On 13/01/10 6:53 PM, Andrus Adamchik wrote:
Essentially the pipe symbol can only be used with 'matchAllExp'. This is
a special case, and I am not sure it makes sense in a general case.
General case is handled a bit differently via "path aliases". I.e. for
each group of paths that you want to be executed as a single join, you
create a single alias. Different aliases over matching paths generate
separate joins.
Would it make sense to incorporate this idea into the new typesafe Expression
syntax planned for 3.1? That is, you might combine expressions with:
exp1.and(exp2, Expression.SPLIT_PATH)
exp1.and(exp2, Expression.MERGE_PATH)
exp1.and(exp2)
The last would equivalent to Expression.SPLIT_PATH since I'd argue that gives
you the most intuitively meaningful results if the path is joined to-many.
How do you use the aliases approach? The docs are a bit light in that area.
Expression e1 = ExpressionFactory.like("paintings.gallery.name", "foo");
Expression e2 = ExpressionFactory.like("paintings.gallery.name", "bar");
Expression e = e1.andExp(e2);
q = new SelectQuery(Artist.class, e);
q.aliasPathSplits("paintings.gallery","paintings.gallery");
In this example, can the alias and the path have the same name (this means we
don't need to change all the expressions)? In any case, for us this is going to
be complicated because the expressions are created in one place long way away
(in code) from where the SelectQuery is created. So we might have to subclass
Expression in order to carry the extra information about aliases.
Ari
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Aristedes Maniatis
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