mapping private property entity framework code first

you can't map private properties in EF code first. You can try it changing it in to protected and configuring it in a class inherited from EntityConfiguration .
Edit
Now it is changed , See this https://stackoverflow.com/a/13810766/861716

Try this.

  public class UserAccount
    { 
       private string Username { get; set;}
    }



   public class UserAccountConfiguration :IEntityTypeConfiguration<UserAccount>
     {
       public void Configure(EntityTypeBuilder<UserAccount> builder)
         {
           builder.Property(c => c.Username);
         }
}

and then in DbContext

protected override void OnModelCreating(ModelBuilder modelBuilder)
  {
    modelBuilder.ApplyConfiguration(new UserAccount.UserAccountConfiguration());
  }

Another workaround might be to set your field as internal:

    [NotMapped]
    public dynamic FacebookMetadata {
        get
        {
            return JObject.Parse(this.FacebookMetadataDb);
        }
        set
        {
            this.FacebookMetadataDb = JsonConvert.SerializeObject(value);
        }
    }

    ///this one
    internal string FacebookMetadataDb { get; set; }

and add it to tour model:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove<System.Data.Entity.ModelConfiguration.Conventions.ManyToManyCascadeDeleteConvention>();

        ///here
        modelBuilder.Entity<FacebookPage>().Property(p => p.FacebookMetadataDb);

        base.OnModelCreating(modelBuilder);
    }

Here's a convention you can use in EF 6+ to map selected non-public properties (just add the [Column] attribute to a property).

In your case, you'd change TypeId to:

    [Column]
    private int TypeId { get; set; }

In your DbContext.OnModelCreating, you'll need to register the convention:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Add(new NonPublicColumnAttributeConvention());
    }

Finally, here's the convention:

/// <summary>
/// Convention to support binding private or protected properties to EF columns.
/// </summary>
public sealed class NonPublicColumnAttributeConvention : Convention
{

    public NonPublicColumnAttributeConvention()
    {
        Types().Having(NonPublicProperties)
               .Configure((config, properties) =>
                          {
                              foreach (PropertyInfo prop in properties)
                              {
                                  config.Property(prop);
                              }
                          });
    }

    private IEnumerable<PropertyInfo> NonPublicProperties(Type type)
    {
        var matchingProperties = type.GetProperties(BindingFlags.SetProperty | BindingFlags.GetProperty | BindingFlags.NonPublic | BindingFlags.Instance)
                                     .Where(propInfo => propInfo.GetCustomAttributes(typeof(ColumnAttribute), true).Length > 0)
                                     .ToArray();
        return matchingProperties.Length == 0 ? null : matchingProperties;
    }
}