Persisting with Order-By

BaggaDonuts · **Joined:** Wed Jul 25, 2007 2:16 pm **Posts:** 8

I have a class that contains a set of ordered products. The set is ordered by a column 'Order' in my table and the order column does not allow nulls. When I persist this class, I get an error: cannot insert NULL into column 'Order.'

So the problem is that the Order column is not mapping when i persist but the set of products is being ordered correctly. what is the proper way of doing this?

Code:

<?xml version="1.0" encoding="utf-8" ?>

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0"
                   namespace="Com.WildTangent.ProductCatalog.Data"
                   assembly="ProductCatalog">
    <class name="RuleGroupSlot" table="t_RuleGroupSlot">
        <cache usage="read-write" />

        <id name="Id" column="RuleGroupSlotId" type="int">
            <generator class="native" />
        </id>

        <set name="OrderedProducts" table="t_ProductSlotOrder" order-by="[Order]"> 
            <key column="RuleGroupSlotId" />
            <many-to-many column="ProductId" class="Product" />
        </set>

    </class>
</hibernate-mapping>

Code:

public class RuleGroupSlot
    {
        public virtual int Id
        {
            get { return _id; }
            set { _id = value; }
        }

        // We don't have backward references to RuleGroup and Slot here for efficiency reasons

        public IProductList GetOrderedProducts()
        {
            ProductList productList = new ProductList();
            productList.Products = CollectionsUtil.ToGenericList<Product>(OrderedProducts);
            return productList;
        }

        public virtual ISet OrderedProducts
        {
            get { return _orderedProducts; }
            set { _orderedProducts = value; }
        }

        private int _id;
        private ISet _orderedProducts;
    }

[/code]

karlchu · **Posted:** Wed Jul 25, 2007 2:48 pm

Instead of using a <set>, you may use a <list> instead:

Code:

        ...
        <list name="OrderedProducts" table="t_ProductSlotOrder">
            <key column="RuleGroupSlotId" />
            <index column="`Order`"/>
            <many-to-many column="ProductId" class="Product" />
        </list>
        ...

That way, you don't need to manage the Order column at all.

BaggaDonuts · **Joined:** Wed Jul 25, 2007 2:16 pm **Posts:** 8

i get an exception when doing this. i changed to a list..
[NHibernate.LazyInitializationException] = {"Failed to lazily initialize a collection"}

here's my code:

Code:

<?xml version="1.0" encoding="utf-8" ?>

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0"
                   namespace="Com.WildTangent.ProductCatalog.Data"
                   assembly="ProductCatalog">
    <class name="RuleGroupSlot" table="t_RuleGroupSlot">
        <cache usage="read-write" />

        <id name="Id" column="RuleGroupSlotId" type="int">
            <generator class="native" />
        </id>

        <list name="OrderedProducts" table="t_ProductSlotOrder"> 
            <key column="RuleGroupSlotId" />
         <index column="[Order]" />
            <many-to-many column="ProductId" class="Product" />
        </list>

    </class>
</hibernate-mapping>

Code:

 public class RuleGroupSlot
    {
        public virtual int Id
        {
            get { return _id; }
            set { _id = value; }
        }

        // We don't have backward references to RuleGroup and Slot here for efficiency reasons

        public IProductList GetOrderedProducts()
        {
            ProductList productList = new ProductList();
            productList.Products = CollectionsUtil.ToGenericList<Product>(OrderedProducts);
            return productList;
        }

        public virtual IList OrderedProducts
        {
            get { return _orderedProducts; }
            set { _orderedProducts = value; }
        }

        private int _id;
        private IList _orderedProducts;
    }

BaggaDonuts · **Joined:** Wed Jul 25, 2007 2:16 pm **Posts:** 8

I fixed my issue here. I didn't realize that you must include back ticks around the index column instead of brackets. brackets causes nhibernate to fail miserably.

karlchu · **Posted:** Wed Jul 25, 2007 4:30 pm

Glad it worked for you.