Wednesday, November 17, 2010

Step By Step Guide to implement Linq to Sql class

I realized the benefits of Linq to Sql Classes while developing this forum. This is the dot net frameworks 3.5's powerful feature. I want to tell you little bit about the advantages of linq to sql classes.

  • SQL Injection Proof.
  • Intellisense
  • Compile check when database changes
  • Faster development
  • Auto-generated domain objects that are usable small projects

  1. Open Visual Studio 2008 File-->New-->ASP.NET WEBApplication.
  2. Give name as "Forum_Linq to SQL".
  3. Goto Solution Explorer and right click on "Forum_Linq to SQL".
  4. Ensure your project target framework as Dotnet Farmework 3.5, cause L2S works only on 3.5 framework. For this right click the "Forum_Ling to SQL" Goto Properties change Target Framework as 3.5.
Now In Solution Explorer Right click on Forum_Ling to SQL choose Add-->New Item. below mentioned  window will come. In that choose Linq to Sql classes and clcik Add button.

Now connect your Database in server explorer and drag and drop the tables to DataClasses1.dbml file. It will automatically converted into a class. See the image below.
Now we will see how to retrive data from this forum_user class. For this first we will create the object for the datacontext. Datacontext means it point to the dbml file which is created by us. In this project the datacontext name as "Dataclasses1DataContext". See the code below
 using System;
using System.Collections.Generic; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Linq; namespace Forum_Linq_to_SQL {
public partial class _Default : System.Web.UI.Page
protected void Page_Load(object sender, EventArgs e)
GridView gv = new GridView();
DataClasses1DataContext obj = new DataClasses1DataContext();
var user = (from c in obj.Forum_Users select c).ToList();
gv.DataSource = gv;

How to  Insert the new record into the Forum_user class?

DataClasses1DataContext obj = new DataClasses1DataContext();
Forum_User user = new Forum_User();
user.UserId = "xxxxx";
user.Pwd = "xxxx";
How to  Edit the record into the Forum_user class?
DataClasses1DataContext obj = new DataClasses1DataContext();
var user = (from c in obj.Forum_Users where c.UserId=="xxxxx" select c).First();
user.Pwd = "zzzz";
How to Delete the record into the Forum_user class?
DataClasses1DataContext obj = new DataClasses1DataContext();
var user = (from c in obj.Forum_Users where c.UserId == "xxxxx" select c).Single();

How to Join two tables?
DataClasses1DataContext obj = new DataClasses1DataContext();
var user = (from c in obj.Forum_Users join s in obj.Forum_UsersTwo on s.UserId equals c.UserId select new {c.UserId,s.username}).First();

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Wednesday, November 10, 2010

Dynamic Combobox in

I provide you very simple example.This is just for your reference only. You can recreate that code based on your requirement. Look at the aspx code here I was used the asp:UpdatePanel  for reload the page without referesh.
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
<asp:UpdatePanel ID="UpdatePanel1" runat="server">

now look at the code behind in c#
using System;
using System.Collections;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace DynamicCombo
public partial class _Default : System.Web.UI.Page
protected void Page_Load(object sender, EventArgs e)
if (!IsPostBack)
DropDownList drplist2 = new DropDownList();
int count = 0;
ArrayList arraylist = new ArrayList();
drplist2 = new DropDownList();
drplist2.ID = "drplist2" + Convert.ToString(count);
drplist2.AutoPostBack = true;
drplist2.Attributes.Add("runat", "server");
drplist2.SelectedIndexChanged += new EventHandler(drplist1_SelectedIndexChanged);
Session["arraylist"] = arraylist;
Session["count"] = count;
ArrayList arraylist = (ArrayList)Session["arraylist"];
for (int i = 0; i
DropDownList dd=(DropDownList) arraylist[i];
dd.ID = "drplist2" + Convert.ToString(i);
//dd.AutoPostBack = true;
//dd.Attributes.Add("runat", "server");
// dd.Items.Add("Mango");
dd.SelectedIndexChanged += new EventHandler(drplist1_SelectedIndexChanged);
protected void drplist1_SelectedIndexChanged(object sender, EventArgs e)
DropDownList drplist2 = new DropDownList();
ArrayList arraylist = (ArrayList)Session["arraylist"];
int count = (int)Session["count"];
drplist2.ID = "drplist2" + Convert.ToString(count);
drplist2.AutoPostBack = true;
drplist2.Attributes.Add("runat", "server");
drplist2.SelectedIndexChanged += new EventHandler(drplist1_SelectedIndexChanged);
Session["arraylist"] = arraylist;
Session["count"] = count;

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Little bit about ASP.NET Special Folders

Little bit about ASP.NET Special Folders
With the release of ASP.NET 2.0, Microsoft has greatly increased the power of ASP.NET by introducing a suite of new features and functionalities.  
ASP.NET defines several special folders. When a new Web site is created the App_Data folder is created by default; it can contain a SQL Server 2005 Express Edition database, another database, or an XML data file that will be used in the Web site.
From ASP.NET 2.0 versions Microsoft provided 8 integration directories to integrate different resource in your application. It is also called Data Directory. Special folders that exist in ASP.NET that can be added to your Web site are as below:
App_Browsers reserve this folder name for storing browser definition files. Browser definition files are used to determine the client browser capabilities. Browser definition files have .browser extension. These files are often used to help support mobile application.  
App_code folder can contain source code for utility classes as well business objects (.cs, .vb and .jsl files). Classes that are present in App_Code folder are automatically complied when your web application complied. Arbitrary file types can be placed in the App_Code folder to create strongly typed objects.
For example: placing Web service files (.wsdl and .xsd files) in the App_Code folder creates strongly typed proxies. Code present in App_Code is automatically referenced by Application.  
App_Data is used to store file that can be used as database files (.mdf and xml files). App_Data folder is used by ASP.NET application for storing ASP.NET application local database. Developers can also use this folder for storing data for their ASP.NET Application.  
App_GlobalResources folder contains resources (.resx and .resources files) that are compiled into assemblies and have a global scope. Resource files are used to externalize text and images from your application code. This helps you to support multiple languages and design-time changes without recompilation of your source code. Resource files are strongly typed and can be accessed programmatically.  
App_LocalResources folder contains resources (.resx and .resources files). The same files that are being contained by App_GlobalResources but files located in this folder are only available to a particular project, web page, master page or web user control. 
Contain subfolders that each defines a specific theme or look and feel for you Web site. A these consist of files (such as .skin, .css and image files) that defines the appearance of Web pages and controls.  
Contains Web references files (.wsdl, .xsd, .disco, and .discomap files) that define references to Web services.  
Bin folder contains compiled assemblies (.dll files) for code that you want to reference in your application. Assemblies in Bin folder are automatically reference in your application. Special folders can be added to a Web site from the Visual Studio menu system. Typically this involves right-clicking the Web Application project and selecting Add ASP.NET folder.

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ASP.NET Themes And Skins

Steps to Create Themes
Creating A theme
Step 1: Right click the root folder in solution explorer and right click. A popup menu will appear. In that select Add ASP.NET Folder à Theme
The theme folder names “default” will be created under App_Themes Folder
Step 2:  Add a css file by right clicking the default folder and select Add New Item
You can add a folder for images (if u needed)
Add a skin file by right clicking the default folder and select Add New Item
The following is the sample code for skin file
<asp:Button runat="server" class="btn"/>
<asp:TextBox CssClass="TextBoxCss" runat="server">asp:TextBox>
<asp:DropDownList runat="server"  Height="22px" CssClass="TextBoxCss">asp:DropDownList>
<asp:Image ImageUrl="Images/SmallCalendar.gif"  runat="server" CausesValidation="false" skinid="SmallCalendar"/>

Step 3: Add as many skins as you need by repeating the step 1 and setp 2

Using it in Our Application

The namesapace for theme is System.Web.UI.PageTheme

There are many ways to use the Theme.
In Page Directive we can assign the theme property Like this,
        <%@ Page Title="" Language="VB" Theme="Blue"%>.

But this is Static.

If u need to change the theme dynamically then u need to change the theme in Page_PreInit event of the page.

  Private Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit
        If Request.Cookies("Theme") IsNot Nothing Then
            Page.Theme = DirectCast(Request.Cookies("Theme").Value, String)
            Page.Theme = "Blue"   'Default Theme
        End If
    End Sub

In the above code  I used to cookie to save the theme name. The following code is used to load the available themes in a drop down list

     Dim themes As String()
                Dim thmname As String
                Dim li As ListItem
                themes = Directory.GetDirectories(Server.MapPath("~/App_Themes"))
                For Each thm As String In themes
                    thmname = Path.GetFileName(thm)
                    li = New ListItem
                    li.Text = thmname
                    li.Value = thmname
                    If thmname = Page.Theme Then
                        li.Selected = True
                        li.Selected = False
                    End If

“ChangeTheme” is the name of the Drop down list. Write this code in Form_Load event.

The following code is used to save the cookie. 

        If Not (Request.Cookies("Theme") IsNot Nothing) Then
            Response.Cookies("Theme").Expires = DateTime.Now.AddDays(-1)
        End If
        Dim cookie As HttpCookie = New HttpCookie("Theme", ChangeTheme.Text)
        cookie.Expires = DateAdd(DateInterval.Day, 30, Now)

Write this in Dropdown list selected index changed. The above cookie is saved in the browser for 30 days. You can also use session variables.

In General, if we want to implement the theme to all the pages of a project, then you must derive a base class of System.Web.UI.Page And all the pages must use this derived class instead of System.Web.UI.Page.

The theorey part is as follows


ASP.NET Themes and Skins

A theme is a collection of property settings that allow you to define the look of pages and controls, and then apply the look consistently across pages in a Web application, across an entire Web application, or across all Web applications on a server.

Themes and Control Skins
Themes are made up of a set of elements: skins, cascading style sheets (CSS), images, and other resources. At a minimum, a theme will contain skins. Themes are defined in special directories in your Web site or on your Web server.


A skin file has the file name extension .skin and contains property settings for individual controls such as Button, Label, Textbox, or Calendar controls. Control skin settings are like the control markup itself, but contain only the properties you want to set as part of the theme. For example, the following is a control skin for a Button control:
You create .skin files in the Theme folder. A .skin file can contain one or more control skins for one or more control types. You can define skins in a separate file for each control or define all the skins for a theme in a single file.
There are two types of control skins, default skins and named skins:
v     A default skin automatically applies to all controls of the same type when a theme is applied to a page. A control skin is a default skin if it does not have a SkinID attribute. For example, if you create a default skin for a Calendar control, the control skin applies to all Calendar controls on pages that use the theme. (Default skins are matched exactly by control type, so that a Button control skin applies to all Button controls, but not to Link Button controls or to controls that derive from the Button object.)
v     A named skin is a control skin with a SkinID property set. Named skins do not automatically apply to controls by type. Instead, you explicitly apply a named skin to a control by setting the control's SkinID property. Creating named skins allows you to set different skins for different instances of the same control in an application.

Cascading Style Sheets

A theme can also include a cascading style sheet (.css file). When you put a .css file in the theme folder, the style sheet is applied automatically as part of the theme. You define a style sheet using the file name extension .css in the theme folder.

Theme Graphics and Other Resources

Themes can also include graphics and other resources, such as script files or sound files. For example, part of your page theme might include a skin for a TreeView control. As part of the theme, you can include the graphics used to represent the expand button and the collapse button.
Typically, the resource files for the theme are in the same folder as the skin files for that theme, but they can be elsewhere in the Web application, in a subfolder of the theme folder for example. To refer to a resource file in a subfolder of the theme folder, use a path like the one shown in this Image control skin:

You can also store your resource files outside the theme folder. If you use the tilde (~) syntax to refer to the resource files, the Web application will automatically find the images. For example, if you place the resources for a theme in a subfolder of your application, you can use paths of the form ~/SubFolder/filename.ext to refer to resource files, as in the following example.

Scoping Themes

You can define themes for a single Web application, or as global themes that can be used by all applications on a Web server. After a theme is defined, it can be placed on individual pages using the Theme or StyleSheetTheme attribute of the @ Page directive, or it can be applied to all pages in an application by setting the element in the application configuration file. If the element is defined in the Machine.config file, the theme will apply to all pages in Web applications on the server.

Page Themes

A page theme is a theme folder with control skins, style sheets, graphics files and other resources created as a subfolder of the \App_Themes folder in your Web site. Each theme is a different subfolder of the \App_Themes folder. The following example shows a typical page theme, defining two themes named BlueTheme and PinkTheme.


Global Themes

A global theme is a theme that you can apply to all the Web sites on a server. Global themes allow you to define an overall look for your domain when you maintain multiple Web sites on the same server.
Global themes are like page themes in that they include property settings, style sheet settings, and graphics. However, global themes are stored in a folder named Themes that is global to the Web server. Any Web site on the server, and any page in any Web site, can reference a global theme.

Theme Settings Precedence

You can specify the precedence that theme settings take over local control settings by specifying how the theme is applied.
If you set a page's Theme property, control settings in the theme and the page are merged to form the final settings for the control. If a control setting is defined in both the control and the theme, the control settings from the theme override any page settings on the control. This strategy enables the theme to create a consistent look across pages, even if controls on the pages already have individual property settings. For example, it allows you to apply a theme to a page you created in an earlier version of ASP.NET.
Alternatively, you can apply a theme as a style sheet theme by setting the page's StyleSheetTheme property. In this case, local page settings take precedence over those defined in the theme when the setting is defined in both places. This is the model used by cascading style sheets. You might apply a theme as a style sheet theme if you want to be able to set the properties of individual controls on the page while still applying a theme for an overall look.
Global theme elements cannot be partially replaced by elements of application-level themes. If you create an application-level theme with the same name as a global theme, theme elements in the application-level theme will not override the global theme elements.

Properties You Can Define Using Themes

As a rule, you can use themes to define properties that concern a page or control's appearance or static content. You can set only those properties that have a ThemeableAttribute attribute set to true in the control class.
Properties that explicitly specify control behavior rather than appearance do not accept theme values. For example, you cannot set a Button control's CommandName property by using a theme. Similarly, you cannot use a theme to set a GridView control's AllowPaging property or DataSource property.
Note that you cannot use expression builders, which generate code expressions for assignment in a page at compile time, in themes or skins.

Themes vs. Cascading Style Sheets

Themes are similar to cascading style sheets in that both themes and style sheets define a set of common attributes that can be applied to any page. However, themes differ from style sheets in the following ways:
v     Themes can define many properties of a control or page, not just style properties. For example, using themes, you can specify the graphics for a TreeView control, the template layout of a GridView control, and so on.
v     Themes can include graphics.
v     Themes do not cascade the way style sheets do. By default, any property values defined in a theme referenced by a page's Theme property override the property values declaratively set on a control, unless you explicitly apply the theme using the StyleSheetTheme property. For more information, see the Theme Settings Precedence section above.
v     Only one theme can be applied to each page. You cannot apply multiple themes to a page, unlike style sheets where multiple style sheets can be applied.

Security Considerations

Themes can cause security issues when they are used on your Web site. Malicious themes can be used to:
v     Alter a control's behavior so that it does not behave as expected.
v     Inject client-side script, therefore posing a cross-site scripting risk.
v     Alter validation.
v     Expose sensitive information.
v     The mitigations for these common threats are:
v     Protect the global and application theme directories with proper access control settings. Only trusted users should be allowed to write files to the theme directories.
v     Do not use themes from an untrusted source. Always examine any themes from outside your organization for malicious code before using them on you Web site.
v     Do not expose the theme name in query data. Malicious users could use this information to use themes that are unknown to the developer and thereby expose sensitive information.

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