form of a some expressions when referring to the ``.c`` collection on a ``select()`` construct, but the ``str()`` form isn't available since the element relies on dialect-specific compilation constructs, notably the ``__getitem__()`` operator as used with a Postgresql ``ARRAY`` element. The fix also adds a new exception class :class:`.UnsupportedCompilationError` which is raised in those cases where a compiler is asked to compile something it doesn't know how to. Also in 0.8.3. [ticket:2780]
- add support for correlations to propagate all the way in; because correlations require context now, need to make sure a select enclosure of any level takes effect any number of levels deep. - fix what we said correlate_except() was supposed to do when we first released #2668 - "the FROM clause is left intact if the correlated SELECT is not used in the context of an enclosing SELECT..." - it was not considering the "existing_froms" collection at all, and prohibited additional FROMs from being placed in an any() or has(). - add test for multilevel any() - lots of docs, including glossary entries as we really need to define "WHERE clause", "columns clause" etc. so that we can explain correlation better - based on the insight that a SELECT can correlate anything that ultimately came from an enclosing SELECT that links to this one via WHERE/columns/HAVING/ORDER BY, have the compiler keep track of the FROM lists that correspond in this way, link it to the asfrom flag, so that we send to _get_display_froms() the exact list of candidate FROMs to correlate. no longer need any asfrom logic in the Select() itself - preserve 0.8.1's behavior for correlation when no correlate options are given, not to mention 0.7 and prior's behavior of not propagating implicit correlation more than one level.. this is to reduce surprises/hard-to-debug situations when a user isn't trying to correlate anything.
target :class:`.Column` has been reworked to be as immediate as possible, based on the moment that the target :class:`.Column` is associated with the same :class:`.MetaData` as this :class:`.ForeignKey`, rather than waiting for the first time a join is constructed, or similar. This along with other improvements allows earlier detection of some foreign key configuration issues. Also included here is a rework of the type-propagation system, so that it should be reliable now to set the type as ``None`` on any :class:`.Column` that refers to another via :class:`.ForeignKey` - the type will be copied from the target column as soon as that other column is associated, and now works for composite foreign keys as well. [ticket:1765]
- docs docs docs
Conflicts: test/profiles.txt test/sql/test_selectable.py
foreign key paths to a table "B", to that table "B", would fail to produce the "ambiguous join condition" error that would be reported if you join table "A" directly to "B"; it would instead produce a join condition with multiple criteria. [ticket:2738]