When we start a
work on an application we spent most of
time to create database and tables but in entity framework there is advantages that it automatically create, update and drop databases when the
application runs.
EF suggest to use
'Database Migrations' to prevent from loosing Database or Records. Mostly we do not use 'Database Migrations' in our normal
application and for this EF got Database 'Seed' Method this allow you to seed some dummy data in the
database for testing purpose and this could be used in our applications like MVC, ASP.NET, Windows Form apps etc.
To seed data into database, you have to create custom
DB initializer,
·
DropCreateDatabaseIfModelChanges<DBContext>
·
CreateDatabaseIfNotExists<DBContext>
·
DropCreateDatabaseAlways<DBContext>
Now we will create a application with seed method.
Step(1) : create a new project
Open visual studio -> click new project -> Visual
C# - > WindowsFormsApplication1.
Step(2) : First
of create this application install Entity framework, process of installing
Entity framework i shown you before tutorial throw “ nuget package manager”
Step(4) : Add
a class for Student for defining parameters.
Right click on the solution explorer and add a class and define
attribute in this class using code first approach.
using System;
using
System.Collections.Generic;
using System.Linq;
using System.Text;
using
System.Threading.Tasks;
namespace
WindowsFormsApplication1
{
class Student
{
public int StudentId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
}
Step(5) : Add
a another class for StudentEntity for
defining DbContext.
using System;
using
System.Collections.Generic;
using System.Linq;
using System.Text;
using
System.Threading.Tasks;
using System.Data.Entity;
namespace
WindowsFormsApplication1
{
class studentEntity : DbContext
{
public DbSet<Student> Students { get; set; }
}
}
Here we have
to remember that we have to use ‘using System.Data.Entity; namespace.
Step(6) : Database Initializer
Add a new class For Database initialize Now put the data for showing when
database first created.
using System;
using
System.Collections.Generic;
using System.Linq;
using System.Text;
using
System.Threading.Tasks;
using System.Data.Entity;
namespace
WindowsFormsApplication1
{
class StudentDataBaseInitializer : DropCreateDatabaseIfModelChanges<studentEntity>
{
protected override void Seed(studentEntity context)
{
var students = new List<Student>
{
new Student { FirstName = "Munesh", LastName = "Sharma" },
new Student { FirstName = "Vinod", LastName = "Roy" },
new Student { FirstName = "Manish
",
LastName = "Kumar"
},
new Student { FirstName = "Rohit ", LastName = "jash" },
new Student { FirstName = "gautam", LastName = "shree" }
};
students.ForEach(s =>
context.Students.Add(s));
context.SaveChanges();
}
}
}
Step(7) : Seed Data to Database
We use this line for Seed the data into database
Database.SetInitializer<studentEntity>(new
StudentDataBaseInitializer());
Step(8) :
show in form
Add a Form and take a button and write the below code
on button click
using System;
using
System.Collections.Generic;
using
System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using
System.Threading.Tasks;
using
System.Windows.Forms;
using System.Data.Entity;
namespace
WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
using (var context = new studentEntity())
{
Database.SetInitializer<studentEntity>(new StudentDataBaseInitializer());
//This is linq query
var stdInfo = (from C in context.Students
select new { Id = C.StudentId,
FirstName = C.FirstName });
foreach (var info in stdInfo)
{
Console.WriteLine("ID : " + info.Id + ", Name :
"
+ info.FirstName);
}
Console.ReadKey();
}
}
}
}
After click on button you will see the result with FirstName and LastName.
