我有一个 Ticket
实体:
public class Ticket
{
public int Id { get; set; }
public string Title { get; set; }
public virtual ICollection<Relation> RelatedTickets { get; set; }
}
我想在 Entity Framework Core 中设置多对多的自关系,所以我做了两个一对多的关系:
public class Relation
{
[Required, ForeignKey("TicketFrom")]
public int FromId { get; set; }
[Required, ForeignKey("TicketTo")]
public int ToId { get; set; }
public virtual Ticket TicketFrom { get; set; }
public virtual Ticket TicketTo { get; set; }
}
我尝试使用 fluent API 创建关系:
builder.Entity<Relation>()
.HasKey(uc => new { uc.FromId, uc.ToId });
builder.Entity<Relation>()
.HasOne(c => c.TicketFrom)
.WithMany(p => p.RelatedTickets)
.HasForeignKey(pc => pc.FromId);
builder.Entity<Relation>()
.HasOne(c => c.TicketTo)
.WithMany(p => p.RelatedTickets)
.HasForeignKey(pc => pc.ToId);
但结果我有一个错误:
Cannot create a relationship between 'Ticket.RelatedTickets' and 'Relation.TicketTo', because there already is a relationship between 'Ticket.RelatedTickets' and 'Relation.TicketForm'. Navigation properties can only participate in a single relationship.
可能的解决方案是将 Parent 关系直接添加到
TicketEntity
:public class Ticket
{
public int Id { get; set; }
[Required, ForeignKey("ParentRelation")]
public Nullable<int> ParentRelationId { get; set; }
public virtual Ticket ParentRelation {get;set;}
public virtual ICollection<Ticket> RelatedTickets { get; set; }
...
}
像这样流畅的api:
modelBuilder.Entity<Ticket> =>
{
entity
.HasMany(e => e.RelatedTickets)
.WithOne(e => e.ParentRelation)
.HasForeignKey(e => e.ParentRelationId );
});
但是像这样存储父关系看起来很“脏”。
什么是正确的方法?
最佳答案
不可能只有一个带有关系的集合。你需要两个 - 一个有关系的票等于 TicketFrom
第二个关系票等于TicketTo
.
像这样的东西:
模型:
public class Ticket
{
public int Id { get; set; }
public string Title { get; set; }
public virtual ICollection<Relation> RelatedTo { get; set; }
public virtual ICollection<Relation> RelatedFrom { get; set; }
}
public class Relation
{
public int FromId { get; set; }
public int ToId { get; set; }
public virtual Ticket TicketFrom { get; set; }
public virtual Ticket TicketTo { get; set; }
}
配置:
modelBuilder.Entity<Relation>()
.HasKey(e => new { e.FromId, e.ToId });
modelBuilder.Entity<Relation>()
.HasOne(e => e.TicketFrom)
.WithMany(e => e.RelatedTo)
.HasForeignKey(e => e.FromId);
modelBuilder.Entity<Relation>()
.HasOne(e => e.TicketTo)
.WithMany(e => e.RelatedFrom)
.HasForeignKey(e => e.ToId);
请注意,使用 Parent 的解决方案并不等效,因为它会创建
one-to-many
协会,而如果我理解正确,您正在寻找 many-to-many
.
关于asp.net-core - 自引用多对多关系,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39728016/