Obviously I mean Entity kind as the first point. On Nov 2, 3:12 pm, "l.denardo" <[email protected]> wrote: > Generally speaking, what Didier says is entirely true. > > Mappings are, for my experience, done as follows > *Entity name is the class name without package extension > *Properties names are field names > *Property kind is mapped according to this > pagehttp://code.google.com/appengine/docs/java/datastore/dataclasses.html... > > If you want to investigate how your entities are mapped you can use > the Local Testing > utilitieshttp://code.google.com/appengine/docs/java/tools/localunittesting.html > > Just do something like this in a test class: > > *Persist the object using JDO > *Obtain the datastore service mock thru the testing tools > *Query the datastore for the kind you just created, then you can > iterate on entity property. > > The main disadvantage in guessing the mapping is that you lose type > checks: all entities kinds are of one of the core value types, so > you'll need to explicitly convert it from/to your POJO field types. > This is closely related to what Didier emphasizes. > > So I too advise you to investigate it as a testing practice, but do > not rely on it in production. > Regards > > Lorenzo > > On Nov 2, 10:26 am, Didier Durand <[email protected]> wrote: > > > Hi George, > > What you are looking for is anyway possible: the JDO/JPA entities are > > stored in datastore as Entities eventually. You'll have to figure out > > (i.e reverse engineer) the mapping between the pojo annotations and > > the corresponding ds structures. > > > I see 1 big issue: the mapping that you will figure out has no > > guarantee from Google, it can change any time and you may need some > > time to figure out when it changes with risks for the integrity of > > your data. > > > I would either work at high or low level on a given piece of data but > > not simultaneously if you can't have "guarantees". > > > regards > > didier > > > On Nov 2, 8:58 am, George Moschovitis <[email protected]> > > wrote: > > > > I know about Objectify but I would like to use a standard solution > > > like JPA/JDO. > > > Even if it is (currently) less efficient than custom solutions. > > > > -g. > > > > On Nov 1, 12:32 pm, Didier Durand <[email protected]> wrote: > > > > > Hi George, > > > > > Not a direct answer to your question, but if you're looking for > > > > something "lighter" than JDO/JPA, I would encourage you to have a look > > > > at Objectify: it's much closer to DS api than JPA/JDO (and much > > > > simpler and more efficient...) but still provides a good level of > > > > abstraction for efficient programming. > > > > > Something that could be tried (as Objectify uses some JPA annotation) > > > > is to remap JPA entities onto Objectify entities but it very much > > > > depends on your level of sophistication in the use of JPA. > > > > > regards > > > > > didier > > > > > On Oct 31, 10:08 pm, George Moschovitis > > > > > <[email protected]> wrote: > > > > > Is there a way to convert a JDO/JPA POJO to the corresponding > > > > > Datastore Entity? I am sure this functionality exists in the JDO/JPA > > > > > implementation but is this exposed in a public API? (maybe through a > > > > > helper). > > > > > > This would allow mixing calls to JDO/JPA with calls to the low-level > > > > > API for special case optimizations. > > > > > > regards, > > > > > George.
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