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| author | Malcolm Tredinnick <malcolm.tredinnick@gmail.com> | 2008-12-16 06:43:18 +0000 |
|---|---|---|
| committer | Malcolm Tredinnick <malcolm.tredinnick@gmail.com> | 2008-12-16 06:43:18 +0000 |
| commit | b58a260c56c5d05d71ac1073bc05eda8eca0ea5f (patch) | |
| tree | e5b97f4febeff7778807893e6025aced59ff7c50 /docs/ref/models | |
| parent | fddc0c589e03c1e5eb581aaa947a39720163d7d5 (diff) | |
Fixed #9431 -- Added extra validation for VARCHAR-based fields on MySQL.
max_length > 255 and unique=True is not permitted. Based on a patch from
adamnelson.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@9650 bcc190cf-cafb-0310-a4f2-bffc1f526a37
Diffstat (limited to 'docs/ref/models')
| -rw-r--r-- | docs/ref/models/fields.txt | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/docs/ref/models/fields.txt b/docs/ref/models/fields.txt index 4f2a92a66b..52508c7e5c 100644 --- a/docs/ref/models/fields.txt +++ b/docs/ref/models/fields.txt @@ -327,6 +327,13 @@ The admin represents this as an ``<input type="text">`` (a single-line input). The maximum length (in characters) of the field. The max_length is enforced at the database level and in Django's validation. +.. note:: + + If you are writing an application that must be portable to multiple + database backends, you should be aware that there are restrictions on + ``max_length`` for some backends. Refer to the :ref:`database backend + notes <ref-databases>` for details. + .. admonition:: MySQL users If you are using this field with MySQLdb 1.2.2 and the ``utf8_bin`` @@ -341,7 +348,8 @@ The admin represents this as an ``<input type="text">`` (a single-line input). .. class:: CommaSeparatedIntegerField(max_length=None, [**options]) A field of integers separated by commas. As in :class:`CharField`, the -:attr:`~CharField.max_length` argument is required. +:attr:`~CharField.max_length` argument is required and the note about database +portability mentioned there should be heeded. ``DateField`` ------------- @@ -654,9 +662,10 @@ Like a :class:`PositiveIntegerField`, but only allows values under a certain containing only letters, numbers, underscores or hyphens. They're generally used in URLs. -Like a CharField, you can specify :attr:`~CharField.max_length`. If -:attr:`~CharField.max_length` is not specified, Django will use a default length -of 50. +Like a CharField, you can specify :attr:`~CharField.max_length` (read the note +about database portability and :attr:`~CharField.max_length` in that section, +too). If :attr:`~CharField.max_length` is not specified, Django will use a +default length of 50. Implies setting :attr:`Field.db_index` to ``True``. |