About the Order-LineItem-Product example

Selector2007 · **Joined:** Tue Jul 29, 2008 10:53 am **Posts:** 11

In the documenation there's an example of a many-to-many relation. But it misses the C# objects.

http://www.hibernate.org/hib_docs/reference/en/html/example-mappings-customerorderproduct.html

Has anyone made this example work?

I've tried it with these C# objects:

Code:

public class Order
{
   public Int64 ID { get; set; }
   public Int CustomerID { get; set; }
   public DateTime Timestamp { get; set; }
   public IList<LineItem> LineItems { get; set; }
}


public class LineItem
{
   public Int64 ID { get; set; }
   public Int OrderID { get; set; }
   public Product OrderdProduct { get; set; }
}

public class Product
{
   public Int64 ID { get; set; }
   public String SerialNumber { get; set; }
}

But somehow I get like thousands of lineItems which are all null, even when I have only a few LineItems in my database.

wolli · **Posted:** Fri Mar 06, 2009 3:16 am

What line_number values do you have in the table ? If they do not start with 0 or if some are missingm (e.g 0,4,5,6,9, ...) , you'll get empty entries in the list.

Selector2007 · **Joined:** Tue Jul 29, 2008 10:53 am **Posts:** 11

I've fixed the problem!

This was the original mapping:

Code:

<class name="Order" table="orders">

     <id name="id">
         <generator class="native"/>
     </id>

     <property name="date"/>

     <many-to-one name="customer" column="customer_id"/>

     <list name="lineItems" table="line_items">
         <key column="order_id"/>

         <list-index column="line_number"/>

         <composite-element class="LineItem">
             <property name="quantity"/>
             <many-to-one name="product" column="product_id"/>
         </composite-element>
     </list>

 </class>

The problem is that the LineItems are mapped as a List. This doesn't work very well. When you change this to a set, and remove the list-index part, everything works fine:

Code:

<class name="Order" table="orders">

     <id name="id">
         <generator class="native"/>
     </id>

     <property name="date"/>

     <many-to-one name="customer" column="customer_id"/>

     <set name="lineItems" table="line_items">
         <key column="order_id"/>

         <composite-element class="LineItem">
             <property name="quantity"/>
             <many-to-one name="product" column="product_id"/>
         </composite-element>
     </set>

 </class>

And this is how the C# object is coded:

public class Order
{
public Int64 ID { get; set; }
public Int CustomerID { get; set; }
public DateTime Timestamp { get; set; }
public Iesi.Collections.Generic.ISet<LineItem> LineItems { get; set; }
}

public class LineItem
{
public Int64 ID { get; set; }
public Int OrderID { get; set; }
public Product OrderdProduct { get; set; }
}

public class Product
{
public Int64 ID { get; set; }
public String SerialNumber { get; set; }
}

Selector2007 · **Joined:** Tue Jul 29, 2008 10:53 am **Posts:** 11

I've fixed the problem!

This was the original mapping:

Code:

<class name="Order" table="orders">

     <id name="id">
         <generator class="native"/>
     </id>

     <property name="date"/>

     <many-to-one name="customer" column="customer_id"/>

     <list name="lineItems" table="line_items">
         <key column="order_id"/>

         <list-index column="line_number"/>

         <composite-element class="LineItem">
             <property name="quantity"/>
             <many-to-one name="product" column="product_id"/>
         </composite-element>
     </list>

 </class>

The problem is that the LineItems are mapped as a List. This doesn't work very well. When you change this to a set, and remove the list-index part, everything works fine:

Code:

<class name="Order" table="orders">

     <id name="id">
         <generator class="native"/>
     </id>

     <property name="date"/>

     <many-to-one name="customer" column="customer_id"/>

     <set name="lineItems" table="line_items">
         <key column="order_id"/>

         <composite-element class="LineItem">
             <property name="quantity"/>
             <many-to-one name="product" column="product_id"/>
         </composite-element>
     </set>

 </class>

And this is how the C# object is coded:

public class Order
{
public Int64 ID { get; set; }
public Int CustomerID { get; set; }
public DateTime Timestamp { get; set; }
public Iesi.Collections.Generic.ISet<LineItem> LineItems { get; set; }
}

public class LineItem
{
public Int64 ID { get; set; }
public Int OrderID { get; set; }
public Product OrderdProduct { get; set; }
}

public class Product
{
public Int64 ID { get; set; }
public String SerialNumber { get; set; }
}

Selector2007 · **Joined:** Tue Jul 29, 2008 10:53 am **Posts:** 11

I've fixed the problem!

This was the original mapping:

Code:

<class name="Order" table="orders">

     <id name="id">
         <generator class="native"/>
     </id>

     <property name="date"/>

     <many-to-one name="customer" column="customer_id"/>

     <list name="lineItems" table="line_items">
         <key column="order_id"/>

         <list-index column="line_number"/>

         <composite-element class="LineItem">
             <property name="quantity"/>
             <many-to-one name="product" column="product_id"/>
         </composite-element>
     </list>

 </class>

The problem is that the LineItems are mapped as a List. This doesn't work very well. When you change this to a set, and remove the list-index part, everything works fine:

Code:

<class name="Order" table="orders">

     <id name="id">
         <generator class="native"/>
     </id>

     <property name="date"/>

     <many-to-one name="customer" column="customer_id"/>

     <set name="lineItems" table="line_items">
         <key column="order_id"/>

         <composite-element class="LineItem">
             <property name="quantity"/>
             <many-to-one name="product" column="product_id"/>
         </composite-element>
     </set>

 </class>

And this is how the C# object is coded:

public class Order
{
public Int64 ID { get; set; }
public Int CustomerID { get; set; }
public DateTime Timestamp { get; set; }
public Iesi.Collections.Generic.ISet<LineItem> LineItems { get; set; }
}

public class LineItem
{
public Int64 ID { get; set; }
public Int OrderID { get; set; }
public Product OrderdProduct { get; set; }
}

public class Product
{
public Int64 ID { get; set; }
public String SerialNumber { get; set; }
}