Delete Data Using Silverlight RIA Enabled Service

Introduction

Today, in this article let's play around with one of the interesting and most useful concepts in Silverlight.

Question: What is delete data using a Silverlight RIA enabled service?

In simple terms "This application enables deletion of data in the database with the help of a Silverlight RIA enabled service. It uses a base platform of entity framework to communicate with the database".

Step 1: Create a database named "Company" with employee table in it.

Step 2: Open Visual Studio and create a new Silverlight application enabled with RIA Services

Step 3: When the project is created, right-click on the RIA Service project and add a new entity data model framework and set it up for a previously created database.

Step 4: Again right-click on the RIA service project and add a Domain Service Class as a new item.

Step 5: The complete code of EmployeeDomain.cs looks like this (Domain Service Class):

namespace SilverlightRIAInsert.Web

{

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.ComponentModel.DataAnnotations;

using System.Data;

using System.Linq;

using System.ServiceModel.DomainServices.EntityFramework;

using System.ServiceModel.DomainServices.Hosting;

using System.ServiceModel.DomainServices.Server;

// Implements application logic using the CompanyEntities context.

// TODO: Add your application logic to these methods or in additional methods.

// TODO: Wire up authentication (Windows/ASP.NET Forms) and uncomment the following to disable anonymous access

// Also consider adding roles to restrict access as appropriate.

// [RequiresAuthentication][EnableClientAccess()]

public class EmployeeDomain : LinqToEntitiesDomainService<CompanyEntities>

{

// TODO:// Consider constraining the results of your query method. If you need additional input you can

// add parameters to this method or create additional query methods with different names.

// To support paging you will need to add ordering to the 'Employee'

query.public IQueryable<Employee> GetEmployee()

{

return this.ObjectContext.Employee;

}

public void InsertEmployee(Employee employee)

{

if ((employee.EntityState != EntityState.Detached))

{

this.ObjectContext.ObjectStateManager.ChangeObjectState(employee, EntityState.Added);

}

else

{

this.ObjectContext.Employee.AddObject(employee);

}

public void UpdateEmployee(Employee currentEmployee)

{

this.ObjectContext.Employee.AttachAsModified(currentEmployee, this.ChangeSet.GetOriginal(currentEmployee));

}

public void DeleteEmployee(Employee employee)

{

if ((employee.EntityState != EntityState.Detached))

{

this.ObjectContext.ObjectStateManager.ChangeObjectState(employee, EntityState.Deleted);

}

else

{

this.ObjectContext.Employee.Attach(employee);

this.ObjectContext.Employee.DeleteObject(employee);

}

Step 6: Now rebuild the solution file.

Step 7: The complete code of MainPage.xaml looks like this:

<usercontrolx:class="SilverlightRIAInsert.MainPage"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"mc:ignorable="d"
d:designheight="300"d:designwidth="543">
<Gridx:Name="LayoutRoot"Width="608">
<TextBlockHeight="23"HorizontalAlignment="Left"Margin="152,29,0,0"Name="textBlock1"Text="Id"FontFamily="Verdana"FontSize="15"VerticalAlignment="Top"/>
<TextBoxHeight="23"HorizontalAlignment="Left"Margin="252,25,0,0"Name="textBox1"VerticalAlignment="Top"Width="120"/>
<ButtonContent="Delete"FontFamily="Verdana"FontSize="19"Background="DeepSkyBlue"Height="44"HorizontalAlignment="Left"Margin="252,67,0,0"Name="button1"VerticalAlignment="Top"Width="120"Click="button1_Click"/>
</Grid>
</usercontrol>

Step 8: The complete code of MainPage.xaml.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Net;

using System.ServiceModel.DomainServices.Client;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Shapes;

using SilverlightRIADelete.Web;

namespace SilverlightRIADelete

{

public partial class MainPage : UserControl

{

public MainPage()

{

InitializeComponent();

}

EmployeeDomain objDomain = new EmployeeDomain();

private void button1_Click(object sender, RoutedEventArgs e)

{

EntityQuery<Employee> query = objDomain.GetEmployeeQuery();

objDomain.Load(query, DeleteLoad, null);

MessageBox.Show("Data Deleted Successfully");

}

public void DeleteLoad(LoadOperation<Employee> emp)

{

foreach (Employee e in objDomain.Employees)

{

if (e.Id == int.Parse(textBox1.Text))

{ objDomain.Employees.Remove(e);

objDomain.SubmitChanges(); break;

}

textBox1.Text = string.Empty;

}

Step 9: The output of the application looks like this:

Step 10: Data entering output of application looks like this:

Step 11: Data deleted output of the application looks like this:

I hope this article is useful for you.