What is the Web2py way of making session variables unique to one
browser tab? This example illustrates the problem.
Model:
db.define_table('products', Field('quantity_on_hand', 'integer'))
db.define_table('jobs', Field('job_yield', 'integer'),
Field('product_id', db.products))
When a user updates the job_yield field, the jobs controller also
needs to update quantity on hand in the products table. Usually one
would use a session variable something like this.
def edit():
# fetch current job yield
old_job_yield = db.jobs[request.vars(0)].job_yield
# save it in a session
session.old_job_yield= old_job_yield
...
if form.accepts(session,request):
if request.post_vars.job_yield != session.old_job_yield:
yield_delta = request.post_vars.job_yield -
session.old_job_yield
# assume we magically fetch related product id, then
old_quantity_on_hand =
db.products[product_id].quantity_on_hand
new_quantity_on_hand = old_quantity_on_hand +
yield_delta
db(db.products.id==product_id).update(quantity_on_hand=new_quantity_on_hand)
The problem arises if the user edits a different job in a different
tab. Because there is only one instance of session.old_job_yield, the
edit action in the other tab will overwrite it.
What is the Web2py way of handling this problem?
Thanks,
Cliff Kachinske
