功能NHibernate的hasMany關係無法插入

Question

我有以下表格：

• 業主= ID（主鍵），名字，姓氏，EmailAddress的，題目;
• PROPERTY = Id（主鍵），Type，NumberOfBrooms，Address1，Address2，City，County，PostCode，LandlordId（業主實體的外鍵）;

我的域類：

public class Landlord:BaseEntity 
{ 
    public virtual string Title { get; set; } 
    public virtual string Surname { get; set; } 
    public virtual string FirstName { get; set; } 
    public virtual string EmailAddress { get; set; } 
    public virtual IList<Property> Properties { get; set; } 

    public Landlord() 
    { 
     Properties = new List<Property>(); 
    } 
} 

public class Property:BaseEntity 
{ 
    public virtual string Type { get; set; } 
    public virtual int NumberOfBedrooms { get; set;} 
    public virtual string Address1 { get; set; } 
    public virtual string Address2 { get; set; } 
    public virtual string City { get; set; } 
    public virtual string County { get; set; } 
    public virtual string PostCode { get; set; } 
    public virtual Landlord Landlord { get; set; } 

} 

我流利的NHibernate的地圖是：

public sealed class LandlordMap:ClassMap<Landlord> 
{ 
    public LandlordMap() 
    { 
     Id(x => x.Id).GeneratedBy.Identity(); 
     Map(x => x.Title); 
     Map(x => x.Surname); 
     Map(x => x.FirstName); 
     Map(x => x.EmailAddress); 
     HasMany(x => x.Properties) 
      .KeyColumns.Add("LandlordId") 
      .Inverse() 
      .Cascade.All(); 
     Table("LANDLORD"); 
    } 
} 

public sealed class PropertyMap:ClassMap<Property> 
{ 
    public PropertyMap() 
    { 
     Id(x => x.Id).GeneratedBy.Identity(); 
     Map(x => x.Type); 
     Map(x => x.NumberOfBedrooms); 
     Map(x => x.Address1); 
     Map(x => x.Address2); 
     Map(x => x.City); 
     Map(x => x.County); 
     Map(x => x.PostCode); 
     References(x => x.Landlord, "LandlordId"); 
     Table("PROPERTY"); 
    } 
} 

要測試房東被保存到數據庫中，我有以下代碼：

public class Program 
{ 
    static void Main(string[] args) 
    { 
     ILandlordRepository rep = new LandlordRepository(); 

     //Create property object 
     Property p1 = new Property 
     { 
      Address1 = "123 LA Road", 
      Address2 = "Bilston", 
      City = "Harlem", 
      County = "West Mids", 
      NumberOfBedrooms = 2, 
      PostCode = "wv134wd", 
      Type = "Bungalow" 
     }; 

     //Create landlord and assign property 
     var landlord = new Landlord(); 
     landlord.Title = "Dr"; 
     landlord.FirstName = "Rohit"; 
     landlord.Surname = "Kumar"; 
     landlord.EmailAddress = "rkhkp@p.com"; 
     landlord.Properties.Add(p1); 

     //Add to the database 
     rep.SaveOrUpdate(landlord); 


     Console.ReadKey(); 

    } 
} 

當我打電話SaveOrUpdate我得到這個錯誤：

could not insert: [Homes4U.Service.DomainClasses.Property][SQL: INSERT INTO PROPERTY (Type, NumberOfBedrooms, Address1, Address2, City, County, PostCode, LandlordId) VALUES (?, ?, ?, ?, ?, ?, ?, ?); select SCOPE_IDENTITY()]

現在有人爲什麼會發生這種情況嗎？

Answer 1

在您的映射中，您已指定Property對象負責保存對Landlord的引用。

HasMany(x => x.Properties) 
      .KeyColumns.Add("LandlordId") 
      // Inverse means that the other side of the 
      // relationship is responsible for creating the reference 
      .Inverse() 
      .Cascade.All(); 

當您嘗試保存該對象時，屬性集合中的Property對象沒有對它所屬的房東的引用。在引擎蓋下，它會嘗試將NULL插入到LandlordId列中。

這就是爲什麼你會得到你的錯誤。

編輯

要解決問題，首先保存房東，沒有任何屬性的引用。

ILandlordRepository rep = new LandlordRepository(); 
    IPropertyRepository pro = new PropertyRepository(); 

    //Create landlord 
    var landlord = new Landlord(); 
    landlord.Title = "Dr"; 
    landlord.FirstName = "Rohit"; 
    landlord.Surname = "Kumar"; 
    landlord.EmailAddress = "rkhkp@p.com"; 

    rep.SaveOrUpdate(landlord); 

    // Now add the landlord reference to the property and 
    // save 
    /Create property object 
    Property p1 = new Property 
    { 
     Address1 = "123 LA Road", 
     Address2 = "Bilston", 
     City = "Harlem", 
     County = "West Mids", 
     NumberOfBedrooms = 2, 
     PostCode = "wv134wd", 
     Type = "Bungalow", 
     Landlord = landlord 
    }; 

    pro.SaveOrUpdate(p1); 

您可能需要重新加載樓主後保存它。

EDIT 2

見逆這個問題。

Inverse Attribute in NHibernate