Hi,
I would guess that one could use null byte to denote "empty field" in
Oracle for example. (I recall seeing such a convention in one of our
non-django apps). And that's to overcome limitation that Oracle doesn't
have real concept of empty string so we stored single null byte to mark
that.
On 15.05.2017 18:54, Tim Graham wrote:
Does anyone know of a use case for using null bytes in
CharField/TextField?
psycopg2 2.7+ raises ValueError("A string literal cannot contain NUL
(0x00) characters.") when trying to save null bytes [0] and this
exception is unhandled in Django which allow malicious form
submissions to crash [1]. With psycopg2 < 2.7, there is no exception
and null bytes are silently truncated by PostgreSQL. Other databases
that I tested (SQLite, MySQL, Oracle) allow saving null bytes. This
creates possible cross-database compatibility problems when moving
data from those databases to PostgreSQL, e.g.[2].
I propose to have CharField and TextField strip null bytes from the
value either a) only on PostgreSQL or b) on all databases. Please
indicate your preference or suggest another solution.
[0] https://github.com/psycopg/psycopg2/issues/420
[1] https://code.djangoproject.com/ticket/28201 - Saving a
Char/TextField with psycopg2 2.7+ raises ValueError: A string literal
cannot contain NUL (0x00) characters is unhandled
[2] https://code.djangoproject.com/ticket/28117 - loaddata raises
ValueError with psycopg2 backend when data contains null bytes
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