Re: auto escaping "NULL"

Il giorno gio, 03/12/2009 alle 18.24 -0500, Jacob Joseph ha scritto:
> Hi.
> Upon trying to insert NULL values into a double precision field, I
> receive the error:
> 
> DataError: invalid input syntax for type double precision: "NULL"
> LINE 4:         (2, -1, E'NULL', 1.11,
> 
> I'm using a statement like:
> curs.execute("INSERT INTO foo (distance) VALUES (%(dist)s)", {'dist':
> None})

That's the correct way and should work. The code you show us is not the
code you're actually executing? ;)

> As a related question, what is the correct way to use the execute(s,
> args) syntax, but *not* escape a particular variable?  Not so
> infrequently, I'd like to use an argument to add an SQL command, such
> as adding to a WHERE or specifying a field.

You should use the normal % operator to build a query string and then
pass it to execute. If you really want to avoid quoting of a bound
variable you can import psycopg2.extras and then wrap the variable in
AsIs() (AsIs just call wrapped object's str() method):

curs.execute("INSERT INTO foo (distance) VALUES (%(dist)s)",
             {'dist': AsIs("NULL")})

But note that this example is a bad use case bacause psycopg knows how
to parse None and you should use AsIs only in very special cases (and
then be ashamed of it.)

federico

-- 
Federico Di Gregorio                         http://people.initd.org/fog
Debian GNU/Linux Developer                                [email protected]
INIT.D Developer                                           fog-NGVKUo/i/[email protected]
 Questo autista me l'ha fatta a cotone!
                                     -- sedicenne palermitana in autobus

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