NHibernate 左外连接子类

Question

我有 2 个实体产品和图像。并非所有图像都是产品图像，图像是以下文件的子类，是我的实体。我需要找到与产品无关的所有图像。我是实体检索的新手，并且尝试了多种方法。任何想法或链接将不胜感激。

public class File
    {
        #region Feilds
        public virtual int Id { get; set; }
        public virtual string Name { get; set; }
        public virtual Enumerations.File.FileType Type { get; set; }
        public virtual string Extension { get; set; }
        public virtual string Path { get; set; }
        public virtual DateTime DateCreated { get; set; }
        public virtual DateTime DateModified { get; set; }
        #endregion
    }

public class Image : File
{
    #region Fields
    public virtual string ImageName { get; set; }
    public virtual string Description { get; set; }
    public virtual bool Active { get; set; }
    public virtual DateTime DateTaken { get; set; }
    #endregion
}

public class Product
{
    #region Properties
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual string Description { get; set; }
    public virtual decimal Price { get; set; }
    public virtual decimal Weight { get; set; }
    public virtual bool IsDigital { get; set; }
    public virtual DateTime DateCreated { get; set; }
    public virtual IList<Category> ProductCategories { get; set; }
    public virtual IList<ProductAttribute> ProductAttributes { get; set; }
    public virtual IList<Image> ProductImages { get; set; }
    #endregion
}

Answer 1

您可以使用 Critiria 不存在子查询...

IList<Image> images = session.CreateCriteria<Image>("img")
        .Add(Expression.Not(Subqueries.Exists(DetachedCriteria.For<ProductImageLink>("pil")
                    .SetProjection(Projections.Constant(1))
                    .Add(Expression.EqProperty("img.image_id", "pil.image_id")))))
        .List<Image>();

其中 ProductImageLink 是关联表。

应该会产生如下查询...

select ... from image img where not exists(select 1 from productimagelink pil where img.image_id = pil.image_id);