Code Garage

My First MVC 3 Project

2011-03-30T21:24:00.000-07:00

Run you Visual Studio 2010 (i used the Express Edition). Select the File menu and then New Project.

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On the window dialog, select which language you want to use. In this case i used C#. As you click on it, it will scroll down more menus. Select Web. Now, look at middle section of the window. Select ASP.NET MVC 3 Web Application. Name the project and solution as StudentMVC.

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Click Ok and now another window dialog appears. I chose Empty Project because i prefer to create this project from the scratch. If i chose Internet Application the Visual Studio 2010 would provide predefine features on the new project such as Home and Accounts controllers.

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By default the empty MVC 3 project comes with several important folders such as Controlers,Models and Views.

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Before working further, you need to create a small database that will be used in this project. Select the Solution Name, right click, select Add then New Item.

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When the window dialog appears select Data and SQL Server Database. Name your database Student.mdf.

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Click Yes on confirming dialog.

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On Solution Explorer you will see a new folder App_Data with 2 files inside it. They are Student.mdf and Student.ldf

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Double click on Student.mdf and the Database Explorer will appear.

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The next step is to create Student table which then will be used to keep the information when we test the program.

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The table consists of 4 fields. ID which is an integer , auto incremented identity (Picture 11 - 15) and set as a primary key. Others are Firstname,Lastname and Age.

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After Student is created, you need to create a data access to read and write the information into that table. Select Models folder on Solution Explorer, right click and select Add then New Item.

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When the window dialog appears, select Data and LINQ to SQL Classes. Name our datasource as StudentDB.dbml.

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After StudentDB.dbml has been created, another window will appears. Select Database Explorer. Drag the Student table from Database Explorer to this window. The Student class diagram then is created.

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On Solution Explorer you can see new files have been created inside Models.

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Now, click on Controllers folder.

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Right click , select Add and Controller.

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Name our new Controller as StudentController.

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If you open StudentController.cs you will see that by default Index function is created by Visual Studio.

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Then we need to create a View to display the Index page of the StudenController. Focus your mouse on Views folder, right click , select Add, New Folder and name that new folder as Student. Actually the name Student was taken from the StudentController name. If later on you create ExamResultController, you need to name the next new folder as ExamResult.

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Now we need to add a new view page in Student folder.

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At the time you add new view page, the window dialog will appear. Put Index in View Name text box. This given name is corresponded to the Index function name we found on StudentController.cs as seen on Picture 26.

Visual Studio provides 2 view engine you can choose from. One is Razor and the other one is ASPX. Lets try the Razor.

Because we are going to use this view to post a new student information to database, we should select the Student data model.

Next is to select Create template then tick on Create as a partial view.

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Index.cshtml has been created.

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Double click on our new view page and remove the bottom part of the code as seen in the red cicle on the picture below.

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Open your Global.asa. Picture 33 shows by default the web site is routed to Index view page in Home controller.

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Rename Home to Student because in this project StudentController is the only controller we have.

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Run the project. The Index is working.

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Eventhough our Index is working already, it doesn't means it is ready to be used to post a new student detail.

Open StudentController.cs which is located in Controllers folder. We need to add an overloading method which receives Student object. Picture 36 shows that we now have the second Index method. The differences between the second and the first one are , the second starts with HTTPPost attribute line which basically telling the compiler than anything that is posted from Index view page will be processed by this method. The second one is the input parameter as i mentioned before.

Inside the second Index method, you can see how the new Student object is saved into the database.

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Lets try to post a new student detail. I used Joe Harding as dummy student detail.

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After submitting the new student detail , now lets open your Database Explorer. Open the Student table and shows the data.

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We just successfuly recorded a new Student detail into our database by using MVC 3

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Source

Protect Your Password with Popped Up Keyboard

2011-03-15T22:01:00.000-07:00

Have ever heard trojan virus that could steal your password while you are logging in to your online internet banking ? Basically that virus contains a routine that detecting any keystroke you type on login page and send it to the hackers computer. The hacker would use that password to break in into your online account and rip you off.

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So, i have an idea to create a JQuery plug in to anticipate this issue. I copied this idea from Westpac Internet Banking. It is a popped up keyboard which would appear at the time the user focus their mouse on the password text box.

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Instead of typing ,this popped up keyboard only allows the user to use their mouse to click. By this way we have deceived the trojan virus that may be running on user computer. That virus won't get anything.

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Source

Singleton Pattern, The Example

2011-03-08T20:37:00.000-08:00

Singleton pattern is used when we want to create the only instant of the a class that can be accessed globally within the application. The implementation of Singleton pattern can be found on Menu. Menu is shared and accessed from any part of the program. Singleton guarantees that all part of the application is refering to the same and the only menu.

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In this example, i created the scenario where the company information needs to be shared across the application, such as for drop down list etc. So, rather than letting the application to repeatedly read the database to get the company information, i used Singleton to read it once and share it other parts of the programs when they need it.

To create a singleton class, i set the constructor to be private (see Picture 1). That means i prevented the LookUp class to be instantiated directly. Then the second i did was to create a public method that return a static private instant of the class. Everytime this method is called, it will check if there is any instant of the class has been created before. If not, it would create a new instant. Otherwise, it would return the existing one.

To make sure this singleton stays working as it is supposed to be even in multithreaded scenario,i used lock.lock is a function to syncronize the call from different threads. It behaves like a traffic light that allows every single thread to have its own turn, one after another.

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To test my singleton class, i created two instant variable. One is m_first and the other one is m_second (see picture 2).Both will get a LookUp instant after the getInstance method is called. An this method requires one input parameter that is used for indicator only. It will indicate which call that actually creates the instant.

Another method is Print. When it is executed it will show the caller and all company information read from the database.

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As you can see on above picture, the second call didn't create a new instant but return the already existing one.

Source

Prototype Pattern,The Example

2011-03-06T18:58:00.001-08:00

Prototype pattern is about creating one instant of object and then use that object to create a clone of that object. So, if Banana is a class, you just need to create one instant of Banana, and clone that instant to create the second one and so forth. Some said it would reduce the object initialization time, compared when we create an instant using new statement.

There are two type Prototype pattern. One is shallow prototyping and the other one is deep prototyping. On Shallow prototyping it only clones the parent object but not any aggregated object inside it. So, it there is an object called FarmDetail inside Banana,that object will not be cloned.

In the other hand, on Deep prototyping, it will clone everything, including all aggregated objects inside that instant. On our scenario as seen on Picture 1 below, the aggregated object is Result.

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In .NET we use MemberwiseClone to create a clone of the current instant as seen on Picture 2. But to clone complex object, it is a good way to use BinaryFormatter as seen on Picture 4.

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The implementation of this pattern can be seen on Picture 5 below. Instead of creating a new instant by using new statement repeatedly, we only need to do it once. The instant we have created then is used as a master copy to create another instant by cloning.

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Source

Factory Pattern , The Example

2011-03-05T03:26:00.001-08:00

From my understanding Design Pattern is a technique in programming to reduce recreation of duplicated methods or functionalities. Sometimes when we develop a huge program we unintentionally create a duplicated methods in our codes.When the program get bigger,it is like a jungle.It makes us hard to see the specific objects we are looking for. If it keeps going like this,on and on,we would face a risk of loosing productivity. It would make us difficult to fix bugs as it happens.

Design Pattern also brings a significant quality for the code we write. It makes the program more efficiently compiled and debugged.It also possibly improve the performance of program as a whole when it runs.

This article is about Factory pattern. It is named Factory because the way it operates is like a factory in real world. Factory produces things based on the incoming orders. And that orders could be repeatedly the same one, or could be not.

Just like in our community.Just assume every family eat bread. They could or couldn't eat the same type of bread. But rather than letting every family makes their own bread which is time consuming, why don't we just create a factory to serve their needs. The factory that provides any type of breads those family needs.

The same way happens in programming. Picture 4 shows how the GetStudent function behaves like a factory. When other part of the program wants an instant of LocalStudent, it would give that instant. When the other part of the program wants an instant of OverseasStudent,it would get it. It could happen repeatedly on rest of the program.

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In this example, i used student scenario. Just assume we are developing an application for a school to record and process students registration. And the students are devided into 2 groups, local and overseas. Both share some similar properties such as student id and fullname. But both also have their own unique properties as you can see on picture 3 and 4.

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Student is our based class. It implements Print method from IPrint interface. It also holds common properties that are derived by LocalStudent and OverseasStudent.

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LocalStudent class its own unique property, BirthCertificateNo. In this scenario, when the school staff registers the new student,he/she must get the birthcertificate number from the candidate student if that person claims to be a local.

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If the candidate student is not from local, he/she must provides two informations : his/her country of origin and his/her passport number.

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Picture 5 shows Factory pattern from implementation perspective. Anytime we want to get any instant from both LocalStudent or OverseasStudent,we just need to pass in the corresponding parameter. Even, in the future if another group of student is created this pattern would serve well.

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Source

Creating Derived Class From LIST Generic Collection To Suit Your Need

2011-03-04T02:25:00.001-08:00

I like List so much because it is easy to be used. It has several very useful method such as Find method. This method allows us to find a specific item in the collection without the need to create a loop.

In this opportunity i want to create a derived class from List and gives some additional methods on it. To start ,we need to create a scenario. This example is about T Shirt. On picture 1 i have created a TShirt which contains several properties.

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Then i created a derived class. I named it MyList. As you can see on Picture 2, because List is a covariant class,so i declared MyList the same way, which is with suffix <T>. And because we are going to use this new collection class for TShirt objects only so we need additional information where <T>:TShirt at the end of the class declaration.This additional information will tell the compiler that our derived class only accept TShirt object on its operation.

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The next step, i added several new methods to suit my need which has not been provided by List,our base class. Picture 3 below,shows you my first method CountByColor. CountByColor is the method that will show the number of items in the collection that has a matching color with the given parameter. And there are other three new methods have been added. You can see them directly on my source code which you can download from the link i have provided at the bottom of this article.

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Picture 4 shows how to declare and use our new class. The same way when we use List.

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Picture 5 only shows part of Core.GetData function which is used to run my example here.

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Picture 6 is showing the output when the program was run.

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Source Code

Background Thread and Cross Control Invocation

2011-02-25T23:34:00.000-08:00

The biggest challenge when to develop windows form application is how to make the application stay responsive to user action and at the sametime it keeps processing the information. Just imagine you want to processing hundred thousands of record but at the same time you want other features on your application stays looks running such as the current time. Normally,the application will freeze all the controls on the windows form until it has completed the process. Event ,i don't think you would be able to stop the application in the middle of the process because the button on the form would not be clickable during that time. What you could do is going to the Task Manager and kill the program. That's not a professional way.

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In this opportunity i am going to show you how to use background thread to make my windows application stay responsive towards user action while it is still processing a huge amount of information.

Picture 1 shows you the look of the application before it is started. You can see the textbox down there showing current time and always changing. The start button is enabled and the stop button is disabled. I made those button interchangably enabled and disabled. If you click the start button, the start button would be set disabled and the stop button would be set enabled, vice versa.

Now i click the Start button. The application starts displaying a sequential numbers from 0 to 1 millions on the box on the left. As you can see on Picture 2, the application doesn't lose its responsiveness towards user action. If i click the Stop button the process will be stopped straight away,but the clock on the textbox is not interrupted at all.It keeps running as usual. Then if start again, the process will be resumed.

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In this application i am using BackgroundWorker from System.ComponentModel to create a new thread (Picture 3). But there is a problem. The thread that is created by BackgroundWorker class can not be stopped until it completes the whole working process.

So, i had an idea to create an inherited class to solve this problem. I named this class as Worker. There are 2 properties i added. One is IsStop and the other one is LastNumber. Property IsStop will be used to keep the state of the working process. And property LastNumber is to keep the next sequential number to run when the user click the start button again after the process being stopped.

I also added 2 public method,Start and Stop. Both method will be used by the calling application to stop or resume of the working process. As you can see on Picture 2, both methods simply just change the value of IsStop property from false to true,vice versa.

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Back to the application. The application initializes the inherited Worker object class on Page Load event (see Picture 6 and Picture 4).And also, there are 2 important events that will be set up.

First is DoWork event, which will be triggered by RunWorkerAsync() method. As you can see on Picture 2, this method will be run by Start public method. And Start method will be called as soon as the user click on Start button. When DoWork event is raised, it will make m_worker_DoWork method executed.

The second event is RunWorkerCompleted. This event is going to be triggered when the working process is finished doing its work.

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Because we create a new thread we have to be sure that when we access the controls on the form they are on the same thread, otherwise it would pop up an error. Fortunately, the controls have InvokeRequired property that will tell us if they are on the same thread or not with the method that is trying to access them. If that those controls are not on the same thread, we have to invoke the delegated functions and their values as seen on Picture 7.

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Publish Post

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Source

Drag and Drop With JQuery UI

2010-06-23T03:28:00.000-07:00

The more i use JQuery the more i love it. It makes my job easier to do some front end tricks. The following is about a simple game that let the user to drag the soccer balls on the left side into the bin on the right. Everytime the ball is successfully dropped into the bin, the number on the right will be increased by 1.

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The most important elements on the web form for this project relies on JQuery and JQuery-UI frameworks. Here we imports those frameworks on the fly from GOOGLE CDN website. So, make sure your computer is connected to the internet when the run this example.

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Between the BODY tag we declare images and labels.

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On SCRIPT section we attach the four soccer balls images to draggable function. And we also attach bin image to droppable function. When the drop event is triggered a function is executed. That function will change the visibility property of the dropped object to none. At the same time it will increase the counting and update the label.

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Source

Style Sheet On Silver Light

2010-06-19T03:23:00.001-07:00

On SilverLight, the style sheet is placed on an App.xaml file between Application.Resources tag.

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As you can see on picture 2, the way the style sheet is laid out is different compared with what we used to do on style sheet for a web form. There is an evolution.The style sheet syntax has been transformed into XML format. But some are still recognisable such as FontSize referring to font-size on style sheet on the web form.

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On the control, StaticResource keyword has to be called along side with the style name (picture 3).

Source C#
Source VB.NET

To Call WCF Service From Silver Light

2010-06-18T19:42:00.000-07:00

On your Visual Studio, click the File menu and select New Project.
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The window will show up.Select the programming language you want to use, select SilverLight and on the right window seelct SilverLight Application. Name your application MySilverLightApp. Click Ok.

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Another window appears, just click Ok.
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Now, on Solution Explorer double click on Page.xaml. Change the xaml code as seen on picture 4 below.

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After the changes have been done, you will see the new look.

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Select MySilverLightApp.Web project on your Solution Explorer. Right click and select Add then New Item.

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Select SilverLight enabled WCF Service, change the name of the new item to svcWCF.svc and click Add button.

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Now you see a new file under MySilverLightApp.Web (svcWCF.svc). Double click on it.

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Remove DoWork() method that was created automatically when you added that SilverLight enabled WCF service. And replace with the codes on picture 9.

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Select MySilverLightApp.Web project again, right click and select Set as StartUp project.

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Select svcWCF.svc file and set it up as Start up Page.

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Start Debugging,either by pressing F5 button or the green arrow button on the IDE. Soon, a window message will show up, just click Ok.

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The WCF service is running, ready to be consumed.

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Stop Debugging. As you can see on the right down corner of your task bar, there is a small icon remain stay there. The service is actually still running from the previous action.

Next, select your silverlight project, right click and select Add Service Reference.

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On popping up window, click Discover button. Because you just run one service on previous action, so there is only one url address on that combo box Address on the left. Change the NameSpace to clientWCFProxy. Click Ok.

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There are new files that have been added into your SilverLight project. They are clientWCFProxy and ServiceReferences.ClientConfig.

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Source C#
Source VB.NET

Web User Control

2010-06-06T21:56:00.000-07:00

There are several reason why we need to create web user controls. Some people said,it will improve the development time in the long run. In this scenario,if we are working on several project that require similar feature such as registration form, web user control would help us from redoing the same job again and again .

But others said this is just a matter of task delegation among programmers in the group. If we have several programmers in our team and we want devide the jobs more specific to them, ones probably would be suited for focusing their job in web user control development and the rest do other part of programming job.

In this opportunity i take an example of MJ Concert Registration Form. It requires the users to provide four basic information. There are three textboxes,one dropdown list.And there is a button to submit those information back to the server.

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After adding a web user control template into my project and designing the outlook, the next thing to do is to create a class that derives from System.EventArgs. This class is going to be used to contain the values entered by the user on my web user control and pass them on to page during the post back. In our case i have four properties on the class that are matched with the number of inputs appeared on my web user control.

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Then i need to declare a delegate function on my web user control . Basically a delegate function is almost similar to pointer in C++. Its duty is to encapsulate other function. In this scenario mine will encapsulate the external function, the function that is created on the web page.

Next one to declare is an event. Event is most likely a signal that is prepared to yield the system when certain condition has been reached. In my case the event has been wired to my delegate function. That means if that event is raised,automatically my delegate will be called. That call will make my delegate function executes the external function on the web page.

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After the users complete the necessary information, they have to press the submit button. When that happens the click event is triggered,all the information are kept in the object properties and passed on to the external function through delegate function.

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Picture 5 shows how web user control makes web page code looks simpler. Some complexity has been taken off into seperate module.

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When i was using C#, i couldn't find the way to create a function to be wired to my web user control automatically. On VB.NET it was easy. I just clicked the dropdown list on the IDE,select my web user control, select the desired event the second dropdown list and all the sudden the IDE created the function as required.

On C#, i wrote extra code on my source code. First step, i created the function by hand. That function has similar paramter that the delegate function has. Second step,on page load event i wired the submit event of my web user control to that function.

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Now i can do i like to do with the data that has been passed in to my function on my page.

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Source C#
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Using JQuery to Access WCF Services

2010-06-03T14:09:00.000-07:00

This article is about how to use JQuery to access WCF Services. Picture 1 shows on what it looks like. Everytime the user select different item on drop down list, the table will be refreshed with new information that correspond to that selected item.

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How does it do ? Simple. Everytime user select different item on the drop down list, that html control will raise change event. That event has been wired to a javascript function (picture 3). That function then calls JQuery AJAX function which post the selected item value to the WCF service. We can see the location of the WCF service on url property value.

Another important aspect to be remember is, if you send the parameter to WCF service through POST method, you need to put extra attribute on service contract as seen on picture 2. And because we choose JSON data format for communication between client javascript to WCF service, we need to declare JSON message format attribute as well.

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Picture 3 shows all property JQuery AJAX has. I compare this JQuery AJAX with the XMLHTTPRequest object, this is much better.

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The javascript function that does rendering receives the data in JSON format. Because most recent version of the browsers are able to detect JSON data type automatically, that data is transformed into objects. These objects will have the same structures with the objects returned by the WCF service. But if you are using older version of browser, you need to include JSON2.js into your web page and use it to convert JSON format data into compatible objects. You can get JSON2.js from www.json.org.

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When you download the source code and debug it, you can see that i used enumerator BookType. I wanted that BookType to be represented on the table in more readable form instead of numeric. So, i created an javascript variable array to hold every label of each enumerator item of BookType. The javascript function that renders the table (picture 4) pick one of the array by associating the array index to the book type value from the object . This process is done repeately from one row to the next.

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Source C#
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DataGrid Customization Part II

2010-05-25T16:57:00.001-07:00

In this opportunity i am about to customize my datagrid pager as seen on picture 1 below. Instead of using numerical links or back next button i prefer to use drop down list.It makes me feel easier to navigate through all the pages.

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Actually this pager customization is an enhancement of my previous article DataGrid Customization Part I
so i used the previous project with couple modifications. First modification is on Page PreRender event.
Here i declared a javascript variable to hold our datagrid id for later use.

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On DataGrid ItemCreated event , there is a condition if the item type is Pager then do the customization.

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Before the customization is started ,the existing default pager elements must be removed. Picture 4 shows how those elements are removed through loop process.

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Next step is to calculate number of pages based on various information gathered from datagrid and data feed.

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If there is only one page, the grid doesn't need to display any pager and its label. Otherwise the label and the dropdown list will be created on the fly.

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Other modification also need to be done on page Load event. It processes the parameter representing the selected page.

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The last thing to do is to attach the change event for the dropdown list. Here i used JQuery to find the dropdown list element on datagrid (remember the javascript variable i mentioned before) and do that attachment. Further information on how to use JQuery framework you can find it on www.jquery.com.
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Source C#
Source VB.NET

DataGrid Customization Part I

2010-05-20T04:18:00.001-07:00

Most people use Data Grid web control to show the information in table format as seen on picture 1. It allows the users to navigate the data from one page to the next easily. But what happen if you want different format but still taking the advantages of the data grid ?

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Just imagine that i want my video data to be displayed as shown on picture 2. Instead of placing my data in 5 different column, i just want to use two column. The first column is for the image and the second one holds the rest of the information.

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What i am doing here is just one way. You can try other way better than this when you have time. I created a new web project. I dragged datagrid web control from ToolBox on the default.aspx. Modify the HTML source code as you can see on picture 3 below. To customise the grid we need to use TemplateColumn. I added PlaceHolder web control that later would hold other web controls to be created on the fly.

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Now we need to create a class that is called Video as seen on picture 4.

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VB.NET

The next step is to create a function that return a collections of the available video. This is the function to feed our data grid data source.

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VB.NET

Data Grid can display the information in differrent pages. Everytime you select on of the element page, the Data Grid will raise the PageIndexChanged event. Feed you DataGrid source on this event as seen on picture 6. I used try and catch to anticipate the condition while you are clicking to the page which not longer exist because the data for that page has been deleted by other users.

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VB.NET

The real work is actually done on Data Grid event ItemDataBound. That is when the Data Grid trying to pass on each data chunk to the associated data fields on row by row basis.

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VB.NET

In my example i inserted Panel web control first as a canvas so i would be able to place the next web controls on precise positions to give a nice look. I just tried to avoid using Table. You can download the source codes from the link below and debug it by your self.

Source C#
Source VB.NET

XPath - Filtering Part II

2010-05-16T22:15:00.001-07:00

Quering in XPATH is as easy as in MS SQL. You can try "Select * from Books Where Publisher like '%Pelican%' and id > 500 " on SQL Statement turns to be "books/book[contains(publisher,'Pelican') and id > 500]" on XPath Expression.

The following below is the list of XPath string function you can try by your self :

concat()	concentrates two string values
contains()	Returns a Boolean value indicating whether the first value contains the second (true), or not (false)
normalize-space()	Leading and trailing spaces are removed from the value
starts-with()	Returns a Boolean value indicating whether the first value begins with the second value passed in
string()	Converts a value to a string
string-length()	Returns the length of a string value
substring()	Returns a portion of a string. The first parameter is the string, the second is the starting point of the substring, and the third parameter is the ending point of the substring returned.

Recommended Books:

XPath - Filtering Part I

2010-05-14T01:56:00.000-07:00

We can use XPath to filter the nodes that contain certain criterias. Just assume you a XML document as shown on picture .1. below. Then you only want to get the Book nodes which their id is greater than 300 and lower than 500. Picture .2. is showing the expression to do so.

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Recommended Books:

Navigating XML Nodes With XPATH

2010-05-12T21:59:00.000-07:00

XPath is an expression that is used to find parts in XML documents. Those parts are mostly nodes or node attributes. You can find more XPath definition on http://www.w3schools.com/xpath .

Just imagine someone give you a complex XML documents and you want to extract specific information from it. It would be easier for you to search specific information by using XPath instead of scanning all the nodes from the root down to next child nodes one by one. XPath will help to do that for you. What you need to do is giving it an expression parameter that shows hirarchy of the selected node you want to observe.

In this experiment i am going to use data from RSS Feed www.onenews.co.nz and save it as XML document in my project. Now i want to get all the title for each item, as you can see on below picture (within the red box).

picture .1. (click to enlarge)

We need to tell XPath the position of title on the XML document in hirarchical order. Picture .1. tell us that the title is under the item,item is under channel and channel is right under the rss (the root). Picture .2. shows how that information is passed.

picture .2.

You can download the provided source code. When you run it,the result would be seen on picture .3.

picture .3.

Source C#
Source VB.NET

Recommended Book :

WCF - The Simple Example Project

2010-05-12T04:17:00.000-07:00

Windows Communication Foundation or WCF has many similarities if we compare it with DCOM (Distributed Component Object Model) in 1998s. Both bring up the consept on how to distribute the process to other computers on the network and bring back the result of the operation to the calling computers. By this way the system is becoming more scalable to handle the rapid growing data to be processed.

But WCF is better off in term of how the data is formatted and transported. It starts with TCP/IP, MSMQ,FTP and the Name Pipe. And it uses XML as a document format for data exchange, in which also can be digested easly by non Microsoft platform such Java. And the main element that elivitates WCF on the horizon is the IIS.Even though you still can run WCF as part of MS Windows Services but most people run their WCF on IIS as services.

The Database

To run the example you need to download the database first and attach that database to your local MSSQL Server. In this case i was using MSSQL Express 2005. This database contains Book table and several stored procedures.

picture .1.

After you attach your database, you need to modify the connection string on the web config. You need to change to server name according to yours. In my case i used LivingSuburb as my server name.

picture .2. (click to enlarge)

The Server Host

Now it is time to open the host project with Visual Studio and run it.

picture .3.

The Client

to insert
picture .3.

to update

picture .4.

to show all the record

picture .5.

to read a specific record

picture .6.

Server Host C# Client Application C#
Server Host VB.NET Client Application VB.NET
Database

Recommended Book :

Keeping Your Web Application Active

2010-04-30T02:36:00.000-07:00

I had a personal bad experience with web hosting company. It seemed like they had set up their web servers to terminate any web application that was idle around 1 minute. That caused problem with my site. Because my site is new and only few user came to visit so every user experienced a long delay as the IIS recompiled my web application all over again.

It made me think on how to keep my web application looks actively accessed by many users. Then i made this KeepAlive console application. It is easy to be used and very light.

Source Code C#

Simulating SQL Query SELECT IN on LINQ

2010-04-18T18:43:00.000-07:00

We have a student table. It contains 7 records. Now we intend to use the SELECT IN statement to get records with id 2,5 and 7.

select * from student where id in (2,5,7)

And the result is :

We can do similar query on LINQ. First i need to create an Object that has similar properties as the Student table has.

Second step is to create a list of Student that contains 7 records to mimic the same values as shown on Student table.

Third, we create another List that holds the selected id we about to retrieve.

Fourth, we construct the LINQ query , join the two list but only select from the first like everything that their id are match with the id of the second list.

Fifth, simply just to prove the result.

Source Code - C#
Source Code - VB.NET