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Mapping problems, extending questions

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Manny

Post subject: Mapping problems, extending questions

Posted: Tue Sep 19, 2006 9:16 am

Newbie

Joined: Tue Sep 19, 2006 8:50 am
Posts: 7

Hi,

I'm in a bit of a pickle with an relation mapping that I can't get working properly.

--------------------------------------------------------------

one User -----> many Account

one Account ------> one User

AAccount and BAccount extends Account

-----------------------------------------------------------------

* An user can have one AAccount and one BAcount
* One Aaccount/BAccount can only belong to one User

User: one-to-many -> Account
Account: ?

I don't know if the User in Account should be mapped with one-to-one (as only one instance of AAccount or BAccount are 'allowed' in User) or if it is the super class that has an many-to-one (as in this case two Account objects can have relations with the User)

I've almost got this working with
User: many-to-many to account
Account: one-to-one to User
but I'm having problems with getting null objects when trying to access account.getUser(); despite that the database looks correct.

Grateful for any help I can get.

/Manny

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wykoff

Post subject:

Posted: Tue Sep 19, 2006 11:01 am

Beginner

Joined: Thu Aug 24, 2006 6:01 am
Posts: 49
Location: sophia-antipolis, France

Hi Manny,

what you have is:

User: OneToMany to Account
Account: ManyToOne to User

You mustn't use OneToOne on the Account-side.

Here's an example:

I have a ManyToOne relationship between Item and Definition. I have annotated both ends of the relationship:

Code:

class Definition {
    private List<Item> items;

    @OneToMany(mappedBy="definition")
    public List<Item> getItems() {
        return items;
    }
}

class Item {

     private Definition definition;
    @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
    @JoinColumn(name="DEFINITION_ID")
    public Definition getDefinition() {
        return definition;
    }
}

In your case, it's the same with Item = Account and Definition = User.

hope this helps.

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Manny

Post subject:

Posted: Thu Sep 21, 2006 6:17 am

Newbie

Joined: Tue Sep 19, 2006 8:50 am
Posts: 7

Hi wykoff,

thx for pushing me in the right direction. This code worked for me:

User-side:

Code:

...
<set name="accounts" table="accounts" cascade="all" inverse="true">
   <key column="userId" />
   <one-to-many class="model.Account" />
</set>

Account-side:

Code:

<class name="Account" table="account">
   <id name="id" unsaved-value="null">
      <generator class="native"/>
   </id>
   <property name="type" />
   <many-to-one column="userId" name="user" />
      
   <joined-subclass name="model.TestAccount" table="test_account">
      <key column="id" />
      <one-to-one name="cart" cascade="all" />
   </joined-subclass>      
</class>

Still I think that to get an one-to-one working from a subclass would save me the userId column. :)

/Manny

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wykoff

Post subject:

Posted: Fri Sep 22, 2006 11:15 am

Beginner

Joined: Thu Aug 24, 2006 6:01 am
Posts: 49
Location: sophia-antipolis, France

Hi Manny

sorry, but I lost this post. I didn't understand exactly what you wanted before, but I think I understand now. It looks to me like you want something like this:

Code:

class User {
    private List<Account> Accounts;

    @OneToMany(mappedBy="user")
    public List<Account> getAccounts() {
        return Accounts;
    }
}

class abstract Account {

    protected User user;

    @Transient
    public abstract User getUser();
}

class AAccount extends Account {
    @ManyToOne
    public User getUser() {
        return user;
    }
}
class BAccount extends Account {
    @ManyToOne
    public User getUser() {
        return user;
    }
}

I'm sorry, but I don't know how to do the mapping in the config file, but perhaps this will give you the right idea.

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