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Diffstat (limited to 'docs/howto/custom-model-fields.txt')
| -rw-r--r-- | docs/howto/custom-model-fields.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/docs/howto/custom-model-fields.txt b/docs/howto/custom-model-fields.txt index daaede8e15..fcbda032b7 100644 --- a/docs/howto/custom-model-fields.txt +++ b/docs/howto/custom-model-fields.txt @@ -482,6 +482,16 @@ For example:: return ''.join([''.join(l) for l in (value.north, value.east, value.south, value.west)]) +.. warning:: + + If your custom field uses the ``CHAR``, ``VARCHAR`` or ``TEXT`` + types for MySQL, you must make sure that :meth:`.get_prep_value` + always returns a string type. MySQL performs flexible and unexpected + matching when a query is performed on these types and the provided + value is an integer, which can cause queries to include unexpected + objects in their results. This problem cannot occur if you always + return a string type from :meth:`.get_prep_value`. + Converting query values to database values ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |