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Brannor McThife

Post subject: Multiple 1-to-1's ending in 1-to-M and Foreign

Posted: Fri Nov 14, 2003 6:22 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

Hey guys, firstly, this isn't a "GIVF ANSWER NOW!!11" type question, but more a.."Is this actually supported?" type discussion.

I'll post the bare basics of my mappings below, and then discuss it.

XML:

Code:

<class name="cdl.impl.XMLImpl" table="XML">
    <id name="XMLID" column="XMLID" type ="java.lang.Long" unsaved-value="null">
        <generator class="identity"/>
    </id>

    <one-to-one name="Matter" class="cdl.impl.MatterImpl" cascade="all"/>

Matter:

Code:

<class name="cdl.impl.MatterImpl" table="Matter">
    <id name="XMLID" column="XMLID" type ="java.lang.Long" unsaved-value="null">
        <generator class="foreign">
            <param name="property">XML</param>
        </generator>
    </id>

    <one-to-one name="XML" class="cdl.impl.XMLImpl" constrained="true"/>
    <one-to-one name="Properties" class="cdl.impl.PropertiesImpl" />

Properties:

Code:

    <class name="cdl.impl.PropertiesImpl" table="Properties">
            <id name="XMLID" column="XMLID" type ="java.lang.Long" unsaved-value="null">
                <generator class="foreign">
                    <param name="property">Matter</param>
                </generator>
            </id>

            <one-to-one name="Matter" class="cdl.impl.MatterImpl" constrained="true"/>
        <bag name="Property" inverse="true" lazy ="false">
            <key column="XMLID" />
            <one-to-many class="cdl.impl.PropertyImpl" />
        </bag>
    </class>

Property:

Code:

<class name="cdl.impl.PropertyImpl" table="Property">
    <id name="PropertyID" column="PropertyID" type ="java.lang.Long" unsaved-value="null">
        <generator class="identity"/>
    </id>

    <property name="XMLID" column="XMLID" not-null="true"/>

Ok, so what we have there, is a 1-1, then another 1-1, then a 1-M.

As you can see, I do the cascade="all" at the first 1-1, but I cannot (can I?) do the cascade from there onwards. When I designed this originally, I switched the cascades on all the way through, but I started getting the null foreign key exception right at the bottom.

I tried many various things, but could never get the cascade to work all the way down. Te question is, does Hibernate support having multiple layers of Foreign key generators, including a bag (set) at the end?

This is a very unique situation for me, and I got it to work perfectly, by doing the child.setParent() way after the first cascade had saved.

As I said, just a discussion, my system works, but it would be nice to work out a way of making cascade work through multiple layers of Foreign generators. :)

-G

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gavin

Post subject:

Posted: Fri Nov 14, 2003 7:34 am

Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia

It should work the only doubt I have is how the "foreign" generator affects things.

I have never tried to use two layers of foreign generators before so I couldn't really say if it works.

Would you please do some further experiments with this and find out? What happens if you try to use "assigned" ids on all classes, for example?

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 7:51 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

Hey Gavin, thanks for answerring, here's a little of how I handle the code...
(I read this in from an XML file, using JAXB)

Code:

matter = xml.getMatter();
Properties props = matter.getProperties();
List properties = props.getProperty();  //yes yes, confusing names... :P

// I then traverse the properties list manipulation various fields, till I get to here:

    property.setProperties(props);
    properties.set(i, property);  //create Child - Parent link
}
props.setProperty(properties);
matter.setProperties(props);

// after other child processing I get to this (probably redundant) bit of code
matter.setXML(xml);
xml.setMatter(matter);

session.saveOrUpdate(xml);
//...

// Then I do this:
    props = matter.getProperties();
    props.setXMLID(matter.getXMLID());
    for (int i=0; i < props.getProperty().size(); i++) {
        property = (Property) props.getProperty().get(i);
        property.setXMLID(matter.getXMLID());
        props.getProperty().set(i, property);
        property.setProperties(props);
        session.save(property);
    }
    props.setMatter(matter);
    matter.setProperties(props);
    session.save(props);

What is interesting, is that even though I have not put in cascade="all", when I save the Properties, it saves all its children.

I did try multiple ways of doing this...the very first version made use of 1-M, 1-M, but then an issue arose, that required a bridging 1-1 inbetween.

I must say, that my gut feeling is that two+ layered foreign generators don't work. I think I'll write a simplified verson of this to test completely, thoroughly, and utterly. :)

I'm modify my live code (assigned) quickly, and see what it does...I'll let you know when I have a result. Surely using assigned would break the one-to-one mapping?

-G

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 7:53 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

Ignore the "What is interesting..." line... :P

-G

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gavin

Post subject:

Posted: Fri Nov 14, 2003 8:04 am

Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia

Quote:

Surely using assigned would break the one-to-one mapping?

Not if you assign the same ids :)

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 8:11 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

gavin wrote:

Quote:

Surely using assigned would break the one-to-one mapping?

Not if you assign the same ids :)

Ok. Next question, doesn't this make the cascade somewhat useless?
Because I will still have to traverse through each of the children, and assign it its PK (ID) and all it will do is mean that I leave out the individual saves. Sure, it'll cascade, but it's not "true" one-to-one cascading is it? :)

I'm creating a much simpler version if it (leaving out all other fields) and I'll test it soon.

-G

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gavin

Post subject:

Posted: Fri Nov 14, 2003 8:26 am

Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia

Quote:

Ok. Next question, doesn't this make the cascade somewhat useless?

Sure, but we are just trying to isolate the problem here!

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 9:00 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

gavin wrote:

Sure, but we are just trying to isolate the problem here!

:D

Ok, here's the exception if I turn cascade="all" on in all the levels:

Code:

java.lang.NullPointerException: attempted to save null
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:582)
        at net.sf.hibernate.id.ForeignGenerator.generate(ForeignGenerator.java:35)
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:601)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1187)
        at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:77)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:234)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:302)
        at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:741)
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:607)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1187)
        at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:77)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:234)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:302)
        at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:741)
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:607)
        at XSDMain.doPartyMatter(XSDMain.java:826)
        at XSDMain.saveXML(XSDMain.java:63)
        at XSDMain.xsd(XSDMain.java:1143)
        at XSDMain.xsd(XSDMain.java:1111)
        at Transform.xmlTransform(Transform.java:49)
        at ProcessXML.storeXML(ProcessXML.java:70)
        at ProcessXML.main(ProcessXML.java:99)

Notice how the ForeignGenerator only actually kicks in when it gets to the lowest level.

Anyway. I'll change it to do everything assigned, and get you feedback soon.

-G

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gavin

Post subject:

Posted: Fri Nov 14, 2003 9:04 am

Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia

Are you sure you actually fully create the association in both directions? looks like the property is null, instead of pointing to the parent.

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 9:10 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

Ok...I seem to hit a little snag with "assigned"...

Code:

12207 [main] ERROR util.JDBCExceptionReporter  - Could not insert
java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]INSERT statement conflicted with COLUMN FOR
EIGN KEY constraint 'FK_Property_XML'. The conflict occurred in database 'CDL', table 'XML', column 'XMLID'.
        at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
        at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
        at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source)
        at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source)
        at com.microsoft.jdbc.sqlserver.tds.TDSRPCRequest.processReplyToken(Unknown Source)
        at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source)
        at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.getNextResultType(Unknown Source)
        at com.microsoft.jdbc.base.BaseStatement.commonTransitionToState(Unknown Source)
        at com.microsoft.jdbc.base.BaseStatement.postImplExecute(Unknown Source)
        at com.microsoft.jdbc.base.BasePreparedStatement.postImplExecute(Unknown Source)
        at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source)
        at com.microsoft.jdbc.base.BaseStatement.executeUpdateInternal(Unknown Source)
        at com.microsoft.jdbc.base.BasePreparedStatement.executeUpdate(Unknown Source)
        at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:472)
        at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:719)
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:607)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1187)
        at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:77)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:234)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:268)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:302)
        at net.sf.hibernate.impl.SessionImpl.doUpdate(SessionImpl.java:1285)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1191)
        at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:77)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:234)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:302)
        at net.sf.hibernate.impl.SessionImpl.doUpdate(SessionImpl.java:1285)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1191)
        at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:77)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:234)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:302)
        at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:741)
        at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:607)
        at XSDMain.doPartyMatter(XSDMain.java:826)
        at XSDMain.saveXML(XSDMain.java:63)
        at XSDMain.xsd(XSDMain.java:1143)
        at XSDMain.xsd(XSDMain.java:1111)
        at Transform.xmlTransform(Transform.java:49)
        at ProcessXML.storeXML(ProcessXML.java:70)

From that trace, it appears to want to save a new XML, then do an Update on Matter (doesn't exist), then an update on Properties (doesn't exist), then save on Property (but the FK reference to Properties cannot be null...)

Any thoughts on that?

-G

PS.
(Just read your post...while I was writing this)
Remember, I still create the links:

Code:

    property.setProperties(props);
    properties.set(i, property);
}
props.setProperty(properties);
matter.setProperties(props);

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 9:13 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

On the "constraint 'FK_Property_XML'", this refers to the DB foreign keys...all tables have XMLID in them...so the FK rules all go from XML to whichever other table....just so you don't think it's a weird rule. :)

-G

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gavin

Post subject:

Posted: Fri Nov 14, 2003 9:47 am

Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia

remember you can't use unsaved-value="null" with assigned ids. You must set unsaved-value="any"

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 10:03 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

gavin wrote:

remember you can't use unsaved-value="null" with assigned ids. You must set unsaved-value="any"

Oops, yeah, sorry, forgot that one. :P

Ok, here are current mappings:

Code:

        <class name="cdl.impl.XMLImpl" table="XML">
            <id name="XMLID" column="XMLID" type ="java.lang.Long" unsaved-value="any">
                <generator class="assigned"/>
            </id>
                <one-to-one name="Matter" class="cdl.impl.MatterImpl" cascade="all"/>
 

Code:

        <class name="cdl.impl.MatterImpl" table="Matter">
            <id name="XMLID" column="XMLID" type ="java.lang.Long" unsaved-value="any">
                <generator class="assigned">
                    <param name="property">XML</param>
                </generator>
            </id>
            <one-to-one name="Properties" class="cdl.impl.PropertiesImpl" cascade ="all" />
            <one-to-one name="XML" class="cdl.impl.XMLImpl" constrained="true"/>

Code:

    <class name="cdl.impl.PropertiesImpl" table="Properties">
            <id name="XMLID" column="XMLID" type ="java.lang.Long" unsaved-value="any">
                <generator class="assigned">
                    <param name="property">Matter</param>
                </generator>
            </id>
            <one-to-one name="Matter" class="cdl.impl.MatterImpl" constrained="true"/>
        <bag name="Property" inverse="true" lazy="false" cascade="all">
            <key column="XMLID" />
            <one-to-many class="cdl.impl.PropertyImpl" />
        </bag>
    </class>

Code:

    <class name="cdl.impl.PropertyImpl" table="Property">
        <id name="PropertyID" column="PropertyID" type ="java.lang.Long" unsaved-value="null">
            <generator class="identity"/>
        </id>
        <many-to-one name="Properties" class="cdl.impl.PropertiesImpl" column="XMLID" not-null="true" />

With this, it throws an exception:

Code:

java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]Cannot insert the value NULL into column 'X
MLID', table 'CDL.dbo.Property'; column does not allow nulls. INSERT fails.

Code:

            Long newID = new Long(100);
            xml.setXMLID(newID);
            xml.getMatter().setXMLID(xml.getXMLID());
            xml.getMatter().getProperties().setXMLID(xml.getXMLID());
            for (int i=0; i < xml.getMatter().getProperties().getProperty().size(); i++) {
                ((Property)xml.getMatter().getProperties().getProperty().get(i)).setXMLID(xml.getXMLID());
// and I've tried this too:
//                 ((Property)xml.getMatter().getProperties().getProperty().get(i)).setProperties(xml.getMatter().getProperties());
// But it throws the same exception
            }
            session.save(xml);

(remember, I DO set the child.setParent()'s elsewhere)

As I said, this is an investigation, because the system works, so if you have other stuff to work on, please don't kill yourself over this. :)

-G

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gavin

Post subject:

Posted: Fri Nov 14, 2003 10:11 am

Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia

Don't mix "identity" generation strategy with other strategies. It means that the PropertyImpl will get inserted first, before the others (which get inserted at flush time).

Use hilo or something for the PropertyImpl

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Brannor McThife

Post subject:

Posted: Fri Nov 14, 2003 10:22 am

Senior

Joined: Tue Sep 23, 2003 8:18 am
Posts: 137
Location: Johannesburg, South Africa

gavin wrote:

Ok, I didn't know that. Something learnt today. :)

I set it to assigned (since I'm only inserting one property for now) and the final cascade worked.

So the mappings are as I posted before, just with the Property generator changed.

We've now established that a full cascade works for multiple 1-1's and a final 1-M, if we don't use Foreign, or Identity, just lots of Assigned.

What now? :)

-G

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