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gh-92780: Improve sqlite3.Connection.create_collation docs
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erlend-aasland committed May 13, 2022
commit b0a5cf43a00000ac9c604fede0dddce1d7f6a53d
19 changes: 7 additions & 12 deletions Doc/library/sqlite3.rst
Original file line number Diff line number Diff line change
Expand Up @@ -518,22 +518,17 @@ Connection Objects

.. method:: create_collation(name, callable)

Creates a collation with the specified *name* and *callable*. The callable will
be passed two string arguments. It should return -1 if the first is ordered
lower than the second, 0 if they are ordered equal and 1 if the first is ordered
higher than the second. Note that this controls sorting (ORDER BY in SQL) so
your comparisons don't affect other SQL operations.
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erlend-aasland marked this conversation as resolved.
Create a collation named *name* using the collating function *callable*.
*callable* is passed two :class:`string <str>` arguments,
and it should return 1 if the first is ordered higher than the second,
-1 if the first is ordered lower than the second,
and 0 if they are ordered equal.
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erlend-aasland marked this conversation as resolved.
Outdated

Note that the callable will get its parameters as Python bytestrings, which will
normally be encoded in UTF-8.

The following example shows a custom collation that sorts "the wrong way":
The following example shows a reverse sorting collation:

.. literalinclude:: ../includes/sqlite3/collation_reverse.py

To remove a collation, call ``create_collation`` with ``None`` as callable::

con.create_collation("reverse", None)
Remove a collation function by setting *callable* to :const:`None`.

.. versionchanged:: 3.11
The collation name can contain any Unicode character. Earlier, only
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