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ruby
 Post subject: Schema export: relation table created without primary key
PostPosted: Wed Feb 01, 2006 6:38 am 
Newbie

Joined: Wed Feb 01, 2006 6:17 am
Posts: 11
Hibernate version: 1.0.2
Name and version of the database you are using: SQL Server 2000

When I create the DB using SchemaExport 3 tables are generated:
tUser (with ID PK), tOrder (with ID PK) and rOrderToUser (relation table between order and user). However the relation table rOrderToUser is created without the desired PK (UserID + OrderID).
I guess my mapping is incorrect, and I should use <composite-id>, but I couldn't figure out the right way of doing it. Any help would be appreciated.
Ruby


User Mapping File:
Code:
  <class name="TestNameSpace.User, impl" table="tUser">
    <id name="Id" type="Int32" column="ID">
      <generator class="assigned" />
    </id>
    <property name="Name" column="Name" type="String" />
    <bag name="Orders" table="rOrderToUser">
      <key column="UserID" />
      <many-to-many column="OrderID" class="TestNameSpace.Order, impl" />
    </bag>
  </class>



Order Mapping File:
Code:
  <class name="TestNameSpace.Order, impl" table="tOrder">
    <id name="Id" type="Int32" column="ID">
      <generator class="assigned" />
    </id>
    <property name="Price" column="Price" type="String" />
    <bag name="Users" table="rOrderToUser" inverse="true">
      <key column="OrderID" />
      <many-to-many column="UserID" class="TestNameSpace.User, impl" />
    </bag>
  </class>
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gert
 Post subject: Re: Schema export: relation table created without primary ke
PostPosted: Wed Feb 01, 2006 7:03 am 
Expert
Expert

Joined: Thu Jan 19, 2006 4:29 pm
Posts: 348
ruby wrote:
When I create the DB using SchemaExport 3 tables are generated:
tUser (with ID PK), tOrder (with ID PK) and rOrderToUser (relation table between order and user). However the relation table rOrderToUser is created without the desired PK (UserID + OrderID).
I guess my mapping is incorrect, and I should use <composite-id>, but I couldn't figure out the right way of doing it. Any help would be appreciated.

Code:
  <bag name="Orders" table="rOrderToUser">
      <key column="UserID" />
      <many-to-many column="OrderID" class="TestNameSpace.Order, impl" />
    </bag>

AFAIK, the bag can contain one element multiple times so the generated schema is correct. The set has "element-only-once" semantic...

Gert
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ruby
 Post subject: Schema export: relation table without primary key (Solved)
PostPosted: Wed Feb 01, 2006 1:53 pm 
Newbie

Joined: Wed Feb 01, 2006 6:17 am
Posts: 11
Gert, Thank you very much.
Using <set> instead of <bag> did the trick.
Ruby
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ruby
 Post subject:
PostPosted: Wed Feb 01, 2006 3:54 pm 
Newbie

Joined: Wed Feb 01, 2006 6:17 am
Posts: 11
Hi again,
A new problem came up:
after using <set> instead of <bag> I can't save an order:

Code:
Code:
Order order = new Order();
order.Price = 100.0;
ISession session = sessionFactory.OpenSession();
session.Save(order);
session.Close();


Exception:
Quote:
Could not save object
Specified cast is not valid.
at NHibernate.Type.SetType.Wrap(ISessionImplementor session, Object collection)
at NHibernate.Impl.WrapVisitor.ProcessArrayOrNewCollection(Object collection, PersistentCollectionType collectionType)
at NHibernate.Impl.WrapVisitor.ProcessCollection(Object collection, PersistentCollectionType collectionType)
at NHibernate.Impl.AbstractVisitor.ProcessValue(Object value, IType type)
at NHibernate.Impl.WrapVisitor.ProcessValues(Object[] values, IType[] types)
at NHibernate.Impl.SessionImpl.DoSave(Object theObj, Key key, IClassPersister persister, Boolean replicate, Boolean useIdentityColumn, CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.DoSave(Object obj, Object id, IClassPersister persister, Boolean useIdentityColumn, CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.SaveWithGeneratedIdentifier(Object obj, CascadingAction action, Object anything)



Using <bag> instead of <set> in order mapping (see below) works fine but when creating the DB using SchemaExport, the relation table rOrderToUser is created without the desired PK (UserID + OrderID).
Any ideas regarding the cast exception?
Ruby

Order Mapping:
Code:
  <class name="TestNameSpace.Order, impl" table="tOrder">
    <id name="Id" type="Int32" column="ID">
      <generator class="assigned" />
    </id>
    <property name="Price" column="Price" type="Double" />
    <set name="Users" table="rOrderToUser" inverse="false">
      <key column="OrderID" />
      <many-to-many column="UserID" class="TestNameSpace.User, impl" />
    </set>
  </class>


User Mapping:
Code:
  <class name="TestNameSpace.User, impl" table="tUser">
    <id name="Id" type="Int32" column="ID">
      <generator class="assigned" />
    </id>
    <property name="Name" column="Name" type="String" />
  </class>
[/code]
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gert
 Post subject:
PostPosted: Wed Feb 01, 2006 4:54 pm 
Expert
Expert

Joined: Thu Jan 19, 2006 4:29 pm
Posts: 348
ruby wrote:
Hi again,
A new problem came up:
after using <set> instead of <bag> I can't save an order:


What is the type of property? For <set>, it should be Iesi.Collections.ISet or System.Collections.ICollection

Gert
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ruby
 Post subject:
PostPosted: Wed Feb 01, 2006 7:05 pm 
Newbie

Joined: Wed Feb 01, 2006 6:17 am
Posts: 11
It is of type ArrayList (System.Collections.ICollection):

Code:
namespace TestNameSpace
{
   public class Order
   {
      private Int32 id;
      private Double price;
      private IList users = new ArrayList();

      public Int32 Id
      {
         get { return id; }
         set { id = value; }
      }

      public double Price
      {
         get { return price; }
         set { price = value; }
      }

      public IList Users
      {
         get { return users; }
         set { users = value; }
      }
   }
}
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gert
 Post subject:
PostPosted: Thu Feb 02, 2006 1:55 am 
Expert
Expert

Joined: Thu Jan 19, 2006 4:29 pm
Posts: 348
ruby wrote:
It is of type ArrayList (System.Collections.ICollection):

Code:
      private IList users = new ArrayList();
      public IList Users
      {
         get { return users; }
         set { users = value; }
      }


Well, currection: You have its type of IList. Try to chnage it
public ICollection Users {get; set; }
or event better
public ISet Users {get; set; }

You should also use Iesi.Collections.HashedSet as class: When restoring set from datavase the NHibernmate will create an class equivalent to that.

Gert
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ruby
 Post subject:
PostPosted: Thu Feb 02, 2006 3:26 am 
Newbie

Joined: Wed Feb 01, 2006 6:17 am
Posts: 11
These declerations cause the exception:
Code:
private ICollection users = new ArrayList();
public ICollection Users
      {
         get { return users; }
         set { users = value; }
      }


private IList users = new ArrayList();
public IList Users
      {
         get { return users; }
         set { users = value; }
      }



These declerations work fine:
Code:
private ISet users = new ListSet();
public ISet Users
      {
         get { return users; }
         set { users = value; }
      }


private ISet users = new HashedSet();
public ISet Users
      {
         get { return users; }
         set { users = value; }
      }



So when using <set> I can't use ICollection instances (i.e. ArrayList) and must use ISet objects (i.e. ListSet) . But when using <bag> I can use ICollection instances. This behaviour is quite problematic as I see it. Any thoughts?
Ruby
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gert
 Post subject:
PostPosted: Thu Feb 02, 2006 3:33 am 
Expert
Expert

Joined: Thu Jan 19, 2006 4:29 pm
Posts: 348
ruby wrote:
So when using <set> I can't use ICollection instances (i.e. ArrayList) and must use ISet objects (i.e. ListSet) . But when using <bag> I can use ICollection instances. This behaviour is quite problematic as I see it. Any thoughts?


You could try one more combination:
Code:
private ICollection users = new HashedSet();
public ICollection Users
      {
         get { return users; }
         set { users = value; }
      }



Anyway, if You require element-once-in-collection behaviour then it is better to use Set instance - so You can not add an element twice to collection accidentially.

Gert
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ruby
 Post subject:
PostPosted: Thu Feb 02, 2006 4:23 am 
Newbie

Joined: Wed Feb 01, 2006 6:17 am
Posts: 11
Thanks Gert, it works now.

So the solution is:

User mapping:
Code:
  <class name="TestNameSpace.User, impl" table="tUser">
    <id name="Id" type="Int32" column="ID">
      <generator class="native" />
    </id>
    <property name="Name" column="Name" type="String" />
  </class>


Order mapping:
Code:
<class name="TestNameSpace.Order, impl" table="tOrder">
    <id name="Id" type="Int32" column="ID">
      <generator class="native" />
    </id>
    <property name="Price" column="Price" type="Double" />
    <set name="Users" table="rOrderToUser" cascade="all" inverse="false">
      <key column="OrderID" />
      <many-to-many column="UserID" class="TestNameSpace.User, impl" />
    </set>
  </class>


User class:
Code:
namespace TestNameSpace
{
   public class User
   {
      private Int32 id;
      private String name;

      public Int32 Id
      {
         get { return id; }
         set { id = value; }
      }

      public String Name
      {
         get { return name; }
         set { name = value; }
      }
   }
}

Order Class:
Code:
namespace TestNameSpace
{
   public class Order
   {
      private Int32 id;
      private Double price;
      private ICollection users = new HashedSet();

      public Int32 Id
      {
         get { return id; }
         set { id = value; }
      }

      public double Price
      {
         get { return price; }
         set { price = value; }
      }

      public ICollection Users
      {
         get { return users; }
         set { users = value; }
      }
   }
}


Test Flow:
Code:
Order order = new Order();
order.Price = 100.0;
User user = new User();
user.Name = "MyName";
((HashedSet)order.Users).Add(user);
ISession session = sessionFactory.OpenSession();
ITransaction transaction = session.BeginTransaction();
session.Save(order);
transaction.Commit();
session.Close();


DB created with all desiered PKs and data saved to all tables in DB.
Thanks again
Ruby.
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