Description

attach_to_table has been included for UniqueConstraint and Index to allow users to choose whether to include or withhold them from the Table (Table.constraints for UniqueConstraint, Table.indexes for Index). attach_to_table defaults to True for both UniqueConstraint and Index. So if set to True or not included UniqueConstraint / Index will be added to the Table.

For UniqueConstraint, setting attach_to_table to False prevents parent.constraints.add(self) from executing in Column._set_parent(). attach_to_table is checked via getattr
For Index, setting attach_to_table to False prevents table.indexes.add(self) from executing in Index._set_parent()

force_attach has been included in Table.append_constraints(), and carried via **kw , to allow users to override attach_to_table. For situations where UniqueConstraint or Index was defined before the Table creation and attach_to_table is set to False, users can use that same UniqueConstraint or Index to append to table at a later time. For example unique_constraint = UniqueConstraint("x", attach_to_table=False) or index = Index("x", attach_to_table=False), then Table is defined, then Table.append_constraint(unique_constraint) or Table.append_constraint(index).

For UniqueConstraint, regardless of attach_to_table, using Table.append_constraint(constriant) allows for execution of parent.constraints.add(self) in Column._set_parent().
For Index, regardless of attach_to_table, using Table.append_constraint(index) allows for execution of table.indexes.add(self) in Index._set_parent().

Fixes: #13048

Checklist

This pull request is:

• A documentation / typographical / small typing error fix
  • Good to go, no issue or tests are needed
• A short code fix
  • please include the issue number, and create an issue if none exists, which
    must include a complete example of the issue. one line code fixes without an
    issue and demonstration will not be accepted.
  • Please include: Fixes: #<issue number> in the commit message
  • please include tests. one line code fixes without tests will not be accepted.
• A new feature implementation
  • please include the issue number, and create an issue if none exists, which must
    include a complete example of how the feature would look.
  • Please include: Fixes: #<issue number> in the commit message
  • please include tests.

Have a nice day!