GroupedSelection: Rows are refetched after emptyResultSet call [Closes #15]

[hranicka]

This is EXPERIMENTAL hotfix for very annoying Issue #15.

I can't reproduce the bug. It occurs only sometimes after app deploy & cache clean.

Maybe the problem is that Selection::emptyResultSet unsets $rows property.
It's OK because Selection::execute is called before work with the property and when is not set it will be created and it will be an array.

But in some places there are iterations over it and it reproduces an error.
(On another places there is foreach ((array) $this->rows ...) and I can't understand Nette\Database so deeply to make more changes in the code.)

I didn't understand why the error is thrown (see #15).
Now I've tried do anything else. In GroupedSelection the method ::execute is overriden.
But it doesn't write $rows property itself. Now I see it calls parent::execute but it's not called when some cache key is set.

So I think it can be the problem here with GroupedSelection.

1. Selection::emptyResultSet sets $this->rows = NULL.
2. GroupedSelection::execute doesn't call parent::execute and $rows property is null even after it has been called.
3. Now we are in invalid state on some places ($rows property is NULL but we use it in foreach cycles or array access).

What do you think about it?
I muset wait few days or weeks if error will be away or not but as I've said - I can't reproduce the bug intentionally 😢

[hranicka]

Mmm, it's not the right way... I'm completely wrong.

[hranicka]

Sorry. I was trying write test case on the original code but really, I can't reproduce the bug neither after several hours.

It looks like a problem with corrupted cache, invalid cached state or I don't know.
I'm closing this PR which isn't the solution (and generates more SQLs).

[hrach]

If you have the corrupted cache file, try to upload it somewhere and attach to the issue.