Hello Craig/everyone,
Craig,
Your suggestion below worked:
>
Lampent, get the fields it needs:SELECT l FROM Lampent lList<Lampent> lampents = allLightingpro();for (Lampent lampent : lampents) { System.out.println( "Lampent pnumb: " + lampent.getPnumb() + ", woltage: " + lampent.getWoltage() + ", manuname: " + lampent.getManufacturerent().getName() );}<
I used the JQPA query as:
@NamedQuery(name ="getAlldetails", query=" SELECT l FROM Lampent l")
in Lampent
and then in my client I added to the get method as follows:
out.println("<TD>");out.println(lampents.getLamManufacturerent().getManuname());out.println("</TD>");
it works. great stuff. Thank you
eve
Date: Wed, 5 Dec 2007 12:23:15 -0800
From: Craig.Russell_at_Sun.COM
To: persistence_at_glassfish.dev.java.net
Subject: Re: question on entity relationships
Hi Eve,First, the StackOverflow is a bug that should never occur based on performing a query. A reproducible test case would help solve this issue.But, let's talk about what you're trying to accomplish. If the caller of this method expects a List<Lampent> it can iterate the List and for each Lampent, get the fields it needs:SELECT l FROM Lampent lList<Lampent> lampents = allLightingpro();for (Lampent lampent : lampents) { System.out.println( "Lampent pnumb: " + lampent.getPnumb() + ", woltage: " + lampent.getWoltage() + ", manuname: " + lampent.getManufacturerent().getName() );}This will query the Lampents and then retrieve the Manufacturerent for each Lampent. But you might only want the fields to be returned, not the Lampent instances. In this case, projecting the fields from Lampent and Manufacturent would be ok, but the return from the query should be List<Object[]> and then you iterate the result: SELECT l.pnumb, l.catergory, l.lwoltage, lm.manuname FROM Lampent l LEFT OUTER JOIN l.lamManufacturerent lmList<Object[ ]> results = allLightingpro();for (Object[ ] obj : results) { System.out.println( "Lampent pnumb: " + obj[0] + ", catergory: " + obj[1] + ", woltage: " + obj[2] + ", manuname: " + obj[3]);}
Regards,CraigOn Dec 5, 2007, at 11:24 AM, Eve Pokua wrote:Hello,
Yes, same msg:
[#|2007-12-05T19:00:44.843+0000|INFO|sun-appserver9.1|javax.enterprise.system.stream.out|_ThreadID=17;_ThreadName=httpSSLWorkerThread-8080-1;|
Can not access DB data|#]
[#|2007-12-05T19:00:53.609+0000|INFO|sun-appserver9.1|javax.enterprise.system.stream.out|_ThreadID=17;_ThreadName=httpSSLWorkerThread-8080-1;|
Can not access DB data|#]
here is the change code:
public List<lightingspecreimp.Lampent> allLightingpro(){
List results=emp.createNamedQuery("getAlldetails").getResultList();
return results;
}
Could it be that I need to make changes to my toString method of my Lampent:
public String toString()
{String s= pnumb + " " + catergory + " " + lwoltage + " " + lamManufacturerent ;
return s;}
or even, the get and set methods in Lampent relating to lamManufacturerent :
public LamManufacturerent getLamManufacturerent()
{return lamManufacturerent;}
public void setLamManufacturerent(LamManufacturerent lamManufacturerent)
{this.lamManufacturerent=lamManufacturerent;}
The above get method means it will return an object of lamManufacturerent not fields.
So how do I get fields of lamManufacturerent from Lampent?
Thanks
eve
Date: Tue, 4 Dec 2007 15:07:54 -0800
From: Craig.Russell_at_Sun.COM
To: persistence_at_glassfish.dev.java.net
Subject: Re: question on entity relationships
Hi eve,The return type of the query should not be List<Lampent> since you're not returning Lampent instances, just a bunch of fields.Do you get the same exception if you do:List results=emp.createNamedQuery("getAlldetails").getResultList();Craig
On Dec 4, 2007, at 3:01 PM, Eve Pokua wrote:Hello,
I have checked this and made changes to this:
@NamedQuery(name ="getAlldetails", query=" SELECT l.pnumb, l.catergory, l.lwoltage, lm.manuname FROM Lampent l LEFT OUTER JOIN l.lamManufacturerent lm")
I am still not able to retreive data. error msg:
[#|2007-12-04T22:51:10.754+0000|INFO|sun-appserver9.1|oracle.toplink.essentials.session.file:/C:/Sun/SDK2/domains/domain1/applications/j2ee-apps/LIGHTINGSPEC/LIGHTINGSPEC-ejb_jar/-LIGHTINGSPEC-ejbPU3|_ThreadID=19;_ThreadName=httpSSLWorkerThread-8080-1;|file:/C:/Sun/SDK2/domains/domain1/applications/j2ee-apps/LIGHTINGSPEC/LIGHTINGSPEC-ejb_jar/-LIGHTINGSPEC-ejbPU3 login successful|#]
[#|2007-12-04T22:51:11.234+0000|INFO|sun-appserver9.1|javax.enterprise.system.stream.out|_ThreadID=19;_ThreadName=httpSSLWorkerThread-8080-1;|
Can not access DB data|#]
here is the cde from my implementation:
public List<lightingspecreimp.Lampent> allLightingpro(){
List<Lampent> results=emp.createNamedQuery("getAlldetails").getResultList();
return results;
}
apprecaite your everything. thanks
eve
> From: gordon.yorke_at_oracle.com
> To: persistence_at_glassfish.dev.java.net
> Date: Mon, 3 Dec 2007 16:32:03 -0500
> Subject: RE: question on entity relationships
>
> Hello eve,
> Did you cut and paste that query or type it in? There is a typo in the FROM clause.
>
> @NamedQuery(name ="getAlldetails", query=" SELECT l.pnumb, l.catergory, l.lwoltage, lm.manuname FROM Lampent l LEFT OUTER JOIN *l*.LamManufacturerent lm")
>
> --Gordon
>
> -----Original Message-----
> From: Eve Pokua [mailto:gorgeous65_at_msn.com]
> Sent: Monday, December 03, 2007 4:28 PM
> To: persistence_at_glassfish.dev.java.net
> Subject: RE: question on entity relationships
>
>
>
>
> Thanking you for your reply.
>
> James,
>
> LamManufacturerents is the foreign key in Lampent. LamManufacturerents exists in Lampent. So the query should be like this:
>
>
> @NamedQuery(name ="getAlldetails", query=" SELECT l.pnumb, l.catergory, l.lwoltage, lm.manuname FROM Lampent l LEFT OUTER JOIN lm.LamManufacturerent lm")
>
> But i get the following errors:
>
> [#|2007-12-03T21:18:31.671+0000|INFO|sun-appserver9.1|oracle.toplink.essentials.session.file:/C:/Sun/SDK/domains/domain1/applications/j2ee-apps/LIGHTINGSPEC/LIGHTINGSPEC-ejb_jar/-LIGHTINGSPEC-ejbPU3|_ThreadID=34;_ThreadName=Thread-185;|file:/C:/Sun/SDK/domains/domain1/applications/j2ee-apps/LIGHTINGSPEC/LIGHTINGSPEC-ejb_jar/-LIGHTINGSPEC-ejbPU3 logout successful|#]
>
> [#|2007-12-03T21:18:31.687+0000|SEVERE|sun-appserver9.1|javax.enterprise.system.tools.deployment|_ThreadID=34;_ThreadName=Thread-185;_RequestID=3961ec6a-8774-47c5-876a-b986184d7369;|Exception occured in J2EEC Phase
> java.lang.StackOverflowError
> at java.util.HashMap.get(HashMap.java:300)
> at oracle.toplink.essentials.internal.parsing.ParseTreeContext.pathForVariable(ParseTreeContext.java:198)
> at oracle.toplink.essentials.internal.parsing.VariableNode.resolveClass(VariableNode.java:282)
> at oracle.toplink.essentials.internal.parsing.DotNode.resolveClass(DotNode.java:262)
> at oracle.toplink.essentials.internal.parsing.VariableNode.resolveClass(VariableNode.java:287)
> at oracle.toplink.essentials.internal.parsing.DotNode.resolveClass(DotNode.java:262)
> at oracle.toplink.essentials.internal.parsing.VariableNode.resolveClass(VariableNode.java:287)
> at oracle.toplink.essentials.internal.parsing.DotNode.resolveClass(DotNode.java:262)
> at oracle.toplink.essentials.internal.parsing.VariableNode.resolveClass(VariableNode.java:287)
>
>
> .............................
>
>
> it gos on.
>
> Thankings everyone
>
> eve
>
> ----------------------------------------
> > Date: Mon, 3 Dec 2007 07:08:22 -0800
> > From: jamesssss_at_yahoo.com
> > To: persistence_at_glassfish.dev.java.net
> > Subject: RE: question on entity relationships
> >
> >
> > Do you have any LamManufacturerent that have Lampent? This query will filter
> > out the none case, i.e. you will only get back LamManufacturerents that have
> > 1 or more Lampent.
> >
> > You could use an outerjoin if you do not wish to filter the none case.
> >
> > i.e.
> > SELECT l.pnumb, l.catergory, l.lwoltage, lm.manuname FROM LamManufacturerent
> > lm left outer join lm.lampent l
> >
> >
> > Eve Pokua wrote:
> > >
> > >
> > > Hello James/Everyone, I have finally tried your suggestion but I'm
> > > having problems retrieving data. Below are my to related entities with
> > > their relationships: @Entity_at_Table(name="LAMPS") @Named Queries({
> > > @Named Query(name ="getAlldetails", query=" SELECT l.pnumb, l.catergory,
> > > l.lwoltage, lm.manuname FROM LamManufacturerent lm, in(lm.lampent) l")}
> > > public class Lampent implements Serializable{ .........................
> > > @ManyToOne private LamManufacturerent
> > > lamManufacturerent;................... } @Entity_at_Table(name="LAMPMANU")
> > > public class LamManufacturerent implements
> > > Serializable{............................ @OneToMany(mappedBy =
> > > "lamManufacturerent") private List<Lampent> lampent; .............
> > > } Here is the JPQL: @Named Query(name ="getAlldetails", query=" SELECT
> > > l.pnumb, l.catergory, l.lwoltage, lm.manuname FROM LamManufacturerent lm,
> > > in(lm.lampent) l") Did I get it wrong because it is not working and not
> > > retrieving any data. It however works, if I do some thing like this:
> > > "Select l FROM Lampent l" It brings all data plus all the data from the
> > > related entity LamManufacturerent. But i only want manuname from
> > > LamManufacturerent. Im probably making just a little mistake. Please,
> > > help. Thankseve ________________________________> From:
> > > gorgeous65_at_msn.com> To: persistence_at_glassfish.dev.java.net> Date: Wed, 14
> > > Nov 2007 15:07:03 +0000> Subject: RE: question on entity relationships> >
> > > Thanks James> > I will try it and let you know.> > eve> >> Date: Wed, 14
> > > Nov 2007 06:20:25 -0800>> From: jamesssss_at_yahoo.com>> To:
> > > persistence_at_glassfish.dev.java.net>> Subject: Re: question on entity
> > > relationships>>>>>> The JPQL would be,>>>> "Select i.id, i.name,
> > > i.description, i.colour, i.size, o.oid, o.date,>> o.quantity from Order o,
> > > in(o.items) i">>>> You could also just select the Order and fetch join the
> > > items, if you wanted>> the objects back. Or just select the Orders can
> > > access the items from them>> in Java.>>>> "Select o from Order o join
> > > fetch o.items">>>> "Select o from Order o">>>>>> Eve Pokua wrote:>>>>>>>>>
> > > Hello everyone,>>>>>> I would like to know how to retrieve certain data
> > > from the DB with respect>>> to entity relationship. Consider the following
> > > SQL statement.>>>>>> "Select i.id, i.name, i.description, i.colour,
> > > i.size, o.oid, o.date,>>> o.quantity from Item i, Order o">>>>>> Or a very
> > > complex SQL statement using JOIN in tables.>>>>>> The Order entity is a 1
> > > to many relation to Item - an order can have many>>> items. But when
> > > retrieving the details from order, I want to see certain>>> data from the
> > > Order table as stated above, but not all the data from>>> Order. How do I
> > > achieve this in EJB3 query?>>>>>> Thanks>>>>>> eve>>>>>>>>> ----->> --->>
> > > http://wiki.eclipse.org/User:James.sutherland.oracle.com James
> > > Sutherland>> http://www.oracle.com/technology/products/ias/toplink/ Oracle
> > > TopLink ,>> http://www.eclipse.org/eclipselink/>> EclipseLink ,
> > > https://glassfish.dev.java.net/javaee5/persistence/ TopLink>> Essentials>>
> > > Wiki: http://en.wikibooks.org/wiki/Java_Persistence Java Persistence ,>>
> > > http://wiki.eclipse.org/EclipseLink EclipseLink>> Forums:
> > > http://forums.oracle.com/forums/forum.jspa?forumID=48 TopLink ,>>
> > > http://www.nabble.com/EclipseLink-f26430.html EclipseLink ,>>
> > > http://www.nabble.com/java.net---glassfish-persistence-f13455.html
> > > Glassfish>> Persistence>> -->> View this message in context:
> > > http://www.nabble.com/question-on-entity-relationships-tf4804935.html#a13747259>>
> > > Sent from the java.net - glassfish persistence mailing list archive at
> > > Nabble.com.> > ________________________________> Get free emoticon packs
> > > and customisation from Windows Live. Pimp My
> > > Live!<http://www.pimpmylive.co.uk>
> > > _________________________________________________________________
> > > Get free emoticon packs and customisation from Windows Live.
> > > http://www.pimpmylive.co.uk
> > >
> >
> >
> > -----
> > ---
> > http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland
> > http://www.oracle.com/technology/products/ias/toplink/ Oracle TopLink ,
> > http://www.eclipse.org/eclipselink/
> > EclipseLink , https://glassfish.dev.java.net/javaee5/persistence/ TopLink
> > Essentials
> > Wiki: http://en.wikibooks.org/wiki/Java_Persistence Java Persistence ,
> > http://wiki.eclipse.org/EclipseLink EclipseLink
> > Forums: http://forums.oracle.com/forums/forum.jspa?forumID=48 TopLink ,
> > http://www.nabble.com/EclipseLink-f26430.html EclipseLink ,
> > http://www.nabble.com/java.net---glassfish-persistence-f13455.html Glassfish
> > Persistence
> > --
> > View this message in context: http://www.nabble.com/RE%3A-question-on-entity-relationships-tf4930046.html#a14131601
> > Sent from the java.net - glassfish persistence mailing list archive at Nabble.com.
>
> _________________________________________________________________
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Craig RussellArchitect, Sun Java Enterprise System
http://java.sun.com/products/jdo408 276-5638 mailto:Craig.Russell@sun.comP.S. A good JDO? O, Gasp!
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