This post explains how to represent business objects with the ObjectDatasource control. It allows you to bind DataBound controls such as GridView, DetailsView and FormView. It also enables you to separate your business logic and data access logic from presentation layer.

The following types can be the data source for the ObjectDataSource Control

• Collections
• ADO.NET Objects
• LINQ to SQL

Collections

You can use the SelectMethod Property for selecting data from a method and TypeName is the type of the object that you are using as source for ObjectDataSource Control.

The sample Type is as follows

Now you can use DataBound controls to bound to the ObjectDataSource control through DataSourceID property.

LINQ to SQL Query

The preferred method of data access is LINQ to SQL. The type can be looks like

Assuming that you have already created the datacontext for LINQ to SQL.

Using Parameters with the ObjectDataSource Control

We can use Select,Insert,Update,Delete and Filter parameters when calling the method with the ObjectDataSource Control.

For example we can write a Update method in the type as follows

The UpdateMethod property of ObjectDataSource control can point to the above method. When you bound this datasource to GridView control it automatically add the update parameters to the ObjectDataSource control’s UpdateParameter’s collection. It uses reflection to match the parameters against

method parameters.

Paging,Sorting, and Filtering Data with the ObjectDataSource Control

The ObjectDataSource Control provides two options for paging and Sorting.

1. UserInterface Paging
2. DataSource Paging

In order to use UserInterface paging you need to bind the GridView control to DataSet,DataView or DataTable. The Drawback of using this option is all the records are loaded into server memory.

In DataSource Paging you can write custom logic or storedprocedure to perform the paging.

Adding and Modifying Parameters

You can use Selecting,Inserting,Updating and Deleting events of ObjectDataSource Control to modify the  parameters that are passed to the methods.

Handling Errors

You can use Selected,Inserted,Updated or Deleted events in order to handle any errors that results from the methods.

Example:

When you sent a request for ASP.NET page, Framework checks for the corresponding class to the page and if the class not exists, Framework compiles the page into a new .NET class and stores the compiled class in the temporary ASP.NET Folder located at

\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files.

In future if request comes to the same page, the page is not compiled again.The previously compiled class is executed and returns to the browser. This process is called ASP.NET Dynamic Compilation.

If the ASP.NET Page is modified corresponding .NET Class is automatically deleted and when new request comes for that page it compiles the modified page into a new .NET Class.

You can even pre-compile your ASP.NET application using aspnet_compiler.exe command line tool. when you pre-compile your application users doesn’t experience the compilation delay for the first request.

• You can disable dynamic compilation for a single , pages in a folder or for entire web site. Use the CompilationMode attribute in <%page%> directive which allows you to disable the dynamic compilation for a single page.

• You can disable dynamic compilation for entire application by specifying CompilationMode attribute in Pages section of the Web.config file.

Disabling the Dynamic Compilation is useful when you have thousands of pages in web site.

Note: You can not disable the  dynamic compilation for pages that include server-side code and pages that contain data binding expressions.

Code-Behind Pages 

ASP.NET Framework allows you create two types of pages. one where you can write page code and declare page controls in a single page. the other way where you can declare UI controls in one page and page code in separate page normally we call this as a code-behind page.

code-behind page work in a different way in ASP.NET 2.0 compared to ASP.NET 1.1. In version 1.1 pages are related by inheritance and in version 2.0 pages are related by inheritance and partial classes.

The problem with the version 1.1 method is any control that you declared in ASP.NET Page needs to be declared in the code-behind file and with exactly same control-ID.

In Version 2.0 the association of ASP.NET Page and Code-Behind page no longer related by inheritance but through a new concept partial classes. It enables you to declare a class in more than one physical-file. Any members of one partial class is accessible to the any other partial class of the same class.

The advantage of using partial classes is declaring a control in ASP.NET Page is available in code-behind page and anything declared in code-behind file will automatically available in Page.

This post speaks about using Panel Control in ASP.NET Pages. Panel Control allows you to work with a group of ASP.NET Controls. You can use it to show or hide a group of controls.

Example:

The Panel control supports the following properties

• DefaultButton When you set a value to this property, the default button in the panel is invoked when you press the Enter Button.
• Direction Enables you to set or get the direction of the text. Possible values are NotSet, LeftToRight and RightToLeft.
• GroupingText Enables you to render the panel control as a fieldset with legend.
• ScrollBars Enables you to display the scrollbars around the panel control.

By default panel renders with the Div tag and when you set the GroupingText property panel renders the fieldset tag.

In order to preserve the page and control data over round trips to the web server, traditionally we are using View State. View State Property maintains information in hidden field and the data is encrypted.

If you disable the View State in your page, the custom controls which used in your page has a chance of losing their state.

To Address the above issue ASP.NET 2.0 has introduced Control State  which is private View State for the control and preserves the state of the control even when you turn off the View State.

Use the Control State property when you are developing the Custom Control by overriding the SaveControlState method to save the data in Control State.

Note that Control State Can not be disabled.

This post explains the some more tips on using Visual C# IDE to enhance developer productivity.

• Solution Configurater  Right click your solution in your IDE then select the ConfigurationManager  you see the following window

where you have the option to select the project for building. We can select the required project in the solution and can you can build the project.

• Solution Wide Comments You can add task lists and comments to your solution. To view the task list for your solution select view menu and click on TaskList option. Ctrl + W, T you will see the following window

You can add the task list items to window by writing the following snippet in the code file.

//TODO Write some code 

Which really helps the developer to set reminders to write the code and also useful to suggest the developers to refactor the code by setting the TaskList comments.

• Snippet Designer      Download the Snippet Designer

The above snippet designer is a plug-in which integrated in to the visual studio IDE which adds a rich and productive experience to the developer.

It allows the developer to write a snippet in the IDE as follows

To insert a snippet for example to write class type class and double tab it inserts class template.

code snippets are really great way to build the code.

Ctrl + K, X is the short cut for insert snippet. You can use Shift + Tab to navigate the categories in the snippet.

• Background Squiggles When you type some code in IDE and if the code having any errors it immediately shows an red mark under the identifier which you have written in the code.

for example:

It shows the above tool tip if the required namespace declaration miss in your code file. No need to write the namespace at the top just press the

Ctrl + . smart tag appears as follows

It automatically inserts the using statement in the using declarations section.

If the method is not defined in your code it generates the method for you

• Expand/Shrink Selection To select the statement in your code  you can use CTRL + ALT, = which allows you to select the logical blocks in your code and CTRL + ALT, –  to unselect the block of code.

• Organizing Using’s You may want to sort the using statements in your code file or you may want to remove the unused using statements. you can do as follows in the IDE

• Camel Case Navigation we all know that we can use arrow keys to move around the code in our file and we can hold the Ctrl key to move around the words and we can use Ctrl + Shift to select the words. Coderush comes with new shortcut Alt+Left and Alt+Right to move around the camel cases in code.

• Anonymous Type  In order to expose anonymous code in public APIs we need to write some type casts. coderush comes with nameanonymous type it creates a new class.

• Extract Method you can select the code and click on extract method in smart window and shows the preview as shown in the window

Here I am summarizing what we have learnt in this post

We will have the following concepts in implementing the Singleton pattern

• We declare a private constructor which prevents other classes to create an instantiation of the singleton class. It also prevents the sub classing.
• We declare a class as sealed so that it can not be instantiated.
• We declare a static variable for holding the reference of a singleton class.
• We declare a public property to return the singleton instance.
• We declare a method for returning the message from the singleton class.

The problem with the above code is it is not a thread –safe code. For example if two threads evaluates the if condition in the above code and both returns the true.

We will rewrite the code for thread safety

The above implementation is thread safe but having the performance issue.

Every time the lock is acquired whenever you request the object.

We can write the above code with out implementing the locks as follows

The static constructor in C# only be called whenever you create a instance for the class.

with Visual studio IDE. They may have to understand the following activities to do their job.

• Understanding Code Developer must be able analyze the relationship between classes and what API it is using for implementing the logic.
• Navigating Code Developer may or may not know where he want to navigate to the code and keep track of visited files in the code.
• Writing & Modifying Code Developers may require to modify the existing code like refractoring which involves make the code readable and fix bugs etc
• Debugging & Testing Understanding the using of debugger tools and writing unit test cases.

Visual studio provides the tools for all the activities mentioned above to make the developer efficient and productive. This post speaks about using the tools available in VS 2008 sp1. It also discusses about the tool coderush express which Microsoft partnering and allows the developers to download and use freely.

 Download Coderush for C#

1. One of the short cut for goto definition is F12

For example you have an identifier and you want to know where it is declared just press F12. If the identifier is not your project then it shows the metadata of the identifier. eg we are viewing string class

2. When you bring the code definition windows by Ctrl + W, D  you will see the following picture

When you move the code on top window it shows the declarations in the code definition window.

You can use Ctrl + Shift, 8 to come back from the declaration. F12 is for go to the definition of window and Ctrl + Shift, 8 is to come back to the origin.

You can also view the Navigation stack by Ctrl –.

3. To find all the references in your project for a particular method or type you can use Shift + 12 which shows the following window in IDE

To navigate to the references list window you  can use F8.

4. Some times when you are working on a really big project and you want to know which file you are actively using and you want know where it is in solution explorer. You can find the file in the solution explorer by going to Tools-Options dialogue box and selecting the General option under the projects solutions.

You can track the active item in solution explorer by checking the above option.

5. Code rush express short cut when you want to go to the file use

   Ctrl + Alt + F you will get the following window

It also filters the files based on the input and camel case .

If you want to go to any type or method in your project then you can use coderush shortcut   Ctrl + Shift , Q it show the following window 

If you want to see the identifier where it is used in the project you can use

Ctrl + Alt , U.  you can use tab key to navigate between the identifiers.

6. To navigate to the open files in the IDE you can use Ctrl  + Tab

you can also use Ctrl + Alt + Down to bring the following window

7. Viewing the class designer

you can view the class designer of the class and it dynamically updated whenever you change the class in code definition window.

summarizing what we have learned so far

In the next post I will explain about more tips.

The ?? operator in C# called null-coalescing operator is used to define a default value for a nullable value types and reference types. It returns the left-hand operand if it is not null and returns right-hand operand if it is null.

example

// ?? operator example

. int? x = null;

int y = x ?? –1;

// Here the value of y will be –1.

int i = GetValue() ?? default(int);

Assigns the return value of the method to i if  return value is not null other wise it assigns default value

It can be used with reference type as follows

string s = GetStringValue(); // ?? also works with reference types. // Display contents of s, unless s is null, // in which case display "Unspecified". Console.WriteLine(s ?? "Unspecified");

Using keyword in C# can be used as directive and as well as statement.

When you use using as Directive you will get the following advantages

• You can use the types in a namespace by declaring with using keyword.

        example: using Systetm.Web;

• You can define a alias for the nested namespaces

       example: using alias = CompanyName.ProjectName;

When you use using as Statement it defines the scope and allows the programmer to release the resources used by the object in the defined scope.

The object mentioned in the using statement must implement IDisposable interface. A using statement is can be exited when the end of the using statement is reached.

example :

Font font2 = new Font("Arial", 10.0f);
using (font2)
{
    // use font2
}

Multiple objects can be used in with a using statement, but they must

be declared inside the using statement.

example:

using (ResourceType r1 = e1, r2 = e2, …, rN = eN) statement

it is equivalent to the following code

using (ResourceType r1 = e1)

   using (ResourceType r2 = e2)

      …

         using (ResourceType rN = eN)

            statement

Windows Azure is an operating system for windows cloud. This post speaks about key features and how can we use windows Azure.

What does this mean and what is windows cloud these questions will come up in mind????

Windows cloud is a set connected servers on which developers can install and run services. we can also store and retrieve data from the servers.

Imagine you are building a desktop application it might include the following steps

• Selecting the hardware for the application
• Selecting the storage mechanism
• Writing some Job schedulers
• Writing an application installer for the application.
• and more…..

The above steps are normally done by every developer in a day-to-day activities.

So Windows Cloud replacing all the above steps.

What is missing on the windows cloud? Operating System!!!!!!!!!

This operating system provides the same facilities as normal OS But on a set of connected servers.

Key Features for the service developers

• Automated service management : you write your code and rules windows azure take care of deploying your code run on the machines.
• Powerful Hosting Environment: Virtualizes the environment
• Scalable, available storage: which contains blobs,tables and queues
• Rich Developer experience: The developer can simulate everything that happens on windows cloud.

In the next post i am going to explain about writing a sample application on windows Azure.