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Diffstat (limited to 'lib/sqlalchemy/ext/orderinglist.py')
| -rw-r--r-- | lib/sqlalchemy/ext/orderinglist.py | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/sqlalchemy/ext/orderinglist.py b/lib/sqlalchemy/ext/orderinglist.py index ce63b88ea..ba505eb7b 100644 --- a/lib/sqlalchemy/ext/orderinglist.py +++ b/lib/sqlalchemy/ext/orderinglist.py @@ -73,7 +73,9 @@ Use the ``ordering_list`` function to set up the ``collection_class`` on relatio (as in the mapper example above). This implementation depends on the list starting in the proper order, so be SURE to put an order_by on your relationship. -.. warning:: ``ordering_list`` only provides limited functionality when a primary +.. warning:: + + ``ordering_list`` only provides limited functionality when a primary key column or unique column is the target of the sort. Since changing the order of entries often means that two rows must trade values, this is not possible when the value is constrained by a primary key or unique constraint, since one of the rows |