Ignoring a class property in Entity Framework 4.1 Code First

Question

My understanding is that the [NotMapped] attribute is not available until EF 5 which is currently in CTP so we cannot use it in production.

How can I mark properties in EF 4.1 to be ignored?

UPDATE: I noticed something else strange. I got the [NotMapped] attribute to work but for some reason, EF 4.1 still creates a column named Disposed in the database even though the public bool Disposed { get; private set; } is marked with [NotMapped]. The class implements IDisposeable of course but I don't see how that should matter. Any thoughts?

Answer 1

You can use the NotMapped attribute data annotation to instruct Code-First to exclude a particular property

public class Customer {     public int CustomerID { set; get; }     public string FirstName { set; get; }      public string LastName{ set; get; }      [NotMapped]     public int Age { set; get; } } 

[NotMapped] attribute is included in the System.ComponentModel.DataAnnotations namespace.

You can alternatively do this with Fluent API overriding OnModelCreating function in your DBContext class:

protected override void OnModelCreating(DbModelBuilder modelBuilder) {    modelBuilder.Entity<Customer>().Ignore(t => t.LastName);    base.OnModelCreating(modelBuilder); } 

http://msdn.microsoft.com/en-us/library/hh295847(v=vs.103).aspx

The version I checked is EF 4.3, which is the latest stable version available when you use NuGet.

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Edit : SEP 2017

Asp.NET Core(2.0)

Data annotation

If you are using asp.net core (2.0 at the time of this writing), The [NotMapped] attribute can be used on the property level.

public class Customer {     public int Id { set; get; }     public string FirstName { set; get; }      public string LastName { set; get; }      [NotMapped]     public int FullName { set; get; } } 

Fluent API

public class SchoolContext : DbContext {     public SchoolContext(DbContextOptions<SchoolContext> options) : base(options)     {     }     protected override void OnModelCreating(ModelBuilder modelBuilder)     {         modelBuilder.Entity<Customer>().Ignore(t => t.FullName);         base.OnModelCreating(modelBuilder);     }     public DbSet<Customer> Customers { get; set; } }