Question

使用Entity Framework 7，我有以下实体：

public class Country {
  public String Code { get; set; }
  public String Name { get; set; }
  public virtual ICollection<User> Users { get; set; }    
}

public class User : IdentityUser<Int32> {   
  public String CountryCode { get; set; }
  public virtual Country Country { get; set; }
}

Country和User配置为：

protected override void OnModelCreating(ModelBuilder builder) {

  base.OnModelCreating(builder);

  builder.Entity<Country>().ToTable("Countries");
  builder.Entity<Country>().HasKey(x => x.Code);
  builder.Entity<Country>().Property(x => x.Code).IsRequired().HasMaximumLength(2).ValueGeneratedNever();
  builder.Entity<Country>().Property(x => x.Name).IsRequired().HasMaxLength(80);        

  builder.Entity<Country>().ToTable("Users");

  builder.Entity<Country>()
    .HasOne(x => x.Country)
    .WithMany(x => x.Users)
    .HasForeignKey(x => x.CountryCode);
}

我能够创建迁移但是当我更新数据库时，我收到以下错误：

列“Countries.Code”与引用列“Users.CountryCode”是foreighn键“FK_User_Country_CountryCode”的长度或比例不同。参与外键关系的列必须以相同的长度和比例定义。无法创建约束或索引。

我能够解决错误，但只能删除.HasMaximumLength(2)的{{1}}属性配置中的Country，所以我最终得到了：

Code

如何使其工作但保持builder.Entity<Country>().Property(x => x.Code).IsRequired().ValueGeneratedNever();列长度等于2？

Answer 1

您必须从User实体配置CountryCode属性，如：

protected override void OnModelCreating(ModelBuilder builder) 
{
    base.OnModelCreating(builder);

    builder.Entity<Country>().ToTable("Countries");
    builder.Entity<Country>().HasKey(x => x.Code);
    builder.Entity<Country>().Property(x => x.Code).IsRequired().HasMaximumLength(2).ValueGeneratedNever();
    builder.Entity<Country>().Property(x => x.Name).IsRequired().HasMaxLength(80);        

    builder.Entity<User>().ToTable("User");
    builder.Entity<User>().HasKey(x => x.CountryCode);
    builder.Entity<User>().Property(x => x.CountryCode).IsRequired().HasMaximumLength(2).ValueGeneratedNever();
    builder.Entity<User>()
        .HasOne(x => x.Country)
        .WithMany(x => x.Users)
        .HasForeignKey(x => x.CountryCode);

}

列...与引用列的长度或比例不同

1 个答案: