About DbContext in the EF Entity Framework

EF4.1 includes code first and DbContext APIs. The DbContext API provides more ways for EF to work: Code First,database First and model first.

Using the DbContext constructor

1. Code First Contract connection

Namespace Magic.unicorn
{
public class Unicornscontext:dbcontext
{
Public Unicornscontext ()
C # would call base class parameterless constructor by default
{
}
}
}

The connection string (SQL Express) for the database is generated on this computer using Magic.Unicorn.UnicornsContext as the database name.

2. Code first specifies the contract connection for the database name

public class Unicornscontext:dbcontext
{
Public Unicornscontext ()
: Base ("Unicornsdatabase")
{
}
}

The connection string (SQL Express) for the database is generated on this computer using Unicornsdatabase as the database name.

3. Code first uses the connection string in the configuration file

<connectionStrings>
<add name= "Unicornscedatabase"
Providername= "system.data.sqlserverce.4.0"
connectionstring= "Data source=unicorns.sdf"/>
</connectionStrings>

public class Unicornscontext:dbcontext
{
Public Unicornscontext ()
: Base ("Name=unicornscedatabase")
{
}
}

4. Database/model connection characters in the config file for first use

<add name= "Northwind_entities"
Connectionstring= "
metadata=res://*/northwind.csdl|
res://*/northwind.ssdl|
RES://*/NORTHWIND.MSL;
Provider=system.data.sqlclient;
Provider Connection string=
&quot;data source=.\sqlexpress;
Initial Catalog=northwind;
Integrated security=true;
multipleactiveresultsets=true&quot; "
Providername= "System.Data.EntityClient"/>

public class Northwindcontext:dbcontext
{
Public Northwindcontext ()
: Base ("Name=northwind_entities")
{
}
}

About DbContext in the EF Entity Framework