Flask-SQLAlchemy: How to conditionally insert or update a row

Question

My application uses a combination of Flask, Flask-SQLAlchemy, Flask-WTF and Jinja2.

In its current incarnation, I have a settings table. The table will only have one rec

Answer 1

Once your form is validated etc,

To add a new record:

new_provider = Provider(form.rssfeed.data)
db.session.add(new_provider)
db.session.commit()

To update an existing record:

existing_provider = Provider.query.get(1) # or whatever
# update the rssfeed column
existing_provider.rssfeed = form.rssfeed.data
db.session.commit()

The trick in updating is that you just have to change the particular field and do a commit. rest is taken care by the db session. I think you are using the merge function which is now deprecated in SQLAlchemy.

Answer 2

I have managed to solve the problem doing these changes to the view.py file:

@app.route('/settings', methods=["GET","POST"])
def settings():
    """ show settings """
    provider = Provider.query.get(1)
    form = SettingsForm(request.form,obj=provider)

    if request.method == "POST" and form.validate():
        if provider:
            provider.rssfeed = form.rssfeed.data
            db.session.merge(provider)
            db.session.commit()
            flash("Settings changed")
            return redirect(url_for("index"))
        else:
            provider = Provider(form.rssfeed.data)
            db.session.add(provider)
            db.session.commit()
            flash("Settings added")
            return redirect(url_for("index"))
    return render_template("settings.html", form=form)