EF可选一对多多重错误

Question

我有一个非常简单的模式，进一步对这个问题简化

Table: Airport 
IATA char(3) Primary Key 
Name varchar(20) 

Table: Airport_Terminal 
IATA char(3) (comp key1) 
TerminalName (comp key2) 

POCOs 
public sealed class Airport 
{ 
    [Key] 
    public string IATA { get; set; }  

    public string Name { get; set; } 

    public ICollection<AirportTerminal> Terminals { get; set; } 
} 

    public class AirportTerminal 
{ 
    [Key, Column(Order = 0)] 
    public string IATA { get; set; } 

    [Key, Column(Order = 1)] 
    public string Terminal { get; set; } 

    public Airport Airport { get; set; } 

} 

AirportTerminal配置

modelBuilder.Entity<AirportTerminal>() 
    .HasOptional<Airport>(s => s.Airport) 
    .WithMany(s => s.Terminals) 
    .HasForeignKey(s => s.IATA); 

一些机场（在我的应用程序）有多个终端和一些不要。我只是想在终端为特定机场定义时对终端属性做出反应。如果我为每个机场输入单个记录，则此配置有效。但是，当我试图查找任何一个机场，我得到：

"One or more validation errors were detected during model generation: Multiplicity conflicts with the referential constraint in Role 'AirportTerminal_Airport_Target' in relationship 'AirportTerminal_Airport'. Because all of the properties in the Dependent Role are non-nullable, multiplicity of the Principal Role must be '1'." 

研究表明，当可选部件上存在非空的属性时发生这个错误，所以它不能被设置为null。 AirportTerminal包含两个字符串，可以为空。

任何想法？

Answer 1

考虑只使用表的键。这是最好的，而不是多个关键。放置索引约束以确保属性IATA和Terminal的唯一性。

波苏斯：

public sealed class Airport 
{ 
    [Key] 
    public Guid Id { get; set; } 

    public string IATA { get; set; }  

    public string Name { get; set; } 

    public ICollection<AirportTerminal> Terminals { get; set; } 
} 

public class AirportTerminal 
{ 
    [Key] 
    public Guid Id { get; set; } 

    public string IATA { get; set; } 

    public string Terminal { get; set; } 

    public Airport Airport { get; set; } 

    public Guid? AirportId { get; set; } 
} 

配置：

modelBuilder.Entity<AirportTerminal>() 
    .HasOptional<Airport>(s => s.Airport) 
    .WithMany(s => s.Terminals) 
    .HasForeignKey(s => s.AirportId);