createQuery load object where associated relation value=?

gagan090283 · **Joined:** Wed Mar 15, 2006 10:36 am **Posts:** 14

Hi all,

I am a sort of beginner to hibernatre,
and using only XML-Mapping in hibernate mapping file.

If two enties are assciated with each other with one-to-one or one-to-many or many-to-one or many-to-many relationship, eg Parent assciated with children, so I want to load parent where children_id=?, or load the children object where parent_id=?.

To be more specific

I have a Product-User relationship defined as Many-to-Many, and I want to load product which has User as userId=?

Mapping for this
<bag name="productsUsers" table="ProductsUsers" node=".">
<key column="productId" />
<many-to-many entity-name="User" embed-xml="false"
column="userId" node="userId" />
</bag>

or I want to load Product where Bug is bugId=?

mapping for this is:

<bag name="bugsProducts" cascade="all" inverse="true"
node=".">
<key column="productId" />
<one-to-many entity-name="Bug" embed-xml="false"
node="bugId" />
</bag>

I hope I have made my question clear to you..

So is there any othere way to do it, with just specifying entity and relationship value in query.

Thanks in advance..

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I presume that your problem is only when the relationship is unidirectional. Bidirectional is easy. For unidirectional in HQL, use

Code:

select p
from Product p
join p.Bugs b
where b.id = ?

For Criteria, the model is

Code:

Criteria crit = sess.createCriteria(Product.class);
crit.addAlias("Bugs", "b");
crit.add(Restrictions.eq("b.id", bugId);
return (List<Product>) crit.list();

gagan090283 · **Joined:** Wed Mar 15, 2006 10:36 am **Posts:** 14

Hi tenwit

The complete XML look like this.

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class entity-name="Bug" table="Bug" node="bug">
<id name="bugId" column="bugId" node="bugId"
type="java.lang.String">
<generator class="uuid" />
</id>
<version name="version" column="VERSION" node="version" />
<property name="bugInfo" column="bugInfo" node="bugInfo"
type="java.lang.String" length="80" not-null="true" />

<bag name="bugUsers" node="." cascade="all" inverse="true">
<key column="bugId" />
<one-to-many entity-name="User" embed-xml="false"
node="userId" />
</bag>

<many-to-one name="productId" column="productId"
node="productId" embed-xml="false" entity-name="Product" />

</class>

<class entity-name="Product" table="Product" node="product">
<id name="productId" column="productId" node="productId"
type="java.lang.String">
<generator class="uuid" />
</id>
<version name="version" column="VERSION" node="version" />
<property name="productInfo" column="PRODUCT_INFO"
node="productInfo" type="java.lang.String" length="80"
not-null="true" />

<bag name="bugsProducts" cascade="all" inverse="true"
node=".">
<key column="productId" />
<one-to-many entity-name="Bug" embed-xml="false"
node="bugId" />
</bag>

<bag name="productsUsers" table="ProductsUsers" node=".">
<key column="productId" />
<many-to-many entity-name="User" embed-xml="false"
column="userId" node="userId" />
</bag>
</class>

<class entity-name="User" table="USERS" node="user">

<id name="userId" column="userId" node="userId"
type="java.lang.String">
<generator class="uuid" />
</id>

<version name="version" column="VERSION" node="version" />

<property name="email" column="EMAIL" node="email"
type="java.lang.String" length="40" />

<many-to-one name="manager" node="manager" column="managerId"
entity-name="User" embed-xml="false" update="true" />

<many-to-one name="bugId" column="bugId" node="bugId"
embed-xml="false" entity-name="Bug" />

<bag name="productsUsers" node="." table="ProductsUsers" lazy="true"
inverse="true">
<key column="userId" />
<many-to-many entity-name="Product" embed-xml="false"
column="productId" node="productId" />
</bag>

<one-to-one name="userDetails" node="userDetails"
entity-name="UserDetail" embed-xml="false" />
</class>

<class entity-name="UserDetail" table="USER_DETAILS"
node="userDetail">
<id name="userId" column="userId" node="userId"
type="java.lang.String">
<generator class="foreign">
<param name="property">user</param>
</generator>
</id>
<version name="version" column="VERSION" node="version" />

<one-to-one name="user" node="." entity-name="User"
constrained="true" />

<property name="name" column="NAME" node="name"
type="java.lang.String" />
<property name="address" column="ADDRESS" node="address"
type="java.lang.String" />
<property name="phone" column="PHONE" node="phone"
type="java.lang.String" />
</class>

</hibernate-mapping>

My relation is bi-directional, The problem I am facing is, I can't do p.Bug as you said, because Bug is not the property or component of product. Correct me if I am wrong.

Thanks for the reply..

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

The HQL is:

Code:

select p
from Product p
join p.BugsProducts bp
where bp.id = ?

You should be able to figure out the equivalent Criteria from my earlier example.

gagan090283 · **Joined:** Wed Mar 15, 2006 10:36 am **Posts:** 14

Hi tenwit,
It works to some extent, but not exactly how i want.
I am retrieving Product as a Map by opening session in Map mode.
When I do this way, I retrieved a List having objects of Object class, not Map.

When I saw the query, it is also retrieving Bug attributes, How I can avoid that.
Regarding writing criteria, as I earlier mention, I am using only XML mapping, no POJO classes, so there is no Product.class as such. I am not sure that I can use entity_name.class for this.

Please correct me If I am wrong.

Thanks

gagan090283 · **Joined:** Wed Mar 15, 2006 10:36 am **Posts:** 14

Hi tenwit,

My problem is solved..
Thanks a lot..