Flask-SQLAlchemy not saving database updates

Question

I am trying to import data into existing database items. There are two fields that I want to update for each data base item: a string type field caled imagefolder and a picketype (list) field called images. The input values for both fields are strings that store file paths.

My steps are to query the database item, check for its existance, and then update its fields.

blend = Blend.query.filter_by(old_ID=row[4]).first()
if blend:
    blend.imagefolder = "/".join((row[16].split("/")[4:])[:-1])
    blend.images.append(ntpath.basename(row[16]))
    db.session.commit()

When I run the script nothing happens (the database doesn't update), and I noticed that the import script runs really quickly, too quickly.

Shouldn't it be old_ID==row[4]? (Two equal signs...)

Ian McLaird
– Ian McLaird

2019-04-13 21:34:43 +00:00
Commented Apr 13, 2019 at 21:34 — Ian McLaird
– Ian McLaird, Commented Apr 13, 2019 at 21:34
filter() uses expressions, filter_by() uses parameters

John Roper
– John Roper

2019-04-14 01:03:02 +00:00
Commented Apr 14, 2019 at 1:03 — John Roper
– John Roper, Commented Apr 14, 2019 at 1:03

Light.G · Accepted Answer · 2019-04-13 17:00:02Z

3

You missed to add changed object to current session.

And try the following snippet.

blend = db.session.query(Blend).filter_by(old_ID=row[4]).first()
if blend:
    blend.imagefolder = "/".join((row[16].split("/")[4:])[:-1])
    blend.images.append(ntpath.basename(row[16]))
    db.session.add(blend)
    db.session.commit()

edited Apr 13, 2019 at 17:00

answered Apr 13, 2019 at 0:52

Light.G

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1 Comment

John Roper Over a year ago

I tried that and it gave an error saying it was already in the session.

Тарасов Петр · Accepted Answer · 2025-03-25 18:08:36Z

0

you can't use .append with arrays. SQLAlchemy doesn't see changes this way.
You should do this instead:

blend.images = blend.images + [ntpath.basename(row[16])]

Maybe you still need this after 6 years of waiting xD

answered Mar 25 at 18:08

Тарасов Петр

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