訪問父實體從孩子實體框架

Question

我有一個包含像這樣

public class Device 
{ 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.None)] 
    public long DeviceSerial { get; set; } 

    public virtual ICollection<DeviceLogEntry> Errors { get; set; } 
} 

這工作得很好DeviceErrorLog設置列表的父實體Device，但我希望能夠給內DeviceLogEntry從訪問Device所以我增加了以下內容：

public class DeviceLogEntry 
{   
    [Key] 
    public int Id { get; set; } 

    public virtual Device Device { get; set; } 
} 

現在的DeviceLogEntry表我的數據庫結構與Device相關的3列：[Device_DeviceSerial],[Device_DeviceSerial1],[Device_DeviceSerial2]

我錯過了防​​止這種情況的鏈接或一段代碼嗎？

更新

我已經更新了代碼，包括設備作爲已經刪除了一個額外的列，但我仍然似乎有一個太多[Device_DeviceSerial],[Device_DeviceSerial1]

public class DeviceLogEntry 
{   
    [Key, Column(Order = 0)] 
    public int Id { get; set; } 

    [Key, Column(Order = 1)] 
    [ForeignKey("Device")] 
    public long DeviceSerial { get; set; } 
} 

Answer 1

您重新嘗試的外鍵來模擬一對多的關係。子實體在數據庫中需要一個外鍵給父母的ID，但是你沒有遵循命名約定，所以EF不知道他們正在建模相同的關係，併爲'DeviceSerial'屬性添加了獨立的列，'Errors'屬性和'設備'屬性。試試這個：

public class Device 
{ 
    //You need the Key annotation because the name does not follow the 
    //convention for a Key 
    //if you'd called it "DeviceID" or "ID" then you wouldn't need it 
    [Key] 
    //EF defaults int keys to Identity 
    //assuming longs are the same you need this annotation to stop that 
    [DatabaseGenerated(DatabaseGeneratedOption.None)] 
    public long DeviceSerial { get; set; } 

    //This is a navigation property. 
    //The virtual keyword lets EF override the method in a proxy class 
    //so that it can support lazy loading. 
    //Convention would name it "DeviceLogEntries" 
    public virtual ICollection<DeviceLogEntry> Errors { get; set; } 
} 

public class DeviceLogEntry 
{   
    //You don't need the Key annotation 
    public int Id { get; set; }   

    //You don't have to include the foreign key AND the navigation property 
    //in the entity but life is probably easier if you do... 
    public long DeviceSerial { get; set; } 

    //...so I would add the navigation property to your entity 
    //Foreign key doesn't follow convention (it's not "DeviceID") 
    //so you need to tell it what it is 
    [ForeignKey("DeviceSerial")] 
    //And again if the navigation property in the parent had been named 
    //"DeviceLogEntries" then you wouldn't need to tell EF that the 
    //inverse navigation property is actually called "Errors" 
    [InverseProperty("Errors")] 
    public virtual Device Device {get;set;) 
} 

參考文獻：

Code First Data Annotations

Making Do with Absent Foreign Keys