C# 实体框架核心和多对多关系

我尝试将一个小应用程序迁移到实体框架核心，但我无法使多对多关系正常工作。 首先是我的

实体

public class Currency : Entity<int>, IMayHaveUser
{
    public string Code { get; set; }
    public string Name { get; set; }
    public string Symbol { get; set; }
    public virtual List<CountryCurrency> CountryCurrencies { get; set; }
    public bool IsUserDefined => User != null;
    [ForeignKey("UserId")]
    public virtual User User { get; set; }
    public long? UserId { get; set; }
}
public class Country : Entity<int>, IMayHaveUser 
{
    public string Iso2Code { get; set; }
    public virtual ICollection<Era> Eras { get; set; }
    public string Name { get; set; }
    public virtual List<CountryCurrency> CountryCurrencies { get; set; }
    [NotMapped]
    public bool IsUserDefined => User != null;
    [ForeignKey("UserId")]
    public virtual User User { get; set; }
    public long? UserId { get; set; }
}
public class CountryCurrency : Entity<Guid>
{
    public int CountryId { get; set; }
    public Country Country { get; set; }
    public int CurrencyId { get; set; }
    public Currency Currency { get; set; }
}

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我无法获取货币id已设置，但属性不…

您还必须包括货币实体，而不仅仅是连接实体

Country = context.Countries
    .Include(country => country.CountryCurrencies)
        .ThenInclude(e => e.Currency)
    .First();

---

您还必须包括货币实体，而不仅仅是联接实体

Country = context.Countries
    .Include(country => country.CountryCurrencies)
        .ThenInclude(e => e.Currency)
    .First();

Country = context.Countries.Include(country => country.CountryCurrencies).First();

Country = context.Countries
    .Include(country => country.CountryCurrencies)
        .ThenInclude(e => e.Currency)
    .First();