Re: Problem with raw query and using in

On Sat, 16 Nov 2013 22:39:09 +0100, Thorsten Sanders
<thorsten.sanders@gmx.net> declaimed the following:

>I am using mysql and when I write it like (1) then I get int is not
>iterable on the first one, but the raw works, if I do it like (1,) the
>first one works, but the raw one gets again the comma at the end, tried
>several ways always one of both not working, for me it looks kinda there
>is some magic happening and with only 1 value the comma is not removed,
>but is removed with several values.
>
>For now I just use 2 variables one for the raw queries and one for the
>other, not the best solution, but works for now.
>
>
>Am 16.11.2013 16:01, schrieb Javier Guerra Giraldez:
>> On Sat, Nov 16, 2013 at 7:40 AM, Thorsten Sanders
>> <thorsten.sanders@gmx.net> wrote:
>>> realms=[1]
>>> data = AuctionData.objects.filter(itemid__exact=itemid,realm__in=realms)
>>> data2 = AuctionData.objects.raw('SELECT * FROM auctiondata_auctiondata WHERE
>>> itemid_id=%s AND realm_id in %s ',[itemid,realms])
>>
>> not sure if it's related. but most SQL adaptors use a tuple for the
>> IN(...) parameters, not a list.
>>
>> check http://initd.org/psycopg/docs/usage.html#tuples-adaptation
>>

I suspect the main problem is that you need to set up the realms
parameter differently -- along with the query string.

MySQL, and most other SQL systems, as I recall, expect to see

... needle in (first, second, ..., last)

MySQLdb sanitizes parameters by converting them to a string
representation, escaping any special characters, and wrapping it is '
marks.

In the raw query, unless Django has an SQL parser, the above is
generating

select * from auctiondata_auctiondata where itemid_id = 'something' and
realm_id in '[1]'

when what you need to generate is

select * from auctiondata_auctiondata where itemid_id = 'something' and
realm_id in ('1')

(MySQLdb doesn't know what datatype to put in at each %s -- it has first
converted all inputs into safe strings; that's why it uses %s for the
placeholder).

If using a list of values, you'll have to create an SQL format with a
%s for EACH value, not the list

SQL = " ...%%s and stuff in (%s)" % ", ".join("%s" for x in realms)
(if realms is [1, 3, 99] this creates
SQL ="... %s stuff in (%s, %s, %s" )

You then need to flatten the parameters

parms=[itemid].extend(realms)

--
Wulfraed Dennis Lee Bieber AF6VN
wlfraed@ix.netcom.com HTTP://wlfraed.home.netcom.com/

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