实体框架自动外键填充

是否有任何方法可以强制实体框架在将实体添加到上下文时立即填充外键，而不是将其延迟到上下文发生其他事情？当使用数据绑定来显示引用的实体时，这种默认行为没有太大帮助。

仅从上下文引用任何DbSet就足以迫使EF填充所添加的Children的Parent和Parent_Name。但CCD_ 5似乎迫使EF填充CCD_ 6或CCD_ 7。

我真的很想用[Required]属性标记Reference_Name，这样它在数据库中就会是Not Null，但如果我这样做，我在尝试调用SaveChanges时会收到验证错误，除非我明确设置了Reference_Name，即使如果设置了Reference，SaveChanges本身也会正确填充Reference_Name。

我真的希望能够设置Reference或Reference_Name中的任何一个，并能够立即使用另一个。同样，我希望在添加Child对象后能够立即使用Parent或Parent_Name，而不必使用先从上下文访问其他元素的杂烩。

有人能帮助我理解EF延迟这些事情的原因吗？以及我如何强制它填充外键属性或外键列，最好是立即填充，但至少不必调用SaveChanges？当EF无论如何都要正确填充所有属性时，我真的不想显式地完全填充它们。

public class OracleContext : DbContext
{
    public virtual DbSet<Parent> Parents { get; set; }
    public virtual DbSet<Child> Children { get; set; }
    public virtual DbSet<Reference> References { get; set; }
    public virtual DbSet<SomethingElse> SomethingElses { get; set; }
}
public class Parent
{
    [Key, MaxLength(30)]
    public string Name { get; set; }
    [InverseProperty("Parent")]
    public virtual List<Child> Children { get; set; } = new List<Child>();
}
public class Child
{
    [Key, Column(Order = 1), MaxLength(30)]
    public string Parent_Name { get; set; }
    [Key, Column(Order = 2), MaxLength(30)]
    public string Name { get; set; }
    public string Reference_Name { get; set; }
    [ForeignKey("Parent_Name")]
    public virtual Parent Parent { get; set; }
    [ForeignKey("Reference_Name")]
    public virtual Reference Reference { get; set; }
    public Child Clone()
    {
        return new Child
        {
            Parent_Name = this.Parent_Name,
            Name = this.Name,
            Reference_Name = this.Reference_Name,
            Parent = this.Parent,
            Reference = this.Reference
        };
    }
}
public class Reference
{
    [Key, MaxLength(30)]
    public string Name { get; set; }
}
public class SomethingElse
{
    [Key, MaxLength(30)]
    public string Name { get; set; }
}
private void button1_Click(object sender, EventArgs e)
{
    OracleContext context = new OracleContext();
    Reference reference = context.References.Add(new Reference { Name = "Reference" });
    Parent alpha = context.Parents.Add(new Parent { Name = "Alpha" });
    Child alphaOne = new Child { Name = "AlphaOne" };
    Child alphatwo = new Child { Name = "AlphaTwo", Reference_Name = "Reference" };
    alpha.Children.AddRange(new List<Child> { alphaOne, alphatwo });
    alphaOne.Reference = reference;
    var list = (
            from child in alpha.Children
            select new
            {
                Time = "Before referencing SomethingElses.Local",
                Child = child.Clone()
            }
        ).ToList();
    var x = context.SomethingElses.Local;
    list.AddRange(
            from child in alpha.Children
            select new
            {
                Time = "After referencing SomethingElses.Local",
                Child = child.Clone()
            }
        );
    list.AddRange(
            from parent in context.Parents.Local
            from child in parent.Children
            select new
            {
                Time = "Before SaveChanges",
                Child = child.Clone()
            }
        );
    context.SaveChanges();
    list.AddRange(
            from parent in context.Parents.Local
            from child in parent.Children
            select new
            {
                Time = "After SaveChanges",
                Child = child.Clone()
            }
        );
    foreach (var item in list)
    {
        Console.WriteLine("{0}:'r'n'tName = '{1}''r'n'tParent = '{2}' ({3})'r'n'tReference = '{4}' ({5})",
            item.Time, item.Child.Name, item.Child.Parent_Name, item.Child.Parent, item.Child.Reference_Name, item.Child.Reference);
    }
}
Before referencing SomethingElses.Local:
    Name = 'AlphaOne'
    Parent = '' ()
    Reference = '' (WindowsFormsApplication2.Reference)
Before referencing SomethingElses.Local:
    Name = 'AlphaTwo'
    Parent = '' ()
    Reference = 'Reference' ()
After referencing SomethingElses.Local:
    Name = 'AlphaOne'
    Parent = 'Alpha' (WindowsFormsApplication2.Parent)
    Reference = '' (WindowsFormsApplication2.Reference)
After referencing SomethingElses.Local:
    Name = 'AlphaTwo'
    Parent = 'Alpha' (WindowsFormsApplication2.Parent)
    Reference = 'Reference' ()
Before SaveChanges:
    Name = 'AlphaOne'
    Parent = 'Alpha' (WindowsFormsApplication2.Parent)
    Reference = '' (WindowsFormsApplication2.Reference)
Before SaveChanges:
    Name = 'AlphaTwo'
    Parent = 'Alpha' (WindowsFormsApplication2.Parent)
    Reference = 'Reference' ()
After SaveChanges:
    Name = 'AlphaOne'
    Parent = 'Alpha' (WindowsFormsApplication2.Parent)
    Reference = 'Reference' (WindowsFormsApplication2.Reference)
After SaveChanges:
    Name = 'AlphaTwo'
    Parent = 'Alpha' (WindowsFormsApplication2.Parent)
    Reference = 'Reference' (WindowsFormsApplication2.Reference)