Hibernate Problem Not Saving to database

Question

I am getting a hibernate problem. I am trying with no success. I have a schema where there are Category,Attribute,AttributeOption. e.g. a category can be a 'computer', and its respective attribute can be 'RAM','Hard Disk' and e.g. 'RAM' can have attribute option '512MB','1024MB' When I try the above schema with hibernate everything is OK.

Now I have one other requirement. A 'Category' can have many sub categories. e.g. a 'Computer' can have 'laptop' or 'Notebook' as sub categories. Now these subcategories are of the class Category themselves

then I get this scheme:

        1. Category  ------>Category
           A category can contain many sub categories
           e.g. A computer can be a notebook or laptop

        2. Category ------>Attribure
           A category can have many attribute
           A  notebook can have RAM , Hard Disk, Screen Size

        3. Attribute  ------>AttributeOption
           An Attribute can have many attribute options
           e.g. RAM can be 512 MB, 1024 MB

These are my classes without their getters and setters

Class Category:
public class Category implements IsSerializable 
{
    private long CategoryId;
    private String CategoryName;
    private Set <Category> SubCategory=new HashSet <Category> ();
    private Set <Attribute> AllAttributes= new HashSet  <Attribute>();

}
Category Mapping File:


 <?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Dec 16, 2010 8:07:32 AM by Hibernate Tools 3.4.0.Beta1 -->
<hibernate-mapping>
    <class name="com.BiddingSystem.Models.Category" table="CATEGORY">
        <id name="CategoryId" type="long">
            <column name="CATEGORYID" />
            <generator class="native" />
        </id>
        <property name="CategoryName" type="java.lang.String">
            <column name="CATEGORYNAME" />
        </property>
        <many-to-one name="ParentCategory" class="com.BiddingSystem.Models.Category">
            <column name="PARENTCATEGORYID" />
        </many-to-one>
        <set name="SubCategory" inverse="true" lazy="true" cascade="all" fetch="join">
            <key>
                <column name="PARENTCATEGORYID" />
            </key>
            <one-to-many class="com.BiddingSystem.Models.Category" />
        </set>
        <set name="AllAttributes" table="ATTRIBUTE" inverse="false" lazy="true">
            <key>
                <column name="CATEGORYID" />
            </key>
            <one-to-many class="com.BiddingSystem.Models.Attribute" />
        </set>
    </class>
</hibernate-mapping>


Class Attribute:
public class Attribute 
{
    private long AttributeId;
    private String AttributeName;
    private Set <AttributeOption> Options= new HashSet <AttributeOption>();
}

Attribute Mapping File:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Dec 16, 2010 5:25:09 AM by Hibernate Tools 3.4.0.Beta1 -->
<hibernate-mapping>
    <class name="com.BiddingSystem.Models.Attribute" table="ATTRIBUTE">
        <id name="AttributeId" type="long">
            <column name="ATTRIBUTEID" />
            <generator class="native" />
        </id>
        <property name="AttributeName" type="java.lang.String">
            <column name="ATTRIBUTENAME" />
        </property>
        <set name="Options" table="ATTRIBUTEOPTION" inverse="false"  cascade="all">
            <key>
                <column name="ATTRIBUTEID" />
            </key>
            <one-to-many class="com.BiddingSystem.Models.AttributeOption" />
        </set>
    </class>
</hibernate-mapping>


Class AttributeOption:
public class AttributeOption 
{
    private long AttributeOptionId;
    private String Option;
    private String SQLValue;
}
Attribute Mapping File:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Dec 16, 2010 5:25:09 AM by Hibernate Tools 3.4.0.Beta1 -->
<hibernate-mapping>
    <class name="com.BiddingSystem.Models.AttributeOption" table="ATTRIBUTEOPTION">
        <id name="AttributeOptionId" type="long">
            <column name="ATTRIBUTEOPTIONID" />
            <generator class="native" />
        </id>
        <property name="Option" type="java.lang.String">
            <column name="OPTION" />
        </property>
        <property name="SQLValue" type="java.lang.String">
            <column name="SQLVALUE" />
        </property>
    </class>
</hibernate-mapping>

I am trying the following. I am not getting any error but It is not saving the 'Laptop' which is a category of 'computer' else everything is being saved. So i think the problem is with this part from the category mapping file:

<set name="SubCategory" table="CATEGORY" cascade="all">
            <key>
                <column name="CATEGORYID" />
            </key>
            <one-to-many class="com.BiddingSystem.Models.Category" />
        </set>



This is part of my program  


    Category C=new Category();
    C.setCategoryName("Computer");
    AttributeOption R512= new AttributeOption();R512.setOption("512");R512.setSQLValue("512");
    AttributeOption R1024= new AttributeOption();R1024.setOption("1024");R1024.setSQLValue("1024");


        Category C0= new Category();
    C0.setCategoryName("Laptop");

    C.getSubCategory().add(C0);

    Attribute RAM= new Attribute();
    RAM.setAttributeName("RAM");

    RAM.getOptions().add(R512);RAM.getOptions().add(R1024);

    C.getAllAttributes().add(RAM);



    Transaction tx = null;
    try
    {
        tx=session.beginTransaction();
        tx.begin();
        session.saveOrUpdate(C);
        tx.commit();
        return true;
    }
    catch (Exception e)
    {
        tx.rollback();
        e.printStackTrace();
        return false;
    }

jpkroehling · Accepted Answer · 2010-12-16 15:07:18Z

1

Something seems wrong with this:

C0.getSubCategory().add(C0);

Shouldn't it be:

C.getSubCategory().add(C0);

answered Dec 16, 2010 at 15:07

jpkroehling

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5 Comments

jpkroehling Over a year ago

One extra comment: note that in OO programming, the link between two objects is a one-way link, while in relational models it's two way link (you can navigate through the relationship from both sides). So, in this case, it seems that the parents contains a set of subcategories, but the category doesn't know anything about it's parent. Usually, it's a good idea to set both sides of the relationship. See this example from Hibernate test suite: github.com/hibernate/hibernate-core/blob/master/hibernate-core/…

jpkroehling Over a year ago

Actually, this is an even better example, as it uses a reference to an object of the same class: github.com/hibernate/hibernate-core/blob/master/hibernate-core/…

Noor Over a year ago

I have a new mapping file. My problem now is that there are no link between parent category and child category

jpkroehling Over a year ago

What do you mean? No link in code, or in the database? If in the database, you mean that "parent_id" is null?

jpkroehling Over a year ago

By looking at your code, it seems you forgot the other side of the link: C0.setParentCategory(C);

Olivier Croisier · Accepted Answer · 2010-12-16 15:06:00Z

0

Hummm, I see some place for improvement in this code : First, you should use the persist() method to persist your entities. Second, to persist a whole object graph, you must either a) persist the sub-objects manually, then the "main" object ; or b) use the Cascade parameter on your relationships so that persisting the "main" object also triggers the persistence of the related sub-objects.

You can find more info on cascading here : http://docs.jboss.org/hibernate/stable/core/reference/en/html/example-parentchild.html#example-parentchild-cascades

answered Dec 16, 2010 at 15:06

Olivier Croisier

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1 Comment

Noor Over a year ago

Ya, I have placed cascade every where to prevent manual saving to the database

Noor · Accepted Answer · 2010-12-16 16:43:33Z

Ok, I made it to work

The key to it is the category mapping file:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Dec 16, 2010 8:37:02 AM by Hibernate Tools 3.4.0.Beta1 -->
<hibernate-mapping>
    <class name="com.BiddingSystem.Models.Category" table="CATEGORY">
        <id name="CategoryId" type="long">
            <column name="CATEGORYID" />
            <generator class="native" />
        </id>
        <property name="CategoryName" type="java.lang.String">
            <column name="CATEGORYNAME" />
        </property>

        <many-to-one name="ParentCategory" class="com.BiddingSystem.Models.Category">
            <column name="PARENT_CATEGORY_ID" />
        </many-to-one>

        <set name="SubCategory" lazy="false" cascade="all-delete-orphan" inverse="true">
            <key>
                <column name="PARENT_CATEGORY_ID" />
            </key>
            <one-to-many class="com.BiddingSystem.Models.Category" />
        </set>

        <set name="AllAttributes" table="ATTRIBUTE" inverse="false" lazy="true">
            <key>
                <column name="CATEGORYID" />
            </key>
            <one-to-many class="com.BiddingSystem.Models.Attribute" />
        </set>
    </class>
</hibernate-mapping>

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