Re: How to create cayenne datamap on the fly

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Sat Jul 07 2007 - 14:07:07 EDT

  • Next message: mr.abanjo: "Re: How to create cayenne datamap on the fly"

    Hi there,

    Actually Cayenne is one of the few ORM engines where you can define
    both your metadata, and persistent objects on the fly if you want to.
    So...

    1. While I never tried loading DataMap XML from a remote URL, it
    should work. Just subclass
    'org.objectstyle.cayenne.conf.DefaultConfiguration', overriding
    'getMapConfiguration' method to open a remote URL. You may find this
    page useful when doing that:

    http://cayenne.apache.org/doc20/customizing-configuration.html

    2. Yes, you can totally do that using generic persistent classes:

    http://cayenne.apache.org/doc20/generic-persistent-class.html

    The main trick is to access the objects via DataObject interface
    methods instead of concrete setters and getters.

    Andrus

    On Jul 7, 2007, at 1:12 AM, mr.abanjo wrote:

    > Hi all,
    > i'm writing an application that try to be indipendent from the
    > business
    > logic required.
    > The main idea behind this project is to use reflection to create on
    > the fly
    > the bean (CayenneDataObject) that normally i must write for map the
    > databese
    > structure.
    > What i need is:
    > 1) load cayenne data map xml from a URL. Basically this URL point to a
    > servlet that generate it on the fly. Normally this is the
    > configuration in
    > cayenne.xml:
    >
    > <map name="datamap-foo" location="META-INF/cayenne-datamap-
    > foo.map.xml" />
    >
    > whant i need is something like this:
    >
    > <map name="datamap-foo" location="
    > http://somedomain/cayenne-datamap-foo.map.xml" />
    >
    > is it possible?
    >
    > 2) i need to generate some DataObject on the fly. So i'm thinking
    > to use
    > Reflection. Do you think that is possible? The main idea is that
    > at runtime
    > i don't know the structure of my entity. For example, "user" can be
    > composed
    > only by "name" and "surname" attribute... or... have also
    > "address".. and so
    > on. I don't want to create every time the corresponding DataObject.
    > I want
    > to implements an engine that create them on demand.
    >
    > I don't know if this is a right approch on the problem. Maybe
    > cayenne has
    > some API for doing this type of activity.
    >
    > Thanks in advance, for help.
    >
    > D.

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