diff options
Diffstat (limited to 'lib/sqlalchemy/sql/expression.py')
| -rw-r--r-- | lib/sqlalchemy/sql/expression.py | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py index 0dae6716d..83897ef05 100644 --- a/lib/sqlalchemy/sql/expression.py +++ b/lib/sqlalchemy/sql/expression.py @@ -3170,10 +3170,19 @@ class CompoundSelect(_SelectBaseMixin, FromClause): def _populate_column_collection(self): for cols in zip(*[s.c for s in self.selects]): - proxy = cols[0]._make_proxy(self, name=self.use_labels and cols[0]._label or None) + # this is a slightly hacky thing - the union exports a column that + # resembles just that of the *first* selectable. to get at a "composite" column, + # particularly foreign keys, you have to dig through the proxies collection + # which we generate below. We may want to improve upon this, + # such as perhaps _make_proxy can accept a list of other columns that + # are "shared" - schema.column can then copy all the ForeignKeys in. + # this would allow the union() to have all those fks too. + proxy = cols[0]._make_proxy( + self, name=self.use_labels and cols[0]._label or None) - # place a 'weight' annotation corresponding to how low in the list of select()s - # the column occurs, so that the corresponding_column() operation + # hand-construct the "proxies" collection to include all derived columns + # place a 'weight' annotation corresponding to how low in the list of + # select()s the column occurs, so that the corresponding_column() operation # can resolve conflicts proxy.proxies = [c._annotate({'weight':i + 1}) for i, c in enumerate(cols)] |