Question

我将尝试在此处仅放置模型的相关部分，因为有很多类。希望它足以解决问题：

public class Solve
{
    public int SolveID { get; set; }

    public int LocationID { get; set; }
    public virtual Location Location { get; set; }

    public int ProfileID { get; set; }
    public virtual Profile Profile { get; set; }

    public int BillID { get; set; }
    public virtual Bill Bill { get; set; }

    public int? PanelID { get; set; }
    public virtual Panel Panel { get; set; }
}

public class Location
{
    public int LocationID { get; set; }

    [Index]
    [StringLength(48)]
    public string Name  { get; set; }

    [Index]
    public State State { get; set; }

    public double Latitude  { get; set; }
    public double Longitude { get; set; }

    public virtual List<Profile> Profiles { get; set; }
}

public class Profile
{
    public int ProfileID { get; set; }

    public int LocationID { get; set; }
    public virtual Location Location { get; set; }

    public double Capacity { get; set; }

    public virtual List<ProfileSample> ProfileSamples { get; set; }
}

public class ProfileSample
{
    [Key, ForeignKey("Profile")]
    [Column(Order = 1)]
    public int ProfileID { get; set; }
    public virtual Profile Profile { get; set; }

    [Key]
    [Column(Order = 2)]
    [DataType(DataType.Date)]
    public DateTime Date { get; set; }

    [Key]
    [Column(Order = 3)]
    public TimeSpan TimeOfDay { get; set; }

    public double SampleValue { get; set; }
}

所以在我引入Solve类之前一切正常，此时它开始抱怨“多个级联路径”。我在上下文中添加了以下内容，从那时起它似乎没问题了：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Solve>()
        .HasRequired(s => s.Location)
        .WithRequiredDependent()
        .WillCascadeOnDelete(false);
}

除非表现不正常：

using (Model.BlueData bd = new Model.BlueData())
{
    Random rng = new Random();

    s = new Model.Solve()
    {
        Location = bd.Locations.Find(rng.Next(0, bd.Locations.Count())),
        Bill     = bd.Bills.Find(rng.Next(0, bd.Bills.Count())),
        Profile  = bd.Profiles.Find(rng.Next(0, bd.Profiles.Count()))
    };

    bd.Solves.Add(s);
    bd.SaveChanges();

    s = bd.Solves
        .Where(u => u.SolveID == s.SolveID)
        .Include(u => u.Location)
        .Include(u => u.Profile)
        .Include(u => u.Profile.ProfileSamples)
        .Include(u => u.Bill)
        .FirstOrDefault();
}

因此，上面的代码只生成一个随机Solve对象，将其添加到数据上下文中，然后再次检索它以及所有相关数据。肯定有一种更优雅的方式，但现在这只是测试代码，以确保我的应用程序的其他部分正常工作。

正如预期的那样，当我创建Solve s对象时，s.Location是一个特定的位置，带有ID，例如1609，当然还有s.LocationID和{{ 1}}都等于s.SolveID。

将数据添加到数据上下文并保存更改后，0等于该位置的ID（在此示例中为s.SolveID）。这很奇怪。我尝试在1609类中向[Key]和SolveID添加[ForeignKey("Location")]属性，但没有区别。

我尝试了从LocationID删除Solve或从位置删除Profile等各种内容。我现在还不记得了，但是有些事情确实可以纠正Solve设置到该位置的ID行为。

但是这些属性都是有原因的，如果可能的话，我宁愿不必删除它们只是为了让它工作。我不明白为什么会这样，或者如何正确地纠正它。我感谢任何协助。

Answer 1

首先在Location对象中引用Solve，所以位置是主体，求解是依赖的，我认为在这种情况下这种映射是错误的 -

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Solve>()
        .HasRequired(s => s.Location)
        .WithRequiredDependent()
        .WillCascadeOnDelete(false);
}

应该是 -

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Solve>()
        .HasRequired(s => s.Location)
        .WillCascadeOnDelete(false);
}

其次，由于Solve引用外键，定义应该是 -

public class Solve
{
    public int SolveID { get; set; }

    [ForeignKey("Location")]
    public int LocationID { get; set; }
    public virtual Location Location { get; set; }

    [ForeignKey("Profile")]
    public int ProfileID { get; set; }
    public virtual Profile Profile { get; set; }

    [ForeignKey("Bill")]
    public int BillID { get; set; }
    public virtual Bill Bill { get; set; }

    [ForeignKey("Panel")]
    public int? PanelID { get; set; }
    public virtual Panel Panel { get; set; }
}

第三，保存对象时，必须首先保存1）主要对象，否则EF将尝试创建新条目或2）您必须手动附加它们。其中最容易发现的是（1），保存主要结束后，我只分配外键，EF按预期工作。

using (Model.BlueData bd = new Model.BlueData())
{
    Random rng = new Random();

    s = new Model.Solve()
    {
        LocationID = bd.Locations.Find(rng.Next(0, bd.Locations.Count())).LocationID,
        BillID     = bd.Bills.Find(rng.Next(0, bd.Bills.Count())).BillID,
        ProfileID  = bd.Profiles.Find(rng.Next(0, bd.Profiles.Count())).ProfileID
    };
    s.Bill = s.Location = s.Profile = null; //otherwise EF tries to create them
    bd.Solves.Add(s);
    bd.SaveChanges();

    s = bd.Solves
        .Where(u => u.SolveID == s.SolveID)
        .Include(u => u.Location)
        .Include(u => u.Profile)
        .Include(u => u.Profile.ProfileSamples)
        .Include(u => u.Bill)
        .FirstOrDefault();
}

编辑1：位置类 -

public class Location
{
    [Key]  //mark location ID as primary key
    public int LocationID { get; set; }

    [Index]
    [StringLength(48)]
    public string Name  { get; set; }

    [Index]
    public State State { get; set; }

    public double Latitude  { get; set; }
    public double Longitude { get; set; }

    public virtual List<Profile> Profiles { get; set; }
}

EF6 Code First，多个级联路径和奇怪的FK行为

1 个答案: