Hi Corneliu!
I also had doubts about using JDO in GAE when I started to work with it. Especially because I met several bugs and it was annoying and time wasting to figure out what was going wrong. But then the bugs were fixed in the next release, so I think the guys are generally doing a good job. About the limitation with the non-existing property, you are right. It seems to me that JDO will create a property with a null value once you declare and map it. Do you have a real-life scenario where this limitation is an issue that you cannot overcome with the features provided by JDO? I think if you really need to have some entities having some properties, and others not, and still use JDO, then you could try to map different classes to the same database entity, with different properties defined in the classes. I have never tried that though, so I am not sure if it would work, and definitely would not be convenient. About mapping collections with many entities inside, I think I just wouldn't do it. If the collection is too big to be effectively loaded into memory, then you are right to be using queries instead. In this case you should not map it as a collection, but handle the parent- child relationship explicitly. But still, collection mapping can be a convenient option if you have only a small number of entities in your collection. This does not make JDO less flexible, on the contrary, it introduces an extra service. Your idea about processing just part of the results at once in a query seems to be okay. I think a similar approach is described to handle pagination of large result sets somewhere in the forums. As for me, I would not recommend you to create your own data access layer using the low level API unless you really need it or you really do not need any of the features that JDO provides. It still provides some convenient features that you would have to live without or reimplement if you decide not to use JDO (starting with mapping java classes to persistent storage, which I think is a good thing). Most of the problems you mentioned are not solved by using the low level API anyway, so if you want to create some classes that make data access easier for you applications then you can build them on top of JDO as well, without any major drawbacks. And as final reason why to use JDO, these guys who wrote the docs recommended to do so, and they must have some reason to say that. :) Marton --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-java@googlegroups.com To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en -~----------~----~----~----~------~----~------~--~---
