Question

我有以下表格：

LANDLORD = Id（主键），FirstName，Surname，EmailAddress，Title;
PROPERTY = Id（主键），类型，NumberOfBedrooms，Address1，Address2，City，County，PostCode，LandlordId（Landlord实体的外键）;

我的域类是：

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; }

}

我的Fluent NHibernate地图是：

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");
    }
}

为了测试房东被保存到数据库，我有以下代码：

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();

    }
}

当我调用SaveOrUpdate时，我收到此错误：

无法插入：[Homes4U.Service.DomainClasses.Property] [SQL：INSERT INTO PROPERTY（Type，NumberOfBedrooms，Address1，Address2，City，County，PostCode，LandlordId）VALUES（？，？，？，？，？，？，？，？）;选择SCOPE_IDENTITY（）]

现在有人为什么会这样吗？

Answer 1

在映射中，您已指定Property对象负责保存对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();

当您尝试保存对象时，Properties集合中的Property对象没有引用它所属的房东。在引擎盖下，它将尝试在LandlordId列中插入NULL。

这就是你收到错误的原因。

修改

要解决，请先保存房东，不要引用任何财产。

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);

您可能需要在保存后重新加载房东。

编辑2

在Inverse上查看此问题。

Inverse Attribute in NHibernate

流利的nhibernate hasmany关系无法插入

1 个答案: