>
<tr>
<td>Name 2: </td>
<td><input type=”text” id=”txtName2″ name=”name2″ /> </td>
</tr>
<tr>
<td>Address 2: </td>
<td><input type=”text” id=”txtAddr2″ name=”addr2″ /> </td>
</tr>
<tr>
<td></td>
<td><input type=”submit” value=”Send Using Post” /> </td>
</tr>
</table>
</form>
</body>
</html>

Calling Client Script Events in ASP.NET Server Controls

ASP.NET has its own controls (WebControls or HtmlControls) that rendered as elements in a page. ASP.NET server controls declared with ‘asp’ tag (<asp:[control_type] />) and contains runat=”server” attribute. ASP.NET server controls has its own attribute related to a specific control (such as onclick and text for click event and button text respectively).

For example: if we want a click event associated with a button of ASP.NET server control we use this script in our ASP.NET page:

<asp:Button id="btn" onclick="btn_Click" text="Test" runat="server" />

The click event received in onclick attribute and will be handled by btn_Click method. btn_Click is a method that will be called everytime a click occurs in this button control. We can write btn_Click method with any languages that supported by .NET framework.

But how if we want to call client script within ASP.NET server controls? Fortunately it can be accomplished to. Suppose that I have a button of ASP.NET server control but I want a click event of this button handled by Javascript function (in client side) rather than any of .NET languages (in server side).

In this example I use two buttons of ASP.NET server controls. The first button will have click event handled using server script and click event of second button handled via client script. I embed the javascript code inline inside the page, but we can pull it out and place it in separate *.js file then this file is referenced inside our ASP.NET page (expage.aspx):

Retrieving Query String Values in ASP.NET and Javascript

In World Wide Web, a query string is a part of a URL that contains data to be passed to web applications (http://en.wikipedia.org/wiki/Query_string).
The query string is composed of a series of field – value pair. Below is the pattern of query string:
field1=value1&field2=value2&field3=value3

An URL that contains query string can be depicted as follow:
http://test.com/tag?name=alma&role=user
The URL and query string separated by a question mark (?). Query string consist of two parts (field and value), and each of pair separated by ampersand (&). So the example above consists of two query strings which are name and type with value of each field ‘alma’ and ‘user’ respectively.

We can retrieve the query string values programmatically and used that values. Now we will learn how to get the query string values in ASP.NET and Javascript.

Pengenalan Web Part

Ini adalah pengalaman yang saya peroleh baru – baru ini, berkaitan dengan dengan penempatan saya di proyek departemen keuangan. Sebelumnya saya ucapkan terima kasih kepada temen – temen se-tim atas bantuannya selama ini (mas Aan, mas Reno, Anthony-kalau ada yg keliru tolong koreksi ya.-).

Web part merupakan suatu library (file dengan ekstensi *.dll), yang dapat dipasang/ ditempatkan pada halaman web ASP.NET. Jadi suatu webpart akan menempati wilayah atau bagian tertentu dari halaman web ASP.NET. Konsekuensi dari hal ini adalah penggunaan web part dapat meningkatkan reusability, misalnya web part A dapat dipasang pada halaman web_A dan halaman web_B dan juga halaman web_A dapat terdiri lebih dari satu web part misalnya halaman web_A terdiri dari web part A dan web part B.

Dalam .NET, untuk bisa menjadi suatu web part maka suatu kelas harus mewarisi dari kelas yang bernama WebPart(kelas ini terdapat dalam namespace System.Web.UI.WebControls.WebParts). Listing sederhananya dapat kita lihat dalam cuplikan kode berikut ini:

public class FirstWebPart : System.Web.UI.WebControls.WebParts.WebPart

Sedangkan berikut ini syntaks yang diperlukan untuk membuat suatu program ‘hello world’ dari suatu web part:

using System;
using System.Web;
using System.Web.UI.WebControls.WebParts;

namespace TestWebPart
{
    public class FirstWebPart : System.Web.UI.WebControls.WebParts.WebPart
    {

    // mengganti implementasi method Render dari kelas WebPart
       protected override void Render(HtmlTextWriter writer)
       {
           writer.Write("Hello, World...!!!");
       }
    }
}

Tapi yang harus diperhatikan karena kelas ini dimaksudkan sebagai library maka dia tidak dapat dijalankan secara langsung, harus ada suatu halaman web yang menggunakannya dan halaman web tersebut dipanggil lewat browser barulah kita akan melihat hasilnya.
Masih banyak hal yang harus diperhatikan dalam kaitannya dengan penggunaan web part, diantaranya bagaimana menggunakannya melalui halaman web dan juga konfigurasi yang diperlukan. Sampai jumpa lagi