A full object oriented hibernate Entity gives you better results

The importance of object oriented design principles has been again and again by many hibernate gurus, but then also you find designs again and again that are non compliant with OOD. this makes it less possible to make scalable and maintainable applications.

Basically while designing applications you may have 2 different approaches. 1. is start from an available database degsin. 2. build from scratch a full OO System. In both cases the hibernate can help you design applications with reusable components. If you are not using a normalized database then the problem of data duplication begins to haunt you once it is in maintenance phase. here all hibernate can be of good help if you have a good OO Design of entity which will surely help you to reduce efforts in code maintenance.Serious efforts should be made to reduce code duplications of entities. where by you can make sure data is not duplicated in amoung entities. Here i wish to point out a strategy to avoid code duplication based on OO Principle of inheritance which has helped me and is sure to help you.

Imagine you have 2 tables A and B with redundant data where most of the fields except some fields are common due to some reason. In this case you may use inheritance using an abstract parent class and 2 child classes. These child classes can override the properties of the parent if there is any data difference between the siblings. example the Id. and also they may have their own properties in addition. The main advantage of this approach is 1) you have less code to maintain. 2) by using polymorphism you can use the parent to access the child data.
Even though i disagree to the database design that produced such an entity design, i overcame most of the difficulties of the bad database design with the above model The above sitaution can be examplified by the following hbm file.

<hibernate-mapping>

    <class name="AbstractItem" abstract="true">

                          

        <id name="id" column="ID" type="long">

            <generator class="native"/>

        </id>

                     

        <property name="name" column="name" type="string"/>

        <property name="code" column="code" type="string"/>

        <property name="eAN" column="ean" type="string"/>

                          

        <union-subclass name="TempItem" table="temp_item">

            <property name="state" column=”state” type="short"/>

       </union-subclass>

        <union-subclass

           name="ApprovedItem" table="approved_item">

            <property name="approverId" column=”appover_id” type="long"/>

            <property name="pack" column=”pack” type="short"/>

            <property name="dimension" column=”dimesion” type="string"/>

        </union-subclass>

    </class>

</hibernate-mapping>