Linq to SQL Mapping by decorating classes with special attributes

With LINQ to SQL, you can set up mappings between C# classes and an implied database schema either

by decorating the classes with special attributes or by writing an XML.

Following is a c# 4.0 code that describes first approach i.e. Linq to Sql mapping by decorating classes with special attributes.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Data.Linq.Mapping;

using System.Data.Linq;

[Table(Name="Jobs")] public class Job

{

[Column(IsPrimaryKey=true, IsDbGenerated=true, AutoSync=AutoSync.OnInsert)]

internal int JobID { get; set; }

[Column] public string JobTitle { get; set; }

[Column] public long Salary { get; set; }

}

[Table(Name="Applications")] public class Application

{

[Column(IsPrimaryKey=true, IsDbGenerated=true, AutoSync=AutoSync.OnInsert)]

internal int ApplicationID { get; set; }

[Column] public int JobID  { get; set; }

[Column] public DateTime DateApplied { get; set; }

}

String ConStr=”"Data Source=localhost;Initial Catalog=JobsDB;Integrated Security=SSPI;"

DataContext dc = new DataContext(connectionString); // Get a live DataContext

dc.GetTable<Job>(); // Tells dc it's responsible for persisting the class Job

dc.GetTable<Application>(); // Tells dc it's responsible for persisting the class Application

dc.CreateDatabase(); // Causes dc to issue CREATE TABLE commands for each class

Above code will create JobsDB along with tables Jobs and Applications.

SilverLight - Fill a ComboBox

Just doing some test

Binding a ComboBox at runtime.

private void button1_Click(object sender, RoutedEventArgs e)

{

List<Car> carList = new List<Car>();

carList.Add(new Car() { Name = "Ferrari", Price = 150000 });

carList.Add(new Car() { Name = "Honda", Price = 12500 });

carList.Add(new Car() { Name = "Toyota", Price = 11500 });

comboBox1.ItemsSource = carList;

comboBox1.DisplayMemberPath = "Name";

comboBox1.SelectedIndex = 2;

comboBox1.SelectionChanged += new SelectionChangedEventHandler(comboBox1_SelectionChanged);

}

void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)

{

Car selCar =(Car) comboBox1.SelectedItem;

MessageBox.Show(selCar.Name);

}

}

public class Car

{

public string Name { get; set; }

public int Price { get; set; }

}

Binding a ComboBox at design time;
<ComboBox Height="23" HorizontalAlignment="Left" Margin="225,184,0,0" Name="comboBox2" VerticalAlignment="Top" Width="120" ItemsSource="{Binding}" >

            <ComboBoxItem Content="Value-1"></ComboBoxItem>

            <ComboBoxItem Content="Value-2"></ComboBoxItem>

            <ComboBoxItem Content="Value-3"></ComboBoxItem>

            <ComboBoxItem Content="Value-4"></ComboBoxItem>

            <ComboBoxItem Content="Value-5"></ComboBoxItem>

</ComboBox>

TripleDES Encryption using MD5 Hashing

Example in VB.Net

Imports System.IO
Imports System.Text
Imports System.Security.Cryptography　
Public NotInheritable Class Utility
 Private Sub New()
End Sub

Private Shared Function CreateDES(ByVal key As String) As TripleDESDim md5 As MD5 = New MD5CryptoServiceProvider()
Dim des As TripleDES = New TripleDESCryptoServiceProvider()
des.Key = md5.ComputeHash(Encoding.Unicode.GetBytes(key))
des.IV = New Byte(des.BlockSize \ 8 - 1) {}
Return des
End Function

Public Shared Function Encryption(ByVal PlainText As String, ByVal key As String) As String
Dim des As TripleDES = CreateDES(key)
Dim ct As ICryptoTransform = des.CreateEncryptor()
Dim input As Byte() = Encoding.Unicode.GetBytes(PlainText)
Return Convert.ToBase64String(ct.TransformFinalBlock(input, 0, input.Length))
End Function

Public Shared Function Decryption(ByVal CypherText As String, ByVal key As String) As String
Dim b As Byte() = Convert.FromBase64String(CypherText)
Dim des As TripleDES = CreateDES(key)
Dim ct As ICryptoTransform = des.CreateDecryptor()
Dim output As Byte() = ct.TransformFinalBlock(b, 0, b.Length)
Return Encoding.Unicode.GetString(output)
End Function

End Class

 Example:
Dim strEncrypted As String = Utility.Encryption("Hello", "TESTKEY3327ABC09876433")
Dim strDecrypted As String = Utility.Decryption(strEncrypted,TESTKEY3327ABC09876433")MessageBox.Show(strDecrypted)

Code Contracts in .NET 4

Reference : http://visualstudiomagazine.com/articles/2010/06/23/code-contracts.aspx
http://www.codeproject.com/KB/cs/CodeContracts.aspx

One of the key features of the .NET Framework is its enforcement of strong typing. But sometimes, simply enforcing that an integer is passed into a method isn't enough. We have to write additional code to make sure the integer is in a particular range or some other requirement. With Code Contracts, we get a language-neutral way to express such additional requirements in the form of preconditions, postconditions and invariants.

What is Code Contracts
Code Contracts is a subset of a larger Microsoft Research Project called Spec# (pronounced "Spec Sharp"). You can read more about this project here. Spec# is a formal language for defining API contracts. A subset of these contracts -- preconditions, postconditions and invariants -- has made its way into Visual Studio 2010 in the form of Code Contracts.

Before being able to utilize Code Contracts, you'll need to download and install it from http://msdn.microsoft.com/en-us/devlabs/dd491992.aspx. Why the need for the download? Code Contracts has support for both Visual Studio 2008 as well as 2010. Since it's not a VS 2010-specific product, a separate download is required.

Example :

using System.Diagnostics.Contracts;

public class TestContract

    {

        int m_n1;

        int m_n2;

        public TestContract(int x,int y)

        {

            Contract.Requires(x > 10, "x should be > 10");

            m_n1 = x;

            m_n2 = y;

        }       

    }

Now try to create an object of TestContract

                TestContract obj = new TestContract(3, 20);

This will throw exception as “x should be > 10”

Parallel Programming with dot net

http://msdn.microsoft.com/en-us/library/ff963553.aspx

Example.
using System.Threading.Tasks;
int n=5;
Parallel.For(0, n, i => {
MessageBox.Show(i.ToString());
});

Razor Template Engine

Razor Code can be parsed using Razor template engine. http://razorengine.codeplex.com/
Following sample demonstrate how to achieve that.  Both @function and @helper are working.

SIMPLE TEMPLATE

string template = "Hello @Model.Name! Welcome to Razor!";

            string result = Razor.Parse(template, new { Name = "World" });

            MessageBox.Show(result);

@FUNCTION

string template = "@functions{ public static string RenderDiscountedPrice(decimal price){    return \"Buy now for only 10 with $1.00 off!\";}}  @RenderDiscountedPrice(10);"; // WORKS

            string result = Razor.Parse(template,null);

            MessageBox.Show(result);

@HELPER

string template = "@helper RenderDiscountedPrice(decimal price){ \"Buy now for only 10 with $1.00 off!\";} Hello @RenderDiscountedPrice(10);"; // WORKS

            string result = Razor.Parse(template,null);

            MessageBox.Show(result);

MODEL

string template = "Users List :\n @foreach(var e in Model){\n  @e.Name  @e.Designation  }";       // WORKS

                var f = new FakeEmployeesRepository();

                string result = Razor.Parse(template, f.Employees);

                MessageBox.Show(result);

Where Employees Model is as follows;

public class Employee

       {

              public int EmployeeCode { get; set; }

              public string Name { get; set; }

              public string Designation { get; set; }

       }

public class FakeEmployeesRepository : IEmployeesRepository

       {

              // Hard Coded list of employees

              private static readonly IQueryable<Employee> _fakeEmployees = new List<Employee> {

        new Employee {EmployeeCode=1,  Name = "Imran", Designation="Senior Software Engineer"},

        new Employee {EmployeeCode=2,  Name = "Andrew", Designation="Graphic Designer"},

        new Employee {EmployeeCode=3,  Name = "Michael", Designation="Project Manager"},

        new Employee {EmployeeCode=4,  Name = "John", Designation="Database Administrator" },

        new Employee {EmployeeCode=5,  Name = "Robert", Designation="Project Director"}

        }.AsQueryable();

              public IQueryable<Employee> Employees

              {

                     get { return _fakeEmployees; }

              }

       }

MVC response caching

An MVC response can be cached on client side using [OutputCache].

e.g.

public class UserController : Controller

{

[OutputCache(Duration = 60, VaryByParam = "None")] // Duration in seconds

public ActionResult List()

{

try

{

UserCache objUsers = new UserCache();

return View(objUsers.GetUsersList());

}

catch (Exception ex)

{

throw ex;

}

}

}