Entity Framework resources and suggestion - entity-framework

Question

Last few weeks I have been learning entity Framework, had exposure to ADO.Net and some LINQ syntax. I am basically finding so much setup and wiring to do before you can actually get into the developing the stuffs. I am especially having hard time in Code First approach, have also spent sometime in passionate blogs of Julie Larnam. Any suggestions on books, articles or blogs on entity framework to expedite my learning and deeper understanding would be appreciated.
Thanks
Alaxi

Answer 1

Initialization
Step one, setup your models
public class Person
{
public Int32 Id { get; set; }
public String Name { get; set; }
public String Email { get; set; }
// one-to-many relationship to Pet (EF picks up on this automatically)
public ICollection<Pet> Pets { get; set; }
}
public class Pet
{
public Int32 Id { get; set; }
public String Name { get; set; }
public String Breed { get; set; }
// foreign key back to person (EF picks up on this automatically)
public Person Owner { get; set; }
}
Step two, create a context using your models
public MyContext : DbContext
{
public DbSet<Person> Persons { get; set; }
public DbSet<Pet> Pets { get; set; }
}
Step three, create a connectionString
protip: The name of the connection string should match that of your context.
<connectionStrings>
<add name="MyContext"
providerName="System.Data.SqlClient"
connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=MyContext;IntegratedSecurity=True;" />
</connectionStrings>
Run through
Basic
// automatically find the connection string matching the context name,
// as well as performs a check to see if:
// 1. The database exists
// 2. The schema is up-to-date
MyContext context = new MyContext();
context.Persons.Add(new Person {
Name = "Brad Christie",
Email = "bchristie#contoso.com"
});
context.SaveChanges();
Intermediate
You can also change how the data is generated using Initializers. For example, if you wanted to pre-populate the database with information you can do the following:
public class MyContextInitializer
// this could be `DropCreateDatabaseAlways<TContext> or any other
// preexsting initializer:
: DropCreateDatabaseIfModelChanges<MyContext>
// you can also create your own explicitly if you implement the
// following interface, but that's a bit much starting out.
//: IDatabaseInitializer<MyContext>
{
protected override void Seed(MyContext context)
{
new List<Person> {
new Person {
Name = "Brad Christie",
Email = "bchristie#contoso.com",
Pets = new HashSet<Pet> {
new Pet {
Name = "Spot",
Breed = "Dalmation"
}
}
}, new Person {
Name = "Alaxi04",
Email = "Alaxi04#contoso.com",
Pets = new HashSet<Pet> {
new Pet {
Name = "Petey",
Breed = "Parrot"
}
}
}
}.ForEach(p => context.Persons.Add(p));
base.Seed(context);
}
}
In practice:
// call this somewhere early on in the application (but only once!)
Database.SetInitializer<MyContext>(new MyContextInitializer());
// This can also be configured through the `web.config`:
<entityFramework>
<contexts>
<context type="MyNamespace.MyContext, MyAssembly">
<databaseInitializer type="MyNamespace.MyContextInitializer, MyAssembly" />
</context>
</contexts>
</entityFramework>
/* ***** */
// then use the context as normal:
MyContext context = new MyContext();
var petOwners = context.Persons.AsEnumerable();