OJB Books In The Works?
I see that there's a Hibernate book from Manning in review: http://www.theserverside.com/resources/HibernateReview.jsp Are there any OJB books in the works? I know I'd like to see one. I've been away from this list for a while, so please excuse me if the topic has already been thrashed within an inch of its life. Thanks - MOD __ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: regression test errors
I should have thought of that - thanks. MOD --- Mahler Thomas <[EMAIL PROTECTED]> wrote: > Here is some food for thought: > http://db.apache.org/ojb/links.html > > ;-) > Thomas > > > -Original Message- > > From: Michael Duffy [mailto:[EMAIL PROTECTED] > > Sent: Tuesday, April 01, 2003 6:30 PM > > To: OJB Users List; [EMAIL PROTECTED] > > Subject: Re: regression test errors > > > > > > > > Thank you, Thomas, I think I'll take your advice > and > > stick with PB API. For some reason, I thought you > > intended it as a lower layer API, with ODMG to be > > preferred. > > > > Later in this thread both you and Bonnie referred > to > > "all the usual suspects" for O/R mapping papers. > I've > > got copies of Scott Ambler's papers and one by > > Wolfgang Keller that is quite good. I've yet to > score > > a copy of Fowler's architecture patterns book. > What > > else would you recommend that someone read? What > are > > the papers "everyone knows" in this area? Thanks > in > > advance for the education. - MOD > > > > > > --- Thomas Mahler <[EMAIL PROTECTED]> wrote: > > > Hi again Michael, > > > > > > Michael Duffy wrote: > > > > Thanks to both Thomas and Armin for their > replies > > > on > > > > this thread. > > > > > > > > Speaking for myself, I'm nervous about using > OJB > > > on my > > > > current project, too, but I don't think the > source > > > is > > > > entirely OJB. A big part of it is fear of > what I > > > > DON'T know. I very much liked the idea of > using a > > > > tool, developed by folks more expert than me. > I > > > know > > > > enought about JDBC to be able to do CRUD > > > operations > > > > and simple transactions, but the idea of > having a > > > > layer to abstract all that out of business > objects > > > was > > > > appealing. > > > > > > > > I heard Martin Fowler talk a few months ago. > He > > > > mentioned using JAXOR as an O/R mapping tool. > > > When I > > > > looked into it, I found NO documentation > > > whatsoever. > > > > > > > > Google quickly turned up OJB as an > alternative. I > > > > liked it right away, because it had more > > > documentation > > > > than JAXOR, it the cachet of being a Jakarta > > > project, > > > > and the stuff that I did actually worked. Now > > > I've > > > > got a tree of four tables linked with m:n > > > > associations, all working in JUnit tests. > > > > > > > > All that's well and good, but now I'm nervous > > > about > > > > that learning curve and what I'm ignorant of. > > > I've > > > > done everything with the PersistenceBroker API > > > because > > > > it was easy to follow in the docs. But now > I'm > > > > thinking that I should really be doing all of > this > > > > using ODMG API instead. More learning, with a > > > > deadline approaching. > > > > > > choosing the actual OJB API is an important > > > decision. > > > > > > Why do you think you should use ODMG ? Do you > really > > > need Object level > > > transactions? > > > > > > If you plan to build your own persistence > Manager > > > layer with Data Access > > > Objects (DAO) (and possibly DTOs) you could be > > > better of with the PB API. > > > > > > The PB API gives you maximum flexibility and > nicely > > > fits into J2EE based > > > programming models. > > > > > > The ODMG API specification was designed as a > > > two-tier rich client API. > > > > > > > > > > > > > > Here's a fundamental question: > > > > > > > > RDBMS developers have put a lot of effort into > > > > maintaining referential integrity, managing > > > > transactions, etc. It seems to me that OJB is > > > taking > > > > over a lot of that stuff. When I created my > > > tables, I > > > > didn't add foreign key constraints. I left > all > > > that > > > > to OJB. The ODMG API will
Re: regression test errors
Thank you, Thomas, I think I'll take your advice and stick with PB API. For some reason, I thought you intended it as a lower layer API, with ODMG to be preferred. Later in this thread both you and Bonnie referred to "all the usual suspects" for O/R mapping papers. I've got copies of Scott Ambler's papers and one by Wolfgang Keller that is quite good. I've yet to score a copy of Fowler's architecture patterns book. What else would you recommend that someone read? What are the papers "everyone knows" in this area? Thanks in advance for the education. - MOD --- Thomas Mahler <[EMAIL PROTECTED]> wrote: > Hi again Michael, > > Michael Duffy wrote: > > Thanks to both Thomas and Armin for their replies > on > > this thread. > > > > Speaking for myself, I'm nervous about using OJB > on my > > current project, too, but I don't think the source > is > > entirely OJB. A big part of it is fear of what I > > DON'T know. I very much liked the idea of using a > > tool, developed by folks more expert than me. I > know > > enought about JDBC to be able to do CRUD > operations > > and simple transactions, but the idea of having a > > layer to abstract all that out of business objects > was > > appealing. > > > > I heard Martin Fowler talk a few months ago. He > > mentioned using JAXOR as an O/R mapping tool. > When I > > looked into it, I found NO documentation > whatsoever. > > > > Google quickly turned up OJB as an alternative. I > > liked it right away, because it had more > documentation > > than JAXOR, it the cachet of being a Jakarta > project, > > and the stuff that I did actually worked. Now > I've > > got a tree of four tables linked with m:n > > associations, all working in JUnit tests. > > > > All that's well and good, but now I'm nervous > about > > that learning curve and what I'm ignorant of. > I've > > done everything with the PersistenceBroker API > because > > it was easy to follow in the docs. But now I'm > > thinking that I should really be doing all of this > > using ODMG API instead. More learning, with a > > deadline approaching. > > choosing the actual OJB API is an important > decision. > > Why do you think you should use ODMG ? Do you really > need Object level > transactions? > > If you plan to build your own persistence Manager > layer with Data Access > Objects (DAO) (and possibly DTOs) you could be > better of with the PB API. > > The PB API gives you maximum flexibility and nicely > fits into J2EE based > programming models. > > The ODMG API specification was designed as a > two-tier rich client API. > > > > > > Here's a fundamental question: > > > > RDBMS developers have put a lot of effort into > > maintaining referential integrity, managing > > transactions, etc. It seems to me that OJB is > taking > > over a lot of that stuff. When I created my > tables, I > > didn't add foreign key constraints. I left all > that > > to OJB. The ODMG API will handle true > transactions > > and object/row locking. > > The OJB/ODMG does have pessimistic object level > locking. But it does not > provide DB row level locking! > > > > > But what if OJB isn't the only path into the > database? > > A DBA might balk at leaving all those things that > the > > RDBMS would handle to OJB. Is it possible still > leave > > foreign key constraints in the database so others > > could use them without OJB? > > Yes! It's generally a good idea to let the DB > maintain data integrity as > much as possible. OJB was designed to work smoothly > with existing databases. > The ODMG transaction manager also takes care not to > conflict with > database foreign key constraints. > > If you want to sync OJB and non-OJB apps working > against the same db you > have to take care of at least two issues: > 1. Autoincremented Sequence Numbers. The Default OJB > SequenceManager is > not aware of external processes. So you have to use > a SequenceManager > implementation that uses database managed sequence > numbers (or > Identies). There are several such implementations in > the sequenceManager > package. > > 2. All processes working against the db should use > optimistic locking to > avoid data disintegrity. OJB supports OL based on > Version and timestamp > columns. > > > > > My compliments to Thomas, Armin, and the team that > >
Re: regression test errors
Thanks to both Thomas and Armin for their replies on this thread. Speaking for myself, I'm nervous about using OJB on my current project, too, but I don't think the source is entirely OJB. A big part of it is fear of what I DON'T know. I very much liked the idea of using a tool, developed by folks more expert than me. I know enought about JDBC to be able to do CRUD operations and simple transactions, but the idea of having a layer to abstract all that out of business objects was appealing. I heard Martin Fowler talk a few months ago. He mentioned using JAXOR as an O/R mapping tool. When I looked into it, I found NO documentation whatsoever. Google quickly turned up OJB as an alternative. I liked it right away, because it had more documentation than JAXOR, it the cachet of being a Jakarta project, and the stuff that I did actually worked. Now I've got a tree of four tables linked with m:n associations, all working in JUnit tests. All that's well and good, but now I'm nervous about that learning curve and what I'm ignorant of. I've done everything with the PersistenceBroker API because it was easy to follow in the docs. But now I'm thinking that I should really be doing all of this using ODMG API instead. More learning, with a deadline approaching. Here's a fundamental question: RDBMS developers have put a lot of effort into maintaining referential integrity, managing transactions, etc. It seems to me that OJB is taking over a lot of that stuff. When I created my tables, I didn't add foreign key constraints. I left all that to OJB. The ODMG API will handle true transactions and object/row locking. But what if OJB isn't the only path into the database? A DBA might balk at leaving all those things that the RDBMS would handle to OJB. Is it possible still leave foreign key constraints in the database so others could use them without OJB? My compliments to Thomas, Armin, and the team that created OJB. None of this fear is a reflection on your excellent work. It has more to do with the fact that this is still a version 1.0 release candidate and my own ignorance. Sincerely, MOD --- Thomas Mahler <[EMAIL PROTECTED]> wrote: > Hi Bonnie, > > Bonnie MacKellar wrote: > > I was not at Mobius before 1999, so I really would > not know... > > > > Yes, this is for an important project and I am not > feeling > > very good about this. The alternatives though, are > to buy > > something or do it ourselves. Our company tends to > be of > > the "do it yourself" mentality. Since what we > need is exactly > > what OJB provides, it seems silly to replicate it. > > On the other hand, it is often easier to deal with > bugs > > in your own code then with bugs in someone else's > code. > > OJB is 3 years of heavy designed code by experts in > the O/R area. > We have a complete regression testsuite that covers > each and every > aspect of the system. > > Do it yourself is definitely a bad idea in this > area. If you don't trust > us better use a commercial tool like TopLink. > > OJB is in production use in large projects for 2 > years now. > My company is using OJB in several large and mission > critical software > projects since a year now. > > > > > I would feel a lot better about this if the mail > archives > > worked. My usual approach with this kind of system > is > > to really sift through user archives, looking for > similar > > experiences. > > I admit this is really annoying. But this is clearly > not an OJB problem, > but an infrastructure problem with some Apache > server. > For the time being use archive mirrors at GMANE or > at > http://www.mail-archive.com/ojb-user%40db.apache.org/ > > cheers, > Thomas > > > > > Bonnie > > > > -Original Message- > > From: Michael Duffy [mailto:[EMAIL PROTECTED] > > Sent: Friday, March 28, 2003 1:19 PM > > To: OJB Users List > > Subject: RE: regression test errors > > > > > > > > Bonnie, > > > > I'm responding to a note you sent to the OJB > mailing > > list. > > > > Is Mobius based in the NYC area? I knew a guy > named > > Howard Deiner who worked at a company named > Mobius. > > His tenure would have been prior to 1999. Just > > curious. > > > > Also curious - will the system you'll be > installing > > OJB into be a large production application? I've > been > > getting OJB up and running for a smaller > production > > project, and I'm nervous about it. I see all the > > problems on the mailing list and sketchy > documentation &g
RE: regression test errors
Bonnie, I'm responding to a note you sent to the OJB mailing list. Is Mobius based in the NYC area? I knew a guy named Howard Deiner who worked at a company named Mobius. His tenure would have been prior to 1999. Just curious. Also curious - will the system you'll be installing OJB into be a large production application? I've been getting OJB up and running for a smaller production project, and I'm nervous about it. I see all the problems on the mailing list and sketchy documentation and wonder what I'm getting myself into. JMHO, of course. Are you feeling the same way? Thanks - MOD --- Bonnie MacKellar <[EMAIL PROTECTED]> wrote: > > Thanks for the advice. > This parameter is set in > C:\db-ojb-1.0.rc1\target\test\ojb\repository_database.xml, > right? Do I need to change anything else to modify > this behavior? > > I'm still trying to feel my way around this system. > Basically, I have > about a week to make a recommendation on using it, > in a large project. > Ease of use is an important consideration, > especially to the powers-that-be > who are managing this project. > > Bonnie > > -Original Message- > From: Armin Waibel > [mailto:[EMAIL PROTECTED] > Sent: Wednesday, March 26, 2003 6:42 PM > To: OJB Users List > Subject: Re: regression test errors > > Seems a problem with the used sequence manager > (SequenceManagerHighLowImpl). > Try to run the test cases with > SequenceManagerInMemoryImpl > Do you get the same results? > > __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: How to use Criteria.addEqualByColumn
Jakob, I'm a bozo. It was operator error (again). The m:n stuff is working fine in both directions. I apologize for bothering you. Sincerely, MOD --- Jakob Braeuchi <[EMAIL PROTECTED]> wrote: > hi michael, > > ojb handles non-decomposed m:n relationships > internally. there's no need > for you to deal with the intermediate table. > > jakob > > Michael Duffy wrote: > > >I have an m:n relationship between two > tables/classes > >A and B, modeled with an A_TO_B intermediate table > >in-between. > > > >I'd like to get all the instances of B associated > with > >a given A as a Collection. The SQL might look > like: > > > >SELECT * FROM B > >WHERE > >B.B_ID = A_TO_B.B_ID AND > >A_TO_B.A_ID = X; > > > >where X is the value of the A.A_ID that I want. > > > >Is Criteria.addEqualToColumn the right method, or > >should I just toss in raw SQL using SQLCriteria? > How > >do I get back the Collection if I use raw SQL? Any > >advice is most welcome. > > > >Also, the list is broken on the db.apache.org Web > >site. Notes younger than 24Feb2003 don't appear. > >Thanks - MOD > > > > > >__ > >Do you Yahoo!? > >Yahoo! Platinum - Watch CBS' NCAA March Madness, > live on your desktop! > >http://platinum.yahoo.com > > > >- > >To unsubscribe, e-mail: > [EMAIL PROTECTED] > >For additional commands, e-mail: > [EMAIL PROTECTED] > > > > > > > > > > > - > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: How to use Criteria.addEqualByColumn
Hi, Jakob! I've been having some trouble navigating this. (I suspect it's newbie problems.) I have m:n relationships working fine with a single pair of objects, but when I try to turn them on between four sets of objects I get exceptions in my JUnit tests. They're all working in one direction (from top to bottom: A->B->C->D), but not bi-directionally. Another question: I hae a foreign key relationship between two classes where I want to pull two column values out of a table and populate member data in a class. I only see one table attribute in the . When I want to point to foreign key using , it's almost as if I HAVE to map the value I want to a class with its own table. The repository.xml docs say that the table attribute on may specify a table different from the mapped table for the persistent class, but it's currently not implemented. Do I really have to wrap a java.util.Date in a separate class in this case, or is there another way to do it? Thanks - MOD --- Jakob Braeuchi <[EMAIL PROTECTED]> wrote: > hi michael, > > ojb handles non-decomposed m:n relationships > internally. there's no need > for you to deal with the intermediate table. > > jakob > > Michael Duffy wrote: > > >I have an m:n relationship between two > tables/classes > >A and B, modeled with an A_TO_B intermediate table > >in-between. > > > >I'd like to get all the instances of B associated > with > >a given A as a Collection. The SQL might look > like: > > > >SELECT * FROM B > >WHERE > >B.B_ID = A_TO_B.B_ID AND > >A_TO_B.A_ID = X; > > > >where X is the value of the A.A_ID that I want. > > > >Is Criteria.addEqualToColumn the right method, or > >should I just toss in raw SQL using SQLCriteria? > How > >do I get back the Collection if I use raw SQL? Any > >advice is most welcome. > > > >Also, the list is broken on the db.apache.org Web > >site. Notes younger than 24Feb2003 don't appear. > >Thanks - MOD > > > > > >__ > >Do you Yahoo!? > >Yahoo! Platinum - Watch CBS' NCAA March Madness, > live on your desktop! > >http://platinum.yahoo.com > > > >- > >To unsubscribe, e-mail: > [EMAIL PROTECTED] > >For additional commands, e-mail: > [EMAIL PROTECTED] > > > > > > > > > > > - > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
m:n Chaining
I've worked through the Person/Project m:n example and gotten everything working. The real problem that I'm trying to model is a four-level tree: four tables (A, B, C, D) with m:n relationships between each. I've been unsuccessful at getting all the relationships working. I've managed to get them from the top down (A->B->C->D), but not from the bottom up. Has anyone else tried something like this? Thanks-MOD __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
How to use Criteria.addEqualByColumn
I have an m:n relationship between two tables/classes A and B, modeled with an A_TO_B intermediate table in-between. I'd like to get all the instances of B associated with a given A as a Collection. The SQL might look like: SELECT * FROM B WHERE B.B_ID = A_TO_B.B_ID AND A_TO_B.A_ID = X; where X is the value of the A.A_ID that I want. Is Criteria.addEqualToColumn the right method, or should I just toss in raw SQL using SQLCriteria? How do I get back the Collection if I use raw SQL? Any advice is most welcome. Also, the list is broken on the db.apache.org Web site. Notes younger than 24Feb2003 don't appear. Thanks - MOD __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
m:n Question
I've got an m:n association that's causing me a problem. Let's say I have two Java classes, A and B, that have underlying database tables and an m:n association between them. Both A and B have members of type java.util.Collection that maintain references to the other. I have a constructor for A that allows me to create an empty collection of B references. When I test creating and storing an instance of class A with an empty collection of B references OJB throws a java.util.NoSuchElementException: "Thrown by the nextElement method of an Enumeration to indicate that there are no more elements in the enumeration." Does OJB not allow me to persist an instance of class A which has no references to class B, or have I made another newbie mistake? Thank you. - MOD __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Query against Collection with more than one addEqualTo statement.
The empty collection result makes perfect sense if the
default behavior is to AND criteria together. None of
your articles have both names set (exclusion at work),
so nothing comes back.
Aren't you trying to say "Give me all the articles
where name = 'Article 1' OR name = 'Article 2'"?
If I understand correctly, I think you want to use
either the addOrCriteria or addIn methods. - MOD
--- Gregor Heinze <[EMAIL PROTECTED]> wrote:
> For the sake of simplicity, I refer to the class
> model from the tutorial
> "Advanced Object Relational Mapping techniques" to
> explain my problem. It
> seems to be quite simple but I wasn't able to figure
> it out correctly.
> All I want to do is to get all ProductGroup's which
> have an Article with the
> articleName "Article 1" _and_ an Article with the
> articleName "Article 2" in
> its allArticlesInGroup Vector.
> Using the PersistenceBroker API I wrote the
> following:
>
> Criteria crit = new Criteria();
> crit.addEqualTo("allArticlesInGroup.articleName",
> "Article 1");
> crit.addEqualTo("allArticlesInGroup.articleName",
> "Article 2");
> Query q = QueryFactory.newQuery(ProductGroup.class,
> crit);
>
> Unfortunately this approach does not work and I
> always get an empty result
> collection. Using only one addEqualTo statement
> works as expected but using
> two of them won't.
> Anyone has an idea how to do this? Any help is
> appreciated!
>
> Thanks in advanced,
> Gregor
>
>
>
-
> To unsubscribe, e-mail:
> [EMAIL PROTECTED]
> For additional commands, e-mail:
> [EMAIL PROTECTED]
>
__
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Re: Adding A New Component With A 1:1 Relationship
Thomas, Of course you're correct. I'd added foreign key constraints to all my tables. Once I removed them, OJB did the INSERT and managed all the keys for me, as you said. I apologize for missing that subtlety. Should I also remove foreign key constraints on many-to-many tables? I've got three of them in this schema. Will OJB handle those as nicely as the 1:1? "...I agree, there is a learning curve with OJB. O/R mapping is not trivial. But it is worth the effort. Once you mastered the learning curve you will ask yourself, how could I write database applications without an O/R tool?..." - I totally agree with this statement. That's why I'm persisting with OJB, even if it makes me nervous about my release date. IMHO, two great benefits of an object/relational mapping layer are that they force SQL code out of the business objects and they allow CMP without entity EJBs. You can write J2EE without an app server; J2EE and EJB need not be synonymous. Thank you again for your fine work and timely advice. Sincerely, MOD --- Thomas Mahler <[EMAIL PROTECTED]> wrote: > Hi Michael, > > Michael Duffy wrote: > > I have a newbie question, if you don't mind. > > > > Your advanced O/R tutorial shows a 1:1 mapping > example > > with Article and ProductGroup classes. You've > shown > > the table schemas (in German, but I follow you) > and > > the repository_user.xml. All very good, of > course. > > > > The repository XML for Article has a > productGroupId > > that points to the ProductGroup key, and an > instance > > of ProductGroup that is supposed to be owned by > the > > Article. > > > > Now if I want to ask the broker to store a brand > new > > Article, how do I do it? Is the productGroupId > > required to be set to an existing before I call > > broker.store(newArticle)? > > Depends on the database. If there is a FK constraint > then yes. > But as you can see from the table schema, there are > no formal FK > constraints. So, the productGroupId needs not to be > filled. > > > If I want to have a new > > ProductGroup for my Article, do I have to do this > as a > > five-step transaction? > > > > 1. Create a new ProductGroup instance > > 2. Store the new ProductGroup instance > > 3. Get the latest ProductGroup instances's primary > key > > 4. Create a new Article, using the PG primary key > > 5. Store the new Article > > No it's much easier, as OJB takes care of FK > assigment automatically: > 1. Create a new Article a > 2. Create a new ProductGroup instance pg > 3. call a.setProductGroup(pg) > 4. store the new Article. > > OJB manages the FK assignment for you. If you have > set > auto-update="true" on the productGroup > reference-descriptor then OJB > will also store the new PG on storing the new > article! > > > > I'm sure it's my lack of understanding, because > this > > feels very difficult. I'm still climbing that OJB > > learning curve. > > I agree, there is a learning curve with OJB. O/R > mapping is not trivial. > But it is worth the effort. Once you mastered the > learning curve you > will ask yourself, how could I write database > applications without an > O/R tool? > > cheers, > Thomas > > > > > Thank you for your work, help, and patience. > > Sincerely, MOD > > > > > > __ > > Do you Yahoo!? > > Yahoo! Platinum - Watch CBS' NCAA March Madness, > live on your desktop! > > http://platinum.yahoo.com > > > > > - > > To unsubscribe, e-mail: > [EMAIL PROTECTED] > > For additional commands, e-mail: > [EMAIL PROTECTED] > > > > > > > > - > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Adding A New Component With A 1:1 Relationship
I have a newbie question, if you don't mind. Your advanced O/R tutorial shows a 1:1 mapping example with Article and ProductGroup classes. You've shown the table schemas (in German, but I follow you) and the repository_user.xml. All very good, of course. The repository XML for Article has a productGroupId that points to the ProductGroup key, and an instance of ProductGroup that is supposed to be owned by the Article. Now if I want to ask the broker to store a brand new Article, how do I do it? Is the productGroupId required to be set to an existing before I call broker.store(newArticle)? If I want to have a new ProductGroup for my Article, do I have to do this as a five-step transaction? 1. Create a new ProductGroup instance 2. Store the new ProductGroup instance 3. Get the latest ProductGroup instances's primary key 4. Create a new Article, using the PG primary key 5. Store the new Article I'm sure it's my lack of understanding, because this feels very difficult. I'm still climbing that OJB learning curve. Thank you for your work, help, and patience. Sincerely, MOD __ Do you Yahoo!? Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! http://platinum.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: how to obtain the SQL code from a Query object?
I don't have javadocs for the
org.apache.ojb.broker.accesslayer.sql package. Have I
gotten mine from the wrong place? Thanks - MOD
--- Mahler Thomas <[EMAIL PROTECTED]> wrote:
> Mhh,
>
> I don't know all API changes since 0.9.5 by heart,
> but the
> SqlGeneratorFactory is really a very old piece of
> code.
> have a look in the
> org.apache.ojb.broker.accesslayer.sql package
>
> Maybe you can also instaiate SqlGenerator directly?!
>
> cheers,
> Thomas
>
> > -Original Message-
> > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]
> > Sent: Monday, March 17, 2003 4:30 PM
> > To: [EMAIL PROTECTED]
> > Subject: RE: how to obtain the SQL code from a
> Query object?
> >
> >
> > Thomas,
> >
> > Thanks for your help!
> >
> > How do you use this SqlGeneratorFactory. This
> class doesn't
> > seem to be in OJB 0.9.5.
> >
> > I think that I could migrate to 1.0 but I don't
> know what
> > exactly I will have to change in my code.
> >
> > Best.
> > Sylvain
> >
> > -Message d'origine-
> > De: Mahler Thomas
> [mailto:[EMAIL PROTECTED]
> > Date: lundi, 17. mars 2003 16:12
> > À: 'OJB Users List'
> > Objet: RE: how to obtain the SQL code from a Query
> object?
> >
> >
> > Hi Sylvain,
> >
> > I think so!
> > But you can use the SqlGeneratorFactory to obtain
> a
> > SqlGenerator instance
> > instead!
> >
> > cheers,
> > Thomas
> >
> > > -Original Message-
> > > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]
> > > Sent: Monday, March 17, 2003 3:59 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: RE: how to obtain the SQL code from a
> Query object?
> > >
> > >
> > > Hi Thomas,
> > >
> > > I can't find the broker.serviceSqlGenerator()
> method.
> > >
> > > I'm using OJB 0.9.5.
> > > Is it the problem?
> > >
> > > Thanks
> > > Sylvain
> > >
> > >
> > >
> > > -Message d'origine-
> > > De: Mahler Thomas
> [mailto:[EMAIL PROTECTED]
> > > Date: lundi, 17. mars 2003 10:59
> > > À: 'OJB Users List'
> > > Objet: RE: how to obtain the SQL code from a
> Query object?
> > >
> > >
> > > The Query object is not able to return SQL code,
> as it does
> > > not have any
> > > platform specific know how.
> > > You have to ask the OJB SqlGenerator component
> to generate SQL:
> > >
> > > PersistenceBroker broker = ...
> > > Query query = ...;
> > > ClassDescriptor cld = ...;
> > >
> > > // obtain prepared stmt sql:
> > > String sql =
> > >
>
broker.serviceSqlGenerator().getPreparedSelectStatement(query,
> > > cld);
> > >
> > > // obtain no prepared sql:
> > > sql =
> >
>
broker.serviceSqlGenerator().getSelectStatementDep(query,
> cld);
> > >
> > > cheers,
> > > thomas
> > >
> > > > -Original Message-
> > > > From: [EMAIL PROTECTED]
> > > [mailto:[EMAIL PROTECTED]
> > > > Sent: Monday, March 17, 2003 10:32 AM
> > > > To: [EMAIL PROTECTED]
> > > > Subject: how to obtain the SQL code from a
> Query object?
> > > >
> > > >
> > > > Hello,
> > > >
> > > > I have this query:
> > > >
> > > > code
> > > > Criteria crit = new Criteria();
> > > > crit.addEqualTo("workstationName", "U68111");
> > > >
> > > > Query query = new
> QueryByCriteria(Workstation.class, crit, true);
> > > > code
> > > >
> > > > Is there a way to obtain the SQL query (select
> * from
> > > > Workstation where) from the query object?
> > > >
> > > > Thanks
> > > > Sylvain
> > > >
> > > >
> > >
> >
>
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> > >
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ojb v0.9.9 problem
I, too, experienced the same problem that Jemmee Yung and Ferran Parra did. Jemmee's solution, changing the jcd-alias in repository.xml to read "repository.xml" does indeed work. Thank you, Jemmee, for pushing my efforts forward. But personally I'm not satisfied with this. I'd like to know if the workaround is a bug or a fundamental misunderstanding on my part. I thought the jcd-alias value was supposed to be used for lookups. (That's the way I used it in tutorial1.) Can anybody tell me what the proper idiom is for jdbc-alias? Thanks - MOD __ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
