Re: OT? plpython2u

2016-10-20 13:06 GMT-05:00 Jonathan Rogers <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?​

>
> >
> > 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?
> highlight=Image#PIL.Image.fromstring
>
> 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
>
> --
> Jonathan Rogers
> Socialserve.com by Emphasys Software
> jrogers(at)emphasys-software(dot)com
>
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*Nahum Castro González*
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