Re: OT? plpython2u

Oh, Awesome.

Thanks a lot.

Nahum.

2016-10-20 14:47 GMT-05:00 Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>:

> On 10/20/2016 12:03 PM, Nahum Castro wrote:
>
>>
>>
>> 2016-10-20 13:06 GMT-05:00 Jonathan Rogers <jrogers(at)socialserve(dot)com
>> <mailto:jrogers(at)socialserve(dot)com>>:
>>
>>
>> On 10/20/2016 01:14 PM, Nahum Castro wrote:
>> > Hello all.
>> >
>> > I need to process images on my database, they are stored on a bytea
>> column.
>> >
>> > The process consist on scaling and I have done this so far:
>> >
>> > CREATE OR REPLACE FUNCTION ajustar(randstring bytea)
>> > RETURNS bytea AS
>> > $$
>> > import PIL
>> > from PIL import Image
>> > basewidth = 300
>> > img = randstring
>> > wpercent = (basewidth/float(img.size[0]))
>> > hsize = int((float(img.size[1])*float(wpercent)))
>> > img = img.resize((basewidth,hsize), PIL.Image.ANTIALIAS)
>> >
>> > return img
>> > $$
>> > LANGUAGE 'plpython2u' VOLATILE;
>>
>> As you probably know, Postgres procedural languages are server-side
>> extensions and therefore have nothing to do with psycopg, which is a
>> client-side library.
>>
>> ​Thanks, but rather than help in plpython is how to pass the variable
>> bytea from postgres to an image in python.
>>
>>
>> >
>> > The objective of this pl is read the bytea from the database, scale,
>> > then replace the scaled image in the database, but I don't know
>> what
>> > type use to pass to the variable img.
>>
>> AFAICT, if you pass a bytea value to a plpythonu function, it will
>> receive a Python str object.
>>
>>
>> ​That is where i get confused, what is stored in the db is in bytea, how
>> I do to transform in a str?​
>>
>
> It is done for you:
>
> https://www.postgresql.org/docs/9.5/static/plpython-data.html#AEN65498
>
> "PostgreSQL bytea is converted to Python str in Python 2 and to bytes in
> Python 3. In Python 2, the string should be treated as a byte sequence
> without any character encoding.
>
> When the PostgreSQL return type is bytea, the return value will be
> converted to a string (Python 2) or bytes (Python 3) using the respective
> Python built-ins, with the result being converted to bytea."
>
>
> So something like this:
>
> CREATE OR REPLACE FUNCTION public.ajustar(randstring bytea)
> RETURNS bytea
> LANGUAGE plpythonu
> AS $function$
> from io import BytesIO
> import PIL
> from PIL import Image
> basewidth = 300
> mem_file = BytesIO()
> mem_file.write(randstring)
> img = Image.open(mem_file)
> wpercent = (basewidth/float(img.size[0]))
> hsize = int((float(img.size[1])*float(wpercent)))
> img = img.resize((basewidth,hsize), PIL.Image.ANTIALIAS)
>
> return img
> $function$
>
>
> postgres(at)test=# select ajustar(barcode) from pict_test where full_upc =
> '744835000544';
> ajustar
> ------------------------------------------------------------
> ----------------------------------------------------------------------
>
> \x3c50494c2e496d6167652e496d61676520696d616765206d6f64653d52
> 47422073697a653d333030783230392061742030783746393343314532333635303e
> (1 row)
>
>
> barcode are small png's in this case.
>
>
>>
>>
>>
>> >
>> > This is the query.
>> > update personal set foto=ajustar(encode(foto, 'hex')::bytea);
>>
>> Why are you encoding the binary data into a textual representation?
>> What
>> image format is stored in column "foto"? Depending on the format, you
>> probably want to use one of these constructors in function "ajustar":
>>
>>
>> ​Sorry I forgot, all images are in jpeg​ format.
>>
>>
>>
>> http://pillow.readthedocs.io/en/3.4.x/reference/Image.html?h
>> ighlight=Image#PIL.Image.fromstring
>> <http://pillow.readthedocs.io/en/3.4.x/reference/Image.html?
>> highlight=Image#PIL.Image.fromstring>
>>
>> http://pillow.readthedocs.io/en/3.4.x/reference/Image.html?h
>> ighlight=Image#PIL.Image.open
>> <http://pillow.readthedocs.io/en/3.4.x/reference/Image.html?
>> highlight=Image#PIL.Image.open>
>>
>>
>> ​Again thanks.​
>> Nahum
>>
>>
>>
>> --
>> Jonathan Rogers
>> Socialserve.com by Emphasys Software
>> jrogers(at)emphasys-software(dot)com <mailto:jrogers(at)emphasys-software(dot)com>
>>
>> --
>> Jonathan Rogers
>> Socialserve.com by Emphasys Software
>> jrogers(at)emphasys-software(dot)com <mailto:jrogers(at)emphasys-software(dot)com>
>>
>>
>> --
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>>
>>
>>
>> --
>> *Nahum Castro González*
>> Blvd. Perdigón 214, Brisas del Lago.
>> CP 37207
>> León, Guanajuato, México
>> Tel (477)1950304
>> Cel (477)1274694
>>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>

--
*Nahum Castro González*
Blvd. Perdigón 214, Brisas del Lago.
CP 37207
León, Guanajuato, México
Tel (477)1950304
Cel (477)1274694