如何在EF6中字符串类型的字段上创建唯一约束？

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;

public class YourEntity
{
    [Key]
    public int Id { get; set; }

    [Index(IsUnique = true)]
    [MaxLength(100)] // 设置字段的最大长度
    public string YourStringField { get; set; }
}

public class YourDbContext : DbContext
{
    public DbSet<YourEntity> YourEntities { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<YourEntity>().Property(x => x.YourStringField).HasMaxLength(100);
    }
}

using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;

public class YourEntity
{
    public int Id { get; set; }

    public string YourStringField { get; set; }
}

public class YourDbContext : DbContext
{
    public DbSet<YourEntity> YourEntities { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<YourEntity>()
            .Property(x => x.YourStringField)
            .HasMaxLength(100) // 设置字段的最大长度
            .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute { IsUnique = true }));
    }
}