Hi Walter, > The OpenJPA documentation is very spare about it We are sorry to hear that FetchPlan documentation did not give you a good picture of their capability. It is unfortunate because it is a powerful feature of our runtime.
> Do you have a detailed example? We have a large number of tests in this area but I am afraid that we do not do a good job in explaining it via accessible examples. If you have access to OpenJPA source code then look for Test*Fetch*.java and you will see lots of complex tests. > There is no way to dynamically create a new FetchPlan at runtime? No. There is. EntityManager em = ...; FetchPlan plan = OpenJPAPersistence.cast(em).pushFetchPlan(); > I have to declare FetchGroup by annotations first in order to use the > FetchPlan feature? You can declare named groups in annotations. But you can as well create them programmatically at runtime. Once you create a new one at runtime, then the API methods listed in the manual, helps you to customize which fields you want to access in that plan. > what exactly do I get? My entity with the two fields only? My entity with > two fields filled and the remains initialized to default values? You get your entity with two fields loaded. The other fields are *not* loaded. If you access those other fields within a transaction, OpenJPA will go and fetch them from database. If you access them in a remte process, then they will normally return default values, but you can prohibit access to any unloaded fields via configuration. > Are they initialized with "null" if they are not defined in my custom > FetchGroup? See above. http://openjpa.apache.org/builds/apache-openjpa-1.2.3-SNAPSHOT/docs/javadoc/org/apache/openjpa/persistence/OpenJPAEntityManager.html#pushFetchPlan() [1] http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_fetch ----- Pinaki Poddar Chair, Apache OpenJPA Project -- View this message in context: http://openjpa.208410.n2.nabble.com/Best-practice-Using-fetch-groups-or-a-simple-DTO-tp6598057p6603239.html Sent from the OpenJPA Users mailing list archive at Nabble.com.
