I'm not sure how to do exactly what you're asking, but I have an alternative
suggestion: You could just query everything and do the filter at the
application level (i.e. in Python), rather than in the query.
Because Python is awesome, this is now easy to write:
custom_string = 'foobar'
parcours = self.session.query(Parcours).all()
parcours = [parcour for parcour in parcours if (
custom_string.lower() in parcour.parcours_name.lower()
or
parcour.parcours_name.lower() in custom_string.lower()]
I've done this in a few places in my current application where I needed
string.startswith() logic.
Of course, if you're going to have a lot of data in the table, this might not
be a good idea. Querying the entire table will increase your bandwidth
(although SQLAlchemy's lazy loading will help here), and filtering the list in
Python will probably be slower than letting the database use it. Although, if
there are a lot of clients connecting to the database, moving the filter from
the DB to the clients might help to reduce the load on the database server.
It's hard to say without knowing your situation. If in doubt, try both and
profile.
Cheers,
Cam
-----Original Message-----
From: sqlalchemy@googlegroups.com [mailto:sqlalchemy@googlegroups.com] On
Behalf Of yannack
Sent: Wednesday, 8 February 2012 4:35 AM
To: sqlalchemy
Subject: [sqlalchemy] String matching
Hello list,
I have the following problem. I wish to query my database to look for
columns with names included in, or including, a given string.
is there a way to do the opposite of "contains", ie, a "contained"
method for string columns? Right now, I am doing the following:
session.query(Parcours).filter(
or_(
Parcours.parcours_name.ilike('%'+custom_string+'%'),
literal_column("'"+custom_string
+"'").ilike('%'+Parcours.parcours_name+'%'))
this works "ok" for most stuff, but breaks when custom_strings has
quotes and such. Therefore, I need to improve on this:
- either by escaping the custom_string ?
- or by taking another approach than the "ilike" route (I use ilike
instead of contains simply because I don't know how to do case-
insensitive "contains" in PGSQL and my code will have to run both on
sqlite and PGSQL)
also, is there a case-insensitive version of the "contains" method
(which would generate ilike statements instead of like in postgresql
while properly escaping quotes and other stuff) ?
Finally, I am also open to any thoughts and pointers people may have
concerning partial/approaching string matching. At the moment, I just
do this contains/contained, case-insensitive search, and finish with
some manual matching, but if anyone has opinions on this, I am of
course very interested!
Thanks for your time,
Best regards,
Yannick
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalchemy@googlegroups.com.
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
-------------------------------------------------------------------------
DISCLAIMER: This e-mail transmission and any documents, files and
previous e-mail messages attached to it are private and confidential.
They may contain proprietary or copyright material or information that
is subject to legal professional privilege. They are for the use of
the intended recipient only. Any unauthorised viewing, use, disclosure,
copying, alteration, storage or distribution of, or reliance on, this
message is strictly prohibited. No part may be reproduced, adapted or
transmitted without the written permission of the owner. If you have
received this transmission in error, or are not an authorised recipient,
please immediately notify the sender by return email, delete this
message and all copies from your e-mail system, and destroy any printed
copies. Receipt by anyone other than the intended recipient should not
be deemed a waiver of any privilege or protection. Thales Australia
does not warrant or represent that this e-mail or any documents, files
and previous e-mail messages attached are error or virus free.
-------------------------------------------------------------------------
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalchemy@googlegroups.com.
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
