Computer Programming

Wednesday, August 7, 2013

August 07, 2013

Output Caching with the VaryByParam Attribute

Example of output Caching with the VaryByParam Attribute

<%@ Page Language="C#" %>
<%@ OutputCache Duration ="60" VaryByParam ="Name" %>

<!DOCTYPE html>

<script runat="server">

protected void Page_Load(object sender, EventArgs e)
{

}

protected void Button1_Click(object sender, EventArgs e)
{
if (IsPostBack )
{
Name.Visible = false;
Label3.Visible = false;
Button1.Visible = false;
Label2.Text = "the output of this page was cached for" + Name.Text + "The current time is" + DateTime.Now.ToString();
}
}
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>

<asp:Label ID="Label3" runat="server" Text="Please Enter your name:"></asp:Label>
<asp:TextBox ID="Name" runat="server"></asp:TextBox>

<br />
<asp:Label ID="Label1" runat="server"></asp:Label>
<br />
<asp:Label ID="Label2" runat="server"></asp:Label>
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />

</div>
</form>
</body>
</html>

Output

c# Controls Events Validation Windows Forms

August 07, 2013

Validating Input Controls in windows forms C#

Data entered by user, should be valid and properly formatted, Otherwise a lot of resources could be wasted in fixing the problems that could be arise due to incorrect data format. Data should be properly checked according to the input criteria. Windows forms provides some ways to validate input in your application.

Masked TextBox Validation

We often requires some data like contact number in a well-defined format and also correct no of digits. This problem can easily be solved by using MaskedTextBox in windows forms. MaskedTextBox displays some formats to the user. If user types a wrong entry then this textbox automatically reject that input.

Just add a MaskedTextBox control and look out the mask property. There are approx. 9 predefined masks such as Phone number, zip code, Numeric digits etc. as in following screenshot:

Mask options of Masked TextBox in windows forms

There is no mask for mobile no in the above masks, so we have to create a new mask. Use the last mask i.e. custom mask and insert ten zero’s in the mask textbox just below the list of mask because mobile no is of ten digits, and our new mask has been created.

Event-Driven Validation

Each input control has a Validating event that occur whenever the control requires data validation. Validating event enables you to prevent from shifting focus from the control being validated to another control until validation has been completed.

To check whether the textbox is blank or not, we will simply check this by using the following line of codes in validating event of textbox in C# language.

private void textBox1_Validating(object sender, CancelEventArgs e)

{

if (textBox1.Text == string.Empty)

{

MessageBox.Show("Textbox is empty");

}

Just like above code we can validate any other control using some lines of code. There is an argument e of type CancelEventArgs, which can be used to cancel the validating event if required input has been entered by user.

Displaying message when validating the textbox

As in above screenshot if the textbox left empty by the user then a message has been displayed written above. This message can be displayed by any of the message box, status strip etc.

Tuesday, August 6, 2013

August 06, 2013

How to use caching in ASP.NET

Top related article

Output Caching with the VaryByParam Attribute

Introduction
Caching as the name suggest, is used to store data temporarily either on a Web server or on the client-side. Caching is useful in situation where several programs continually access the same set of data. This data can be easily stored in a cache and used in future. Accessing a database in an ASP.NET page is generally a slow and time-consuming process that involves connecting to the database and retrieving data from it. Caching is the best way to improve the performance of your Web application since it allows you to access data from the cache itself, which is quicker than if you were to retrieve the data from the database on each request. Therefore, caching not only reduces the processing time of a Web application, but also reduces network traffic; thereby improving the performance of your Web application and enhancing user experience.

Example of caching using output caching

<%@ Page Language="C#" %>
<%@ OutputCache Duration ="10" VaryByParam ="none" %>
<!DOCTYPE html>
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
Label2.Text = DateTime.Now.ToString();
}
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label ID="Label1" runat="server" Text="The below displayed time was cached for 10 seconds keep refreshing the page to see the changes"></asp:Label>
</div>
<asp:Label ID="Label2" runat="server" Text=""></asp:Label>
</form>
</body>
</html>

Output

Here in this example time label will changed after 10 second.

VaryByParam Attribute

The VaryByParam attribute is used to cache different copies of a Web page when it is generated dynamically, based on the parameters received in the form of HTTP POST or HTTP GET.

c# Controls Windows Forms

August 06, 2013

LinkLabel control in windows forms C#

Label control is used to display the text such as Name, address, title and so on. The text shown through Label control cannot be edited directly by the user. Most often this control is used for providing information of another control in the windows form.

LinkLabel control is, derived from the label control, used to display text as a link. Link may be of a windows form or a website depending on the requirements. It has all the properties of Label control as well as its own properties. The commonly used properties of LinkLabel control are:

ActiveLinkColor: used to get or set the color used to display the active link. It is of type Color.
linkLabel1.ActiveLinkColor = Color.Blue; This code sets the color to blue of an active link in C#.
DisabledLinkColor: used to get or set the color used to display the disabled link. It is also of type Color. linkLabel1.DisabledLinkColor = Color.Blue; This code sets the color to blue of an disabled link in C#.
LinkColor: used to get or set the color of the text on the LinkLabel control. It is also of type Color. linkLable1.LinkColor = Color.Blue; This code sets the color of the text to blue in C#.
LinkVisited: used to get or set a value indicating whether a link should be displayed as though it were visited. It is of type Boolean and default value is false.

LinkClicked event occurs when the link is clicked by the user. This event has an event argument of LinkLabelLinkClickedEventArgs which returns the link that was clicked by the user. The structure of this event is as follows in C#:

private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)

{

}

Writing the following code in this event will show a new form

Form2 frm = new Form2();

frm.Show();

To create a link to a website, we should use following code:

System.Diagnostics.Process.Start(“http://dotprogramming.blogspot.in”);

In the above code the method Start() starts the default browser with the given URL.

Monday, August 5, 2013

WPF XAML

August 05, 2013

Basics about XAML in context of WPF Application

XAML, stands for eXtensible Application Markup Language, is a declarative XML based language used for initializing structured values and objects. In the context of WPF, XAML is used to describe visual user interface. The GUI created in XAML can be expressed using any .NET language like C# or VB.

As this is simply based on XML, programmers are able to share and edit content amongst themselves without compilation. Whenever you will create a page or a window in WPF, it will create a XAML document and a code behind file, which together creates the page or window.

Here is the basic XAML code for creating a textblock in Grid element.

In the above code use <TextBlock> element to identify the TextBlock control. The FontSize property is used to get or set the font size of the content of the element. Here font size of the text block is 30 pixels.

Horizontal alignment property is used to get or set the horizontal alignment of this element when it is within a parent element like a panel etc. The horizontal alignment may be center, left, right and stretch according to programmer’s requirement. The default value is Stretch.

Vertical alignment property is same as horizontal property. It is also may have four values i.e. center, left, right and stretch programmer’s requirement. The default value is Stretch.

We can also use the above properties like the following code:

<TextBlock Text="My First WPF Application">
<TextBlock.FontSize>30</TextBlock.FontSize>
<TextBlock.HorizontalAlignment>Center</TextBlock.HorizontalAlignment>
<TextBlock.VerticalAlignment>Center</TextBlock.VerticalAlignment>
</TextBlock>

The window will be look like the following screenshot:

Both type of syntaxes are same. There are many more properties for each elements which will use as per the requirements.

Sunday, August 4, 2013

August 04, 2013

How to use menu control in ASP.NET

About menu control

The Menu control is another navigation control, which is also used to display site navigation information . The Menu control can however , displays the site structure vertically as well as horizontally. It can be used as a databound control , for example , binding the menu control with a SiteMapDataSource control. It can also retrieve the data to be displayed from the items that are added to the Item collection of the Menu control at runtime. The Menu control supports binding data with hierarchical datasource, such as XML files. You can also add the database items to the Menu control at runtime using the Item collection of the Menu control . The Menu control consists of one or more MenuItems properties displayed at different levels of hierarchy. Each MenuItem, in turn, consists of properties to set the style of the individual MenuItem. The menu control contains two types of menus:

Static menu -- This type of menu is displayed completely with all the menu options on the screen. The entire structure of the static menu, including the parent menu items and their sub menus, is visible.
Dynamic menu -- This type of menu contains static part which is displayed on the screen as well as the dynamic part which appears when user passes the mouse pointer over the static part of the menu.

Example

first take a "sitemap" file for binding menu control. Right click on your application name in solution explorer and select Web.sitemap file.

A sitemap is a xml file which include different siteMapNode.

<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
<siteMapNode url="http://dotprogramming.blogspot.in" title="Programing" description="Its world best programming site">
<siteMapNode url="http://www.google.com" title="Google" description="" />
<siteMapNode url="http://www.msn.com" title="microsoft" description="" />
<siteMapNode url ="http://pc-gadgetworld.blogspot.in" title ="pc-gadget" description ="" >
<siteMapNode title ="left child" />
<siteMapNode title ="right child " />

</siteMapNode>
</siteMapNode>
</siteMap>

Diagrammatic view of sitemap file

Binding Menu with Sitemap file

<%@ Page Language="C#" %>
<!DOCTYPE html>
<script runat="server">
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>

<asp:Menu ID="Menu1" runat="server" DataSourceID="SiteMapDataSource1" Orientation="Horizontal" StaticDisplayLevels="2">
</asp:Menu>
<asp:SiteMapDataSource ID="SiteMapDataSource1" runat="server" />
</div>
</form>
</body>
</html>