NHibernate代码映射包连接两个表

Question

I have the following definition for a Transaction (as in purchase details) object :

public class Transaction : MappingObject
{
    public virtual int Id { get; set; }
    public virtual IList<TransactionProduct> Products { get; set; }
}

public class TransactionMap : ClassMapping<Transaction>
{
    public TransactionMap()
    {
        Table("TRANSACTIONS_TBL");
        Id(x => x.Id, m =>
        {
            m.Column("ID");
            m.Generator(Generators.Identity);
        });
        Bag(x => x.Products, m =>
        {
            m.Inverse(true);
            m.Table("TRANSACTION_PRODUCTS_TBL");
            m.Key(k => k.Column("TRANSACTION_ID"));
            m.Lazy(CollectionLazy.NoLazy);
        }, 
        relation => relation.OneToMany(mapper => mapper.Class(typeof(TransactionProduct))));
    }
}

And TransactionProduct is defined like this :

public class TransactionProduct : MappingObject
{
    public virtual int TransactionId { get; set; }
    public virtual int ProductId { get; set; }
    public virtual int Quantity { get; set; }

    public override bool Equals(object obj)
    {
        var t = obj as TransactionProduct;
        if (t == null)
            return false;
        if (TransactionId == t.TransactionId && ProductId == t.ProductId)
            return true;
        return false;
    }
    public override int GetHashCode()
    {
        return (TransactionId + "|" + ProductId).GetHashCode();
    }
}

public class TransactionProductMap : ClassMapping<TransactionProduct>
{
    public TransactionProductMap()
    {
        Table("TRANSACTION_PRODUCTS_TBL");
        ComposedId(map =>
        {
            map.Property(x => x.TransactionId, m => m.Column("TRANSACTION_ID"));
            map.Property(x => x.ProductId, m => m.Column("PRODUCT_ID"));
        });
        Property(x => x.Quantity, m => m.Column("QUANTITY"));
    }
}

Now, I want to select a transaction and populate the Products array in a single select (I know I can select the transaction then the products but It's bad practice)

So I'm using this :

        using (var session = CommonDAL.GetSession())
        {
            Transaction transactionAlias = null;
            TransactionProduct transactionProductAlias = null;

            return session.QueryOver(() => transactionAlias).
                JoinAlias(() => transactionAlias.Products, () => transactionProductAlias).
                Where(() => transactionAlias.Id == transactionProductAlias.TransactionId).List().ToList();
        }

This work's quite well but the problem is that if I have a transaction with 2 products, I get 2 transaction objects with 2 products inside them, same goes for if I have a transaction with 4 products, I get 4 transaction objects with 4 products. The transaction objects are good, but the problem is the duplicates.

I can probably solve it with Distinct() but again, I want best practice

Answer 1

我在Where(...)之后使用.TransformUsing(Transformers.DistinctRootEntity)解决了它