Question

我有两个实体Country and Business。

public class Country
{
    public int Id { get; set; }
    public string Name { get; set; }

    public virtual ICollection<Business> Businesses { get; set; }

    public Country()
    {
        Businesses = new List<Business>();
    }
}

public class Business
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public ICollection<Country> Countries { get; set; }

        public Business()
        {
            Countries = new List<Country>();
        }
    }

国家内部可以有许多企业，许多国家都有企业。企业在国内应该是独一无二的。

如何在多对多关系中为国家/地区创造独特的业务？

Answer 1

您可以使用复合键完成此操作。

首先，您需要第三个实体来表示关联：

public class CountryBusiness {
    public int CountryId {get; set;}
    public Country Country {get; set;}

    public int BusinessId {get; set;}
    public Business Business {get; set;}
}

然后，您需要在DbContext类中为它提供一个复合键：

protected override void OnModelCreating(ModelBuilder builder)
{
    base.OnModelCreating(builder);
    builder.Entity<CountryBusiness>().HasKey(cb => new {cb.CountryId, cb.BusinessId});
}

多对多关系和独特约束。我如何在EF Core中执行此操作？

1 个答案: