無法在VB.NET中使用Fluent API定義複合PK

Question

我想爲一個類定義一個組合PK，其中一列是FK到另一個表。代碼編譯沒有任何錯誤，但是當我嘗試遷移改變我碰到下面的錯誤

PM> Update-Database -Force -TargetMigration:0 
Specify the '-Verbose' flag to view the SQL statements being applied to the target database. 
System.InvalidOperationException: The properties expression 'x => new VB$AnonymousType_0`2(RtepNumber = x.RtepNumber, ContractId = x.Contract.ContractId)' is not valid. The expression should represent a property: C#: 't => t.MyProperty' VB.Net: 'Function(t) t.MyProperty'. When specifying multiple properties use an anonymous type: C#: 't => new { t.MyProperty1, t.MyProperty2 }' VB.Net: 'Function(t) New With { t.MyProperty1, t.MyProperty2 }'. 

The properties expression 'x => new VB$AnonymousType_0`2(RtepNumber = x.RtepNumber, ContractId = x.Contract.ContractId)' is not valid. The expression should represent a property: C#: 't => t.MyProperty' VB.Net: 'Function(t) t.MyProperty'. When specifying multiple properties use an anonymous type: C#: 't => new { t.MyProperty1, t.MyProperty2 }' VB.Net: 'Function(t) New With { t.MyProperty1, t.MyProperty2 }'. 

然而，這是理應引起例外似乎是在被請求的語法。

考慮以下類

Public Class ParentClass 
    Public Property ParentClassId as String 

    Public Property Title As String 

    Public Property ChildClasses As ICollection(Of ChildClass) 
End Class 

Public Class ChildClass  
    Public Property ParentClass As ParentClass 

    Public Property ChildClassId As String 

    Public Property Title As String 
End Class 

而下面流利的API代碼

Protected Overrides Sub OnModelCreating(ByVal modelBuilder As System.Data.Entity.DbModelBuilder) 
    MyBase.OnModelCreating(modelBuilder) 

    modelBuilder.Entity(Of Models.ChildClass).HasRequired(Function(x) x.ParentClass).WithMany(Function(x) x.ChildClasses).Map(Function(x) x.MapKey("ContractId")) 

    modelBuilder.Entity(Of Models.ChildClass).HasKey(Function(x) New With {x.ParentClass.ParentClassId, x.ChildClassId}) 
End Sub 

相應的SQL代碼將

CREATE TABLE [dbo].[ParentClass](
    [ParentClassId] [nvarchar](10) NOT NULL, 
    [Title] [nvarchar](25) NOT NULL, 
CONSTRAINT [PK_ParentClass] PRIMARY KEY CLUSTERED 
(
    [ParentClassId] ASC 
) 
) 
GO 

CREATE TABLE [dbo].[ChildClass](
    [ParentClassId] [nvarchar](10) NOT NULL, 
    [ChildClassId] [nvarchar](10) NOT NULL, 
    [Title] [nvarchar](25) NOT NULL, 
CONSTRAINT [PK_ChildClass] PRIMARY KEY CLUSTERED 
(
    [ParentClassId] ASC, 
    [ChildClassId] ASC 
) 
) 
GO 

ALTER TABLE [dbo].[ChildClass] WITH CHECK ADD CONSTRAINT [FK_ChildClass_ParentClass] FOREIGN  KEY([ParentClassId]) 
REFERENCES [dbo].[ParentClass] ([ParentClassId]) 
GO 

ALTER TABLE [dbo].[ChildClass] CHECK CONSTRAINT [FK_ChildClass_ParentClass] 
GO 

感謝您的幫助，您可以提供。

編輯：

更多的研究（即試驗）後，問題似乎從PK定義使用的導航屬性的遏制。所以改變代碼看起來像

Public Class ChildClass  
    Public Property ParentClassId As String 

    Public Property ChildClassId As String 

    Public Property Title As String 
End Class 

Protected Overrides Sub OnModelCreating(ByVal modelBuilder As System.Data.Entity.DbModelBuilder) 
    MyBase.OnModelCreating(modelBuilder) 

    modelBuilder.Entity(Of Models.ChildClass).HasKey(Function(x) New With {x.ParentClassId, x.ChildClassId}) 
End Sub 

清除異常但當然，我現在在ChildClass中失去了我的ParentClass導航屬性。

仍然困惑。

Answer 1

看起來你有在子類中具有標量屬性。鍵只能使用顯式標量屬性來定義。

Answer 2

你可以保持導航屬性在您的類...

Public Class ChildClass  
    Public Property ParentClassId As String 

    Public Property ChildClassId As String 

    Public Property Title As String 

    Public Property ParentClass As ParentClass 
End Class 

...然後使用HasForeignKey而不是MapKey在映射：

modelBuilder.Entity(Of Models.ChildClass). _ 
    HasKey(Function(x) New With {x.ParentClassId, x.ChildClassId}) 

modelBuilder.Entity(Of Models.ChildClass). _ 
    HasRequired(Function(x) x.ParentClass). _ 
    WithMany(Function(x) x.ChildClasses). _ 
    HasForeignKey(Function(x) x.ParentClassId) 

如果外鍵的另一在數據庫表中添加名稱映射：

modelBuilder.Entity(Of Models.ChildClass). _ 
    Property(Function(x) x.ParentClassId). _ 
    HasColumnName("ContractId")