one-to-one relationship help

j2flk · **Joined:** Wed Feb 25, 2009 5:09 pm **Posts:** 8

Hi,

I'm trying to do a one-to-one mapping relationship between a User and a UserProfile. One user can only have one profile and one profile can only belong to one user. I get the following error when trying to add a new user:

attempted to assign id from null one-to-one property: Users System.Exception {NHibernate.Id.IdentifierGenerationException}

My mapping files are below:

Users.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">

<class name="Users, App_Code/Mappings" lazy="true" table="users">
<id name="UserID" column="user_id" type="Int32">
<generator class="identity">
</generator>
</id>
<property name="FirstName" column="first_name" type="String" length="50"/>
<property name="LastName" column ="last_name" type="String" length="50"/>
<property name="UserName" column ="user_name" type="String" length="50"/>
<property name="EmailAddress" column ="email_address" type="String" length="50"/>
<property name="DOB" column="dob" type="DateTime"/>
<property name="Gender" column="gender" type="boolean"/>
<property name="CreationDate" column="creation_date" type="DateTime"/>
<property name="LastLogin" column="last_login_date" type="DateTime"/>
<property name="Password" column="user_password" type="String" length="100"/>

<many-to-one name="Country" column="country_id" class="Countries, App_Code/Mappings" cascade ="none"/>
<one-to-one name="UsersProfile" class="UsersProfile, App_Code/Mappings" cascade="all"/>

</class>

</hibernate-mapping>

UsersProfile.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">

<class name="UsersProfile, App_Code/Mappings" lazy="true" table="Users_Profile">
<id name="UserID" type="Int32" column="user_id">
<generator class="foreign">
<param name="property">Users</param>
</generator>
</id>
<property name="Website" column="website_url" type="String" length="100"/>
<property name="Occupation" column ="occupation" type="String" length="100"/>
<property name="Hobbies" column="hobbies" type="String" length ="100"/>

<one-to-one name="Users" class="Users, App_Code/Mappings" constrained ="true"/>

</class>

</hibernate-mapping>

My User.cs returns a UserProfile object:

public virtual UsersProfile UsersProfile
{
get { return userProfile; }
set { userProfile = value; }
}

My UsersProfile.cs returns a Users object:

public virtual Users Users
{
get { return _user; }
set { _user = value; }
}

The AddNewUser code is below:

public bool AddNewUser(Users lUser)
{
ISession session = NHibernateHelper.GetCurrentSession();
ITransaction tx = null;
bool success = false;
lUser.UsersProfile = new UsersProfile();
lUser.UsersProfile.UserID = lUser.UserID;
try
{
tx = session.BeginTransaction();
session.Save(lUser);
tx.Commit();
success = true;
}
catch (Exception ex)
{
tx.Rollback();
success = false;
}

return success;

}

So basically what i am attempting to do is when I add a user, i want a user profile to be added with the same id. My user table has a primary key user_id and my userprofile table has a primary and foreign key of user_id.

Hopefully you can help me out...i have spent alot of time trying to figure this one out.

Cheers

wolli · **Posted:** Tue Mar 03, 2009 11:42 am

Try

lUser.UsersProfile.Users = lUser;

instead of

lUser.UsersProfile.UserID = lUser.UserID;

You specified the "Users" property for id generator "foreign". Hibernate then will use this property to get the id and in your case it's null.

j2flk · **Joined:** Wed Feb 25, 2009 5:09 pm **Posts:** 8

thanks..it worked....cheers

racketin · **Joined:** Thu Nov 06, 2008 10:42 am **Posts:** 5

Thx wolli, I was too stuck on the same issue and it worked for me.

But I had to make my one-to-one association bi-directional. Any idea, if I would like to achieve the same thing in unidirectional mapping ie. UserProfile doesnt have User as an attribute.

I assume that foreign key generation requires a property ( in this case "Users") which wouldnt be available in case of uni-directional.

Please help me out..

wolli · **Posted:** Wed Apr 01, 2009 4:48 am

Hmm, not sure. Post your mappings.

racketin · **Joined:** Thu Nov 06, 2008 10:42 am **Posts:** 5

This is relevant mapping for Party Entity.

Code:

@Entity
@Table(name = "PARTY")
public class Party{
   private Person person;
   private String key;
   @OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL,)
    @PrimaryKeyJoinColumn(name = "PARTY_ID", referencedColumnName = "PERSON_PARTY_ID")
    public Person getPerson() {
        return person;
    }
    
    public void setPerson(Person person) {
        this.person = person;
    }

    @Id
    @GeneratedValue(generator = "system-uuid")
    @GenericGenerator(name = "system-uuid", strategy = "uuid")
    @Column(name = "PARTY_ID", nullable = false)
    public String getKey() {
        return key;
    }
    
    private void setKey(String key) {
        this.key = key;
    }
}

and it is one-to-one mapped to Person as:

Code:

@Entity(name = "Person")
@Table(name = "PERSON")
public class Person {

   private String key;
     @Id
     @Column(name = "PERSON_PARTY_ID")
    public String getKey() {
        return key;
    }
    
    public void setKey(String key) {
        this.key = key;
    }
    
}

Now in Person, I deliberately dont have sysUUID as generated as then it generates a unique value for person and the association gets lost. With this mapping hibernate throws the following exception :

Caused by: org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): Person.

-thanks again

wolli · **Posted:** Wed Apr 01, 2009 10:52 am

You probably have to specify the generator "foreign" like j2flk has in his example:

<id name="UserID" type="Int32" column="user_id">
<generator class="foreign">
<param name="property">Users</param>
</generator>
</id>

But, I don't know how to do that with attributes.