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dynamically loading fields from table

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greenberg.d

Post subject: dynamically loading fields from table

Posted: Fri Dec 16, 2005 3:09 pm

Newbie

Joined: Fri Dec 16, 2005 2:05 pm
Posts: 3

Hi,

I am looking to dynamically load the data for the entire record shown below without actually specifying each property in the mapping XML file. This is a requirement of the program that I am writing, as the Hibernate code must work without configuration modification if columns are added to or take out of the database. Is this possible?

I noticed that there was at one point an XML element named "dynamic-class" that was taken out of the DTD. Did this have anything to do with what I am looking to do?

The hibername.default_entity_mode for the SessionFactory is set to "dynamic-map".

Also, I apologize if I did not get the terminology correct. I am fairly new to Hibernate.

Thank you.

Hibernate version: 3.0.5

Mapping documents:

Code:

<?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 package="mypackage">

        <class table="position" entity-name="DEFAULT" lazy="false">
                <composite-id name="key" class="maypackage.MyKeyClass">
                        <key-property name="col1" />
                        <key-property name="col2" />
                </composite-id>
                <!-- It works with the following line uncommented: -->
                <!-- <property name="col3" type="string" /> -->
        </class>

</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():

Code:

Map m = new HashMap();
m.put("col1", col1Value);
m.put("col2", col2Value);
Map p = (Map) session.load("DEFAULT", (Serializable) m);
System.out.println("This should not be null: " + p.get("col3"));

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anandbn

Post subject:

Posted: Mon Dec 19, 2005 12:49 am

Regular

Joined: Wed May 05, 2004 3:41 pm
Posts: 118
Location: New Jersey,USA

Look at the Java API Doc for "org.hibernate.cfg.Configuration". It provides some hooks to via the "createMappings" method that should probably help you programatically configure your mappings.

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greenberg.d

Post subject: Post subject: dynamically loading fields from table

Posted: Mon Dec 19, 2005 10:32 am

Newbie

Joined: Fri Dec 16, 2005 2:05 pm
Posts: 3

Thank you for your reply.

I read through the API, but it seems that I am missing something. Ideally, I would like a one-line solution similar to the following:

Code:

I understand that there is probably a good reason if this is not part of Hibernate's functionaliy, but is there another way to do this? It could be in code, SessionFactory configuration settings, or mapping XML. It would seem to me to be logical for this type of setting to be outside of code.

Perhaps there is a way to set Hibernate to default to adding all columns in a table rather than just those specified?

Thank you again for helping me.

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greenberg.d

Post subject: dynamically loading fields from table

Posted: Tue Dec 20, 2005 1:46 pm

Newbie

Joined: Fri Dec 16, 2005 2:05 pm
Posts: 3

I just attempted to use this as a possible solution:

Code:

This naturally did not work, as it tried to generate SQL similar to:

Code:

select default0_.col1 as col10_, default0_.col2 as col20_, default0_.* as default0_ ...

Am I at all on the right path?

Thank you.

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