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[eclipselink-users] Question regarding cb.conjunction() and the resulting Predicate's getExpressions() method
I am going through some legacy code of ours.

We have a WHERE clause being assembled programmatically through the JPA criteria API.

The clause begins life like this:

  Predicate filter = cb.conjunction();

Then, based on various things the user has supplied, this WHERE clause might get added to.  Here's one example:

  filter = cb.and(filter, cb.like(cb.upper(path), paramDescription));

Then there's a block of code that attempts to see if the where clause should be bolted on to the rest of the query.  This part I wrote, and it is never firing, and I think I've gravely misunderstood something.

Here's what I wrote:

  if (!filter.getExpressions().isEmpty()) { // XXX filter.getExpressions() is always empty!
    criteriaQ.where(filter);
  }

This block never "fires" because filter.getExpressions() is always of size 0.  Debugging into the EclipseLink 2.3.2 source (the one that comes with GlassFish 3.1.2.2), I find that at this stage filter is a CompoundExpressionImpl, and that class does this in the body of its getExpressions() method:

  public List<_expression_<Boolean>> getExpressions(){
    return new ArrayList();
  }

However, his (inherited) expressions instance field is of size 2.  Eep. Is this an oversight, or--I suspect--by design and I am just being clueless about how to work with the criteria builder API?  Is there a different way of determining whether I need to invoke the where() method?

Thanks,
Laird

--
http://about.me/lairdnelson

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