On 7/17/2012 2:05 AM, Oliver Gierke wrote:
> Hi all,
>
> there are multiple (contradicting) sections in the spec defining the error cases of EntityManager.createQuery(…). The JavaDoc in 3.1.1 states:
>
>> /**
>> * …
>> * @throws IllegalArgumentException if the query string is
>> * found to be invalid
>> */
>> public Query createQuery(String qlString);
>
> Below the code sample we find the following section:
>
>> If the argument to the createQuery method is not a valid Java Persistence query string or a valid CriteriaQuery object, the IllegalArgumentException may be thrown or the query execution will fail and a PersistenceException will be thrown.
>
> What does "may be thrown" exactly mean? Why is query execution discussed in this context? Does that mean that createQuery(…) might return a Query object that will only fail eventually when being executed?
Yes. The provider may defer this check until the point where the query is to be executed.
If so, why is this allowed actually? If so how can one reliably check a query string for syntactical correctness?
>
> I currently have code that tries to validate a query string by calling em.createQuery(…) and catching IllegalArgumentException as defined in the JavaDoc. Unfortunately I've just discovered Hibernate (3.x and 4.x) throwing IllegalStateException in case the query tree seems valid in general but fails being parsed later on.
>
> em.createQuery("somethingAbsurd") -> IllegalArgumentException
> em.createQuery("select disinct(u) from User u") -> IllegalStateException
>
> I'd like to get a clear picture on what is actually required before filing a ticket against Hibernate. Is it worth to straighten that out in the upcoming version of the spec?
>
This point was discussed back in the JPA 1.0 days when this decision was made.
I'd like to hear the points of view of the JPA implementations represented here as to whether
it would be desirable to strengthen the requirements here or not. For example, we could
consider adding a query property to indicate that the query string should be validated early.
-LInda
> Cheers,
> Ollie
>