Now looking to add splits to SelectQueries, I am wondering if the
approach we discussed before is too "special case". To reiterate, the
idea of a "join split" (CAY-802), was to allow users to override the
default behavior of Cayenne which is to reuse all joins. Here is some
in-depth discussion of useful split scenarios:
http://objectstyle.org/cayenne/lists/cayenne-devel/2003/09/0096.html
I am wading through archives trying to find the pipe ("|") semantics
that Giulio Cesare used for the splits, but IIRC it was something like
this:
rel1.rel2|rel3.rel4
That's fine except that it is targeting a special case of matching a
single path against a collection of values. A more generic case would
be multiple overlapping but different expression paths. E.g.:
rel1.rel2.rel3.rel4
rel1.rel2.rel3.rel5
Split semantics, while rather concise and clear for its intended use,
doesn't help us in dealing with multiple overlapping paths... So how
do we handle those? One possible solution is to follow EJBQL idea and
define aliases for join paths. This way each alias for the same path
generates a separate chain of joins that can be reused if needed. E.g.:
SelectQuery query = ...
query.addQualifierAlias("rel1.rel2", "a");
query.addQualifierAlias("rel1.rel2", "b");
Then the following can be used as qualifier:
a.x
a.rel4
b.y
b.rel5
Any thoughts on that? Would that be better than the pipe sign? (and
did we discuss that before, and I am simply missing it)
Andrus
