Re: [SQLObject] Why does converters.py/stringLikeConverter escape linebreaks and others

[Oleg B. <ph...@ph...>]

[CC to the mailing list]

On Wed, Jun 05, 2013 at 09:57:01AM +0200, de...@af... wrote:
> 
> Hi Oleg,
> 
> thanks for your fast reply. It pointed me to the solution. postgres
> 9.1 on ubtuntu server 12.04 has standard_conforming_strings enabled
> by default.
> Turning it off solved my problem.
> 
> Thomas

   Turning standard_conforming_strings off is not required since
SQLObject 1.2: http://sqlobject.org/News.html#sqlobject-1-2-0

"Support for PostgreSQL 7.* is dropped. The minimal supported version
of PostgreSQL is 8.1 now.

Quoting rules changed for PostgreSQL: SQLObject uses E'' escape string
if the string contains characters escaped with backslash."

> Am 05.06.2013 09:15, schrieb Oleg Broytman:
> >On Wed, Jun 05, 2013 at 08:54:20AM +0200, Thomas Siemion <de...@af...> wrote:
> >>Hey folks,
> >>
> >>I was wondering why the sqlrepr from converters.py is escaping
> >>linebreaks and other chars for postgres.
> >>
> >>I'm talking about this piece of code:
> >>
> >>sqlStringReplace = [
> >>      ("'", "''"),
> >>      ('\\', '\\\\'),
> >>      ('\000', '\\0'),
> >>      ('\b', '\\b'),
> >>      ('\n', '\\n'),
> >>      ('\r', '\\r'),
> >>     ('\t', '\\t'),
> >>]
> >>
> >>This causes for e.g. \ to multiply. when I comment out everything but
> >>the escaping of the single quote everything works as aspected. I don't
> >>see the reason why this is done in the first place.
> >>
> >>Could anyone please explain this to me and why this is done when saving
> >    See
> >http://www.postgresql.org/docs/8.4/static/sql-syntax-lexical.html#SQL-SYNTAX-CONSTANTS
> >
> >    "PostgreSQL also accepts "escape" string constants, which are an
> >extension to the SQL standard. An escape string constant is specified by
> >writing the letter E (upper or lower case) just before the opening
> >single quote, e.g., E'foo'. (When continuing an escape string constant
> >across lines, write E only before the first opening quote.) Within an
> >escape string, a backslash character (\) begins a C-like backslash
> >escape sequence, in which the combination of backslash and following
> >character(s) represent a special byte value, as shown in Table 4-1."
> >
> >    Also see https://dev.mysql.com/doc/refman/5.0/en/string-literals.html
> >
> >>but not undone when loaing?
> >    Because there is no need to "undone" anything. The backend doesn't
> >store escaped values -- it stores normal values that it sends back on
> >SELECTing.
> >
> >>Regards
> >>Thomas
> >Oleg.
> 

Oleg.
-- 
     Oleg Broytman            http://phdru.name/            ph...@ph...
           Programmers don't die, they just GOSUB without RETURN.