Re: Correct way to use a JPA*QueryVisitor with a filter class that is not a JPA entity

[Sergey Beryozkin]

Hi
On 21/10/13 07:21, Jim Talbut wrote:
Hi,
I have a JPA data model that I'm trying to use with CXF's SearchContext.

In order to constrain the searching that can be done I'm trying to use a
search class that is not a JPA entity (and that just contains a subset
of the JPA fields).
Q1. Is this the right way to solve this problem?
Q2. How should I get it to work?

Details:

I have a "User" interface that the "User_JpaImpl" entity class derives
from.
I also have a "UserFilter" class that just has two properties (username
& enabled) - the User interface also has getters and setters for these
properties, but there is no relationship between UserFilter and User (or
User_JpaImpl).

My best attempt so far looks like this:
         SearchCondition<UserFilter> sc =
searchContext.getCondition(UserFilter.class);
         JPACriteriaQueryVisitor<UserFilter, User_JpaImpl> visitor =
             new JPACriteriaQueryVisitor<>(entityManager,
UserFilter.class, User_JpaImpl.class);
         searchCondition.accept(visitor);

         TypedQuery<User_JpaImpl> query = visitor.getTypedQuery();
         List<? extends User> result = query.getResultList();

This throws an exception in accept because of this:
         if (builder == null) {
             builder = em.getCriteriaBuilder();
             cq = builder.createQuery(queryClass);
             root = cq.from(tClass);
             predStack.push(new ArrayList<Predicate>());
         }

tClass is UserFilter.class, which is not known to JPA and thus cannot be
used as root (cq.from(tClass) throws IllegalArgumentException).


All I want to do is limit the set of fields that can be queried, if this
is the wrong approach I'm happy to swap it for another.


I believe the JPA2 way is to use either JPA2 Tuple or capturing 
beans/arrays which will filter  the 'username' & 'enabled' properties at 
JPA/DB level, the JPA2 section has a couple of examples and 
JPATypedQueryVisitorTest has few more (to do with different styles of 
shaping the output), I'd probably go for using Tuple.

If you prefer to use a custom UserFilter then I guess you'd need to use
JPATypedQueryVisitor<User_JpaImpl> and then filter the result list with 
the filter afterwards

Thanks, Sergey

Thanks.

Jim