2.
Create the Model
Now
we will create two simple model(Employee, Manager) using classes. As
a part of demo I'll define both in Program.cs but in a real word
application we should define in two separate file/classes.
Add
the following two classes in Program.cs.
public
class
Manager
{
public
int
ManagerId { get;
set;
}
public
int
ManagerName { get;
set;
}
public
virtual
List<Employee>
Employees { get;
set;
}
}
public
class
Employee
{
public
int
EmployeeId { get;
set;
}
public
String
EmployeeName { get;set;
}
public
String
EmployeeDesignation { get;
set;
}
public
int
ManagerId {get;set;}
public
virtual
Manager
Manager { get;
set;
}
}
If
you have notice I have made the two navigation properties
(Manager.Employee and Employee.Manager) virtual. This enables the
Lazy Loading feature of Entity Framework. Lazy Loading means that the
contents of these properties will be automatically loaded from the
database when you try to access them.
3.
Create a Context
Before
creating a context, first we will install the EntityFramework Nuget
package.
Now
we need to create a session so that we can query and save data into
the database, we need to define a derived context
(System.Data.Entity.DbContext) and exposes a typed DbSet<Entity>
for each class in our model.
Add
following derived context in the the Program.cs file.
public
class
ManagingContext
: DbContext
{
public
DbSet<Manager>
Blogs { get;
set;
}
public
DbSet<Employee>
Posts { get;
set;
}
}
Program.cs
:
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
using
System.Data.Entity;
namespace CreateNewDatabase
{
class Program
{
static void Main(string[] args)
{
}
}
public class Manager
{
public int ManagerId { get; set; }
public String ManagerName { get; set; }
public String ManagerAddress { get; set; }
public virtual List<Employee> Employees { get; set; }
}
public class Employee
{
public int EmployeeId { get; set; }
public String EmployeeName { get;set; }
public String EmployeeDesignation { get; set; }
public int ManagerId {get;set;}
public virtual Manager Manager { get; set; }
}
public class ManagingContext : DbContext
{
public DbSet<Manager> Managers { get; set; }
public DbSet<Employee> Employees { get; set; }
}
}
4.
Reading and Writing Data
Now
its the time to implement the Main method in Program.cs. It will
create a new instance of our context and then uses it to insert a new
Manager. I have used LINQ query to retrieve all Manager entry from
the database.
class
Program
{
static
void
Main(string[]
args)
{
using
(var
db = new
ManagingContext())
{
//
Create and save a new Manager entry
Console.Write("Enter
a name for a new Manager: ");
var
name = Console.ReadLine();
var
manager = new
Manager
{ ManagerName = name };
db.Managers.Add(manager);
db.SaveChanges();
//
Display all Managers from the database
var
query = from
b in
db.Managers
orderby
b.ManagerName
select
b;
Console.WriteLine("All
Managers in the database:");
foreach
(var
item in
query)
{
Console.WriteLine(item.ManagerName);
}
Console.WriteLine("Press
any key to exit...");
Console.ReadKey();
}
}
}
Now
Run the Application :
