diff options
Diffstat (limited to 'lib/sqlalchemy/schema.py')
| -rw-r--r-- | lib/sqlalchemy/schema.py | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/lib/sqlalchemy/schema.py b/lib/sqlalchemy/schema.py index 1dacad3de..212fdac82 100644 --- a/lib/sqlalchemy/schema.py +++ b/lib/sqlalchemy/schema.py @@ -507,6 +507,7 @@ class Column(SchemaItem, expression._ColumnClause): if getattr(self, 'table', None) is not None: raise exceptions.ArgumentError("this Column already has a table!") if not self._is_oid: + self._pre_existing_column = table._columns.get(self.key) table._columns.add(self) if self.primary_key: table.primary_key.add(self) @@ -674,7 +675,14 @@ class ForeignKey(SchemaItem): def _set_parent(self, column): self.parent = column - + + if self.parent._pre_existing_column is not None: + # remove existing FK which matches us + for fk in self.parent._pre_existing_column.foreign_keys: + if fk._colspec == self._colspec: + self.parent.table.foreign_keys.remove(fk) + self.parent.table.constraints.remove(fk.constraint) + if self.constraint is None and isinstance(self.parent.table, Table): self.constraint = ForeignKeyConstraint([],[], use_alter=self.use_alter, name=self.name, onupdate=self.onupdate, ondelete=self.ondelete) self.parent.table.append_constraint(self.constraint) |