QueryBuilder and an empty array in criteria

[urugator]

Passing an empty array as criteria's parameter, for example:

$qb->whereCriteria(array('e.id !=' => array()))

will result in SQL query containing:

WHERE m0_.id NOT IN (?)

and therefore returning an empty result set, which is quite unexpected.

It might be better to add aditional check for array emptiness and completely skip adding WHERE part to the query in case it's empty.

[fprochazka]

Are you sure that skipping the condition is the best solution?
Wouldn't something like NOT IN (NULL) be better?

[urugator]

Not sure if there is any special null handling in Doctrine's DQL, but SQL:
SELECT id WHERE id NOT IN (NULL)
is basically translated to
SELECT id WHERE id <> NULL
which always returns an empty set, because any comparison operation returns NULL if any operand is NULL, and NULL is further considered as FALSE. (AFAIK this behavior is DB specific and can be configured in some cases, so I wouldn't rely on null handling in any case)

[tkraut]

I think that skipping condition is proper solution.
Condition that says that id should not be one from empty set means that id can be arbitrary, but NOT IN (NULL) is opposite, it filters out all results.

[fprochazka]

I see now. I agree that with NOT IN it makes sense, but it doesn't with plain IN.

[urugator]

My apologize, I wasn't clear enough in the description, that negation is indeed crucial.