Hi again, > You are using the term runtime. To me that means that I have > to go in and > physically change my class-descriptor in the repository.xml. > before my app > starts up. Then when the one query has been used I go change the > repository.xml back for all the others and start the app > again. I am NOW > assuming that you mean that you can change the class-descriptor > programatically from within the app for a particular query > and then restore > it back to it's normal state. Is this accurate?
exactly ! > Where is this > in the docs > and how do you do it? http://jakarta.apache.org/ojb/apidocs/org/apache/ojb/broker/PersistenceBroke r.html#getDescriptorRepository() http://jakarta.apache.org/ojb/apidocs/org/apache/ojb/broker/PersistenceBroke r.html#getClassDescriptor(java.lang.Class) http://jakarta.apache.org/ojb/apidocs/org/apache/ojb/broker/PersistenceBroke r.html#setClassDescriptor(org.apache.ojb.broker.metadata.ClassDescriptor) http://jakarta.apache.org/ojb/apidocs/org/apache/ojb/broker/metadata/ClassDe scriptor.html I also posted a code sample that shows how to do this some time ago to the list. please search the mail archive. > > I read an email that followed yours and it seemed to be > thinking your were > suggesting the same thing :-) > > Terminology is a bizarre creature. Communication is a matter of luck :-) cheers, Thomas > Cheers, > Brandon Goodin > Phase Web and Multimedia > P (406) 862-2245 > F (406) 862-0354 > [EMAIL PROTECTED] > http://www.phase.ws > > > -----Original Message----- > > From: Mahler Thomas [mailto:[EMAIL PROTECTED]] > > Sent: Monday, September 02, 2002 9:20 AM > > To: 'OJB Users List' > > Subject: AW: SELECT statements and OJB > > > > > > Hi > > > > > > > > I am thick headed... please forgive me. But one last > > > question. (see question > > > below). > > > > > > > -----Original Message----- > > > > From: Mahler Thomas [mailto:[EMAIL PROTECTED]] > > > > Sent: Monday, September 02, 2002 8:24 AM > > > > To: 'OJB Users List' > > > > Subject: AW: SELECT statements and OJB > > > > > > > > > > > > Hi again, > > > > > > > > > > 1. OJB does *not* perform "select * from", for queries! > > > > > > If you look up objects of class x OJB will read the > > > > > class-descriptor for > > > > > > class x and determine all necessary columns to materialize > > > > > an x instance. > > > > > > The performed select contains all those columns. > > > > > > > > > > > > If you want to limit the number of columns you can > modify the > > > > > > class-descriptor for class X do get a reduced > number of columns. > > > > > > > > > > > > > > > > So, if i needed a full person to be materialized in one place > > > > > and only the > > > > > id, firstname and lastname elsewhere then I would have to > > > > > write a couple of > > > > > classes and their associated class-descriptor. For example my > > > > > PersonName and > > > > > Person would be two different object classes that are > > > > > populated from the > > > > > same table (PEOPLE). > > > > > > > > NO! You only need one persistent class Person. > > > > You can modify the existing class-descriptor for class > > > Person at runtime. > > > > that is for one query you remove all columns you don not > > > want to see from > > > > the classdescriptor. > > > > After finishing the query you restore the class-descriptor > > > to its original > > > > Form so that all other things work normally. > > > > > > I guess what i am saying here is i need both representations > > > in the same > > > web-app. For example, within the same web application, i have > > > a place where > > > you can 1) select a person to edit and 2) a place to edit > a person's > > > information. > > > > > > 1) This requires that i retrieve only the ID, FIRSTNAME AND > > > LASTNAME of all > > > the records in the PEOPLE database. I then display the names > > > on an html > > > page. The user then selects which person they want to edit > > > and we are off to > > > edit that person's info. In this case i only want to > populate the id, > > > firstName and lastName variables in the Person object/class > > > and store it > > > into a collection to be traversed on the html page and > > > displayed. My problem > > > arises in reusing my Person class because i already have it > > > in use with step > > > 2's class descriptor. If i undestand you correctly i will > > > have to create a > > > BasicPerson class that only contains the id, firstName > and lastName > > > variables and a class descriptor that maps to the BasicPerson > > > class. > > > > As stated in my original mail: > > NO! You only need one persistent class Person!!! > > You can modify the existing class-descriptor for class > Person at runtime. > > that is for one query you remove all columns you don not > want to see from > > the classdescriptor. > > After finishing the query you restore the class-descriptor > to its original > > Form so that all other things work normally. > > > > > Please > > > read on to step 2) > > > > > > 2) This requires that i retrieve all of the fields for a > > > particular person > > > from the database table PEOPLE and populate a Person object > > > to pass to the > > > form that will be populated by that information for editing. > > > Therefore, i > > > would set up my class descriptor to get all the column > values from the > > > database and poulate the Person class which has the > accordingly mapped > > > setters and getters. At the same time in the same app i have > > > need for just > > > the retrieval of the PEOPLE table's ID,FIRSTNAME and > > > LASTNAME. In this case > > > i am listing all of the names of the people so that a name > > > can be selected > > > to edit a person's info. I don't want to get all the other > > > fields in the > > > records because it would be pointless to populate it with all > > > the colums > > > from the PEOPLE table cuz i don't need them. > > > > > > Conclusion: > > > > > > Now, does this mean that i would have to have two different > > > classes mapped > > > with two different class-descriptors to handle each of these > > > situations. > > > > NO !!! > > (Could somebody else please tro to explain this? I have no > idea why you > > still believe that you will need two classes?) > > > > > > > > If yes, then are there any planned enhancements to allow for > > > more efficient > > > reuse of classes? > > > > > > > > I am afraid that you might take my questioning as an insult. > > > > Not as an insult. I simply do not get what you do not > understand in my > > reply? > > > > cheers, > > Thomas > > > > > I don't mean it > > > that way. I just want a clear and accurate picture of what i > > > am able to and > > > not able to do. Also, you documentation and work on this is > > > execellent. I > > > know that projects grow faster than their docs and that's > > > just reality. > > > Great Work! I never meant to say otherwise. > > > > > > > > > > > > > > > -- > > > To unsubscribe, e-mail: > > > <mailto:[EMAIL PROTECTED]> > > > For additional commands, e-mail: > > > <mailto:[EMAIL PROTECTED]> > > > > > > > -- > > To unsubscribe, e-mail: > <mailto:[EMAIL PROTECTED]> > > For additional commands, e-mail: > <mailto:[EMAIL PROTECTED]> > > > > > > > -- > To unsubscribe, e-mail: > <mailto:[EMAIL PROTECTED]> > For additional commands, e-mail: > <mailto:[EMAIL PROTECTED]> > -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
