Work w/ prefetch even for selects, if present

Fixed bug in new CTE feature for update/insert/delete stated
as a CTE inside of an enclosing statement (typically SELECT) whereby
oninsert and onupdate values weren't called upon for the embedded
statement.

This is accomplished by consulting prefetch
for all statements.  The collection is also broken into
separate insert/update collections so that we don't need to
consult toplevel self.isinsert to determine if the prefetch
is for an insert or an update.  What we don't yet test for
are CTE combinations that have both insert/update in one
statement, though these should now work in theory provided
the underlying database supports such a statement.

Change-Id: I3b6a860e22c86743c91c56a7ec751ff706f66f64
Fixes: #3745

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 16ca7f959..095c84f03 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -359,6 +359,8 @@ class SQLCompiler(Compiled):
     True unless using an unordered TextAsFrom.
     """
 
+    insert_prefetch = update_prefetch = ()
+
     def __init__(self, dialect, statement, column_keys=None,
                  inline=False, **kwargs):
         """Construct a new :class:`.SQLCompiler` object.
@@ -428,6 +430,10 @@ class SQLCompiler(Compiled):
         if self.positional and dialect.paramstyle == 'numeric':
             self._apply_numbered_params()
 
+    @property
+    def prefetch(self):
+        return list(self.insert_prefetch + self.update_prefetch)
+
     @util.memoized_instancemethod
     def _init_cte_state(self):
         """Initialize collections related to CTEs only if