New submission from Ingo Ruhnke:
When a sqlite database contains invalid UTF-8 code in a TEXT column, Python can
query that data normally when .text_factory is set appropriately. However when
a custom function is created with .create_function() and applied to that column
the custom function will receive 'None' as argument instead of the value of the
column.
The following example demonstrate the issue:
Example:
--------
import sqlite3
import sys
import os
con = sqlite3.connect(":memory:")
con.text_factory = os.fsdecode
con.create_function("py_identity", 1, lambda x: x)
cur = con.cursor()
cur.execute("CREATE TABLE foo(bar TEXT)")
# insert some invalid UTF-8 into the database
cur.execute("INSERT INTO foo(bar) VALUES(cast(? AS TEXT))", [b"\xff"])
# try to call a custom function on the invalid UTF-8
cur.execute("SELECT "
" typeof(bar), "
" bar, " # this works
" py_identity(bar), " # this returns None instead of the content
of 'bar'
" cast(py_identity(cast(bar as BLOB)) AS TEXT) " # this works
around the issue
"FROM foo")
for row in cur:
print(row)
Output:
-------
('text', '\udcff', None, '\udcff')
Expected:
---------
('text', '\udcff', '\udcff', '\udcff')
----------
components: Library (Lib)
messages: 283674
nosy: Ingo Ruhnke
priority: normal
severity: normal
status: open
title: Custom functions in sqlite receive None on invalid UTF-8
type: behavior
versions: Python 3.6
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue29021>
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