EF Core 5.0 加入多对多使得一对多无法确定

Question

我想利用 ef core 5.0 中新的多对多功能。 https://docs.microsoft.com/en-us/ef/core/modeling/relationships?tabs=fluent-api%2Cfluent-api-simple-key%2Csimple-key

我现有的类是

public class User : IdentityUser<int>
{
}

和

public class Notification
{
    public int ID { get; set; }
    public string Title { get; set; }
    public string Message { get; set; }
    public DateTime Created { get; set; }
    public DateTime Updated { get; set; }
    public User Creator { get; set; }
    public User Updater { get; set; }
    public Notification()
    {
    }
}

我想在它们之间添加多对多关系，所以类是

public class User : IdentityUser<int>
{
    public ICollection<Notification> Notifications { get; set; }
}

和

public class Notification
{
    //[...]
    public ICollection<User> Recipients { get; set; }
}

现在 dotnet ef migrations add NotificationRecipients 结果是 Unable to determine the relationship represented by navigation 'Notification.Recipients' of type 'ICollection<User>'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

经过一些研究，我找到了 [InverseProperty()] 注释，所以我将它添加到 Notification.cs

public class Notification
{
    //[...]
    [InverseProperty("Notifications")]
    public ICollection<User> Recipients { get; set; }
}

现在似乎解决了多对多问题，但是 dotnet ef migrations add NotificationRecipients 结果是 Unable to determine the relationship represented by navigation 'Notification.Creator' of type 'User'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

是否有任何注释可以添加到 Notification.Creator 和 Notification.Updater 或任何其他方式来定义 User 和 Notification 之间的一对多关系？

我正在使用 MSSQL 作为数据库。

Answer 1

两个实体之间的多重关系通常无法自动确定，需要配置。 EF Core 中的很多东西（尤其是关系相关的）只能用 fluent API.

配置

因此，无需寻找不存在或不直观的数据注释，只需流畅地配置所需的关系（至少 - 导航属性和基数）：

modelBuilder.Entity<Notification>(builder =>
{
    builder.HasOne(e => e.Creator).WithMany();
    builder.HasOne(e => e.Updater).WithMany();
    builder.HasMany(e => e.Recipients).WithMany(e => e.Notifications);
});

EF Core 5.0 加入多对多使得一对多无法确定

EF Core 5.0 Adding many-to-many makes one-to-many unable to determine

c#

entity-framework

ef-core-5.0