How to Ignore Properties in Entity Framework Code First?

Properties ignored in Entity Framework 4.1 Code First

In Entity Framework (EF) 4.1 Code First, it is possible to exclude certain properties from database mapping using the [NotMapped] property data annotation. This annotation applies to the corresponding property in the entity class.

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

The

[NotMapped] attribute is part of the System.ComponentModel.DataAnnotations namespace.

Also, you can use the Fluent API to override the OnModelCreating function in the DbContext class.

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

Please note that the EF version suggested in the original question is outdated. The latest stable version as of NuGet is EF 4.3.

Update (September 2017): Asp.NET Core (2.0)

For Asp.NET Core 2.0 and above, you can use the previously mentioned [NotMapped] attribute. In addition, the Fluent API can be used as follows:

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; }
}

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