Question

public class Product : EntityBase<Product, int>, IAggregateRoot
{
    public virtual string ProductName { get; set; }
    public virtual List<ProductDetail> Description { get; set; }
}

public class ProductDetail : EntityBase<ProductDetail, int>, IAggregateRoot
{
    public virtual string Description { get; set; }
    public virtual Product Product { get; set; }
}

上述产品实体有多个ProductDetails。我的映射如下：

public class ProductMap : ClassMapping<Product>
{
    public ProductMap()
    {
        Lazy(false);
        Table("Product");

        Id(x => x.ID, map => { map.Column("ID"); map.Generator(Generators.Native); });
        Property(x => x.ProductName, map => map.NotNullable(true));

        Bag(x => x.Description, m => {
            m.Inverse(true); // Is collection inverse?
            m.Cascade(Cascade.All); //set cascade strategy
            m.Key(k => k.Column(col => col.Name("ProductID"))); //foreign key in Detail table
        }, a => a.OneToMany());
    }
}

public class ProductDetailMap : ClassMapping<ProductDetail>
{
    public ProductDetailMap()
    {
        Lazy(false);
        Table("ProductDetail");

        Id(x => x.ID, map => { map.Column("ID"); map.Generator(Generators.Native); });
        Property(x => x.Description, map => map.NotNullable(false));

        ManyToOne(x => x.Product, x =>
        {
            x.Column("ProductID");
        });
    }
}

当我保存这个;我得到了错误。

NHibernate.dll中发生了'NHibernate.PropertyAccessException'类型的异常，但未在用户代码中处理附加信息：无效的转换（检查您的映射是否存在属性类型不匹配）;

Answer 1

对于地图集合，我们必须使用接口（ IList<> ）

public class Product : EntityBase<Product, int>, IAggregateRoot
{
    public virtual string ProductName { get; set; }
  //public virtual List<ProductDetail>  Description { get; set; }
    public virtual IList<ProductDetail> Description { get; set; }
}

NHibernate会注入自己的IList<>实现 - 这不是List的孩子......这是代理所需要的。 ..懒加载

NHibernate一对多映射和保存

1 个答案: