Updating database with for loop in Flask?

Question

I'm trying to automatize updates on database since I have a lot of columns. I have succeeded to display the database using for loop, but I have problem commiting changes to database:

@app.route('/listvehicle/<int:vehicle_id>/update', methods=['GET', 'POST'])
@login_required
def update_vehicle(vehicle_id):
    vehicle = Vehicle.query.get_or_404(vehicle_id)
    form = VehicleUpdateForm() 
    if form.validate_on_submit():
        for attr,value in vehicle.__dict__.items():
            for ia in form:
                if ia == attr:
                    vehicle.__dict__[attr] = form.__dict__[ia]
        db.session.commit()
        flash(f'The user has been updated', 'success')
        return redirect(url_for('listvehicle'))
    elif request.method == 'GET':
        for attr,value in vehicle.__dict__.items():
            for ia,iv in form.__dict__.items():
                if ia == attr:
                    iv.data = value
    return render_template('updatevehicle.html', form=form)

Any help with commiting changes to database?

Are you using sqlalchemy? why are you not using a ModelForm? — Rafael Barros
– Rafael Barros, Commented Jan 16, 2019 at 16:53

Rafael Barros · Accepted Answer · 2019-01-16 16:51:29Z

1

I would suggest you posting the Model and Form definitions, but without seeing it, I suggest you use a different approach, changing anything with double underscores (__dict__ for example) is highly discouraged.

I see an improvement that can be made simply by using setattr and iterating over the form data:

def update_vehicle(vehicle_id):
    vehicle = Vehicle.query.get_or_404(vehicle_id)
    form = VehicleUpdateForm() 
    if form.validate_on_submit():
        for fieldname, value in form.data.items():
            setattr(vehicle, fieldname, value)
        db.session.commit()
        flash(f'The user has been updated', 'success')
        return redirect(url_for('listvehicle'))
    elif request.method == 'GET':
        for attr,value in vehicle.__dict__.items():
            for ia,iv in form.__dict__.items():
                if ia == attr:
                    iv.data = value
    return render_template('updatevehicle.html', form=form)

answered Jan 16, 2019 at 16:51

Rafael Barros

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2 Comments

Senseikaii Over a year ago

Thank you a lot it works perfectly !! I don't know how the setattr() works ? Because when I look on python and try to see the attribut of my vehicle query I have an unboundField and I had no idea how to work with that

Rafael Barros Over a year ago

@Senseikaii setattr is the same as instance.attribute = "something", where you have the .attribute part as a variable with the name of the attribute.

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