how to write custom dbcontext

Question

I am trying to learn MVC 3/4 using visual studio 2012. I have created a view, a model and controller. VS created all the database stuff for me. It added a gridview for me where I can add a new row, edit or delete too. I would like to change the way it selects the rows from the database. I know that I have to change the DbContext for that.

here is my DbContext,

public class ApartmentContext : DbContext
{

    public ApartmentContext() : base("name=ApartmentContext")
    {
    }

    // this part has to be changed****
    public DbSet<Apartment> Apartments { get; set; } 
}

public DbSet Apartments{...} returns the list I guess, but I want to change the way it selects the rows. For example; I want to select the rows whose "flag" column is set to 1. how do I do that?

thanks

Amin Saqi · Accepted Answer · 2013-05-30 07:45:48Z

2

You should filter your results in the related controller, not in the DbContext. It could be like this in that controller:

...
ApartmentContext db = new ApartmentContext();
var apartments = db.Apartments.Where(a => a.Flag == 1);
...

and then use apartment object to render your view

answered May 30, 2013 at 7:45

Amin Saqi

19.1k9 gold badges53 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Piotr Stapp Over a year ago

You should create database context in using statement or dispose it manually. Without this you could have memory leaks

Piotr Stapp · Accepted Answer · 2013-05-30 07:41:36Z

1

You need to create query. Object Apartments represents table in database, not a list.

answered May 30, 2013 at 7:41

Piotr Stapp

19.9k11 gold badges72 silver badges118 bronze badges

Comments

Jalpesh Vadgama · Accepted Answer · 2013-05-30 08:24:02Z

0

You can also use entity framework dbconext to execute your TSQL Statement or stored procedure. Following is a link for that.

http://www.dotnetjalps.com/2012/04/execute-tsql-statement-with.html

answered May 30, 2013 at 8:24

Jalpesh Vadgama

14.4k21 gold badges75 silver badges95 bronze badges

Comments

Dominic Zukiewicz · Accepted Answer · 2013-05-30 13:04:41Z

An alternative is to have a wrapping interface around the context to hide these details, so that is applies to every query transparently:

// Wrapping interface
public interface IApartmentRepository
{
    IQueryable<Apartment> Apartments { get; }
}

// As before
public class ApartmentContext : DbContext
{
  ...
}

// Implementing class, hiding the DbContext object
public class EFApartmentRepository : IApartmentRepository
{
   private ApartmentContext context = new ApartmentContext();

   public IQueryable<Apartment> Apartments
   {
       get { return this.context.Apartments.Where(a => a.Flag == 1); }
   }
}

// Your controller uses DI to get the controller
public class HomeController : Controller
{
   private IApartmentRepository apartmentContext;

   public HomeController( IApartmentRepository rep )
   {
      this.apartmentContext = rep;
   }
}

The controllers IApartmentRepository parameter can be hooked up to the EFApartmentRepository by overidding the DefaultControllerFactory class. You use a DI framework like NInject or StructureMap to insert the correct implementation into the constructor at runtime.

Collectives™ on Stack Overflow

how to write custom dbcontext

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related