How to set a string-like field to nullable in Code First?

Question

I got the field descrPapel of the kind string and would like that field to be created as nullable, that is, to accept null when I was gonna do some Insert/update in records of this type of entity.

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace Modelo.Classes.Banco
{
    public class Papeis
    {
        [Key]
        public Int32 idpapel { get; set; }
        [Required, MaxLength(100)]
        public string nomePapel { get; set; }
        [Required,MaxLength(200)]
        public string descrPapel { get; set; }
        public DateTime dtInclusao { get; set; }

        public virtual ICollection<PapeisUsuario> PapeisUsuario  { get; set; }
    }
}

The form the field is created to not accept values null to that field [descrPapel] [nvarchar](200) NOT NULL,;

See how it was created by the Entity Framework:

CREATE TABLE [dbo].[Papeis](
    [idpapel] [int] IDENTITY(1,1) NOT NULL,
    [nomePapel] [nvarchar](100) NOT NULL,
    [descrPapel] [nvarchar](200) NOT NULL,
    [dtInclusao] [datetime] NOT NULL,
 CONSTRAINT [PK_dbo.Papeis] PRIMARY KEY CLUSTERED 
(
    [idpapel] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

I needed this field to be created as [descrPapel] [nvarchar](200) NULL,, there is some way?

Answer 1

Using Fluent API just add the method IsOptional in the declaration of ownership.

Ex.: (in the method OnModelCreating)

modelBuilder.Entity<Papeis>()
            .Property(prop => prop.descrPapel)
            .IsOptional();

To apply as standard to strings, just do:

modelBuilder.Properties<string>().IsOptional();