Thanks Anthony. Here's the explanation of what I intend to do. 1) D is a dataset (tuple of dicts) obtained from MySQL. I am using a 3rd party lib viz. 'DABO' for database interaction + business-logic tier. So, D is generated by controller function.
2) It is passed to View where HTML elements are populated by the data from this dataset. 3) User interacts with HTML elements & changes the data. 4) Dynamically, the dataset is altered after user-interaction with HTML elements. 5) After hitting 'Save' button, the dataset is passed to controller function for handling add/update/delete on related DB tables. This way, a dataset is unique for every session. I hope my logic is now more clear. I appreciate your hint on using session object for storing this dataset. Any thoughts / suggestions/ corrections please. --- Vineet On Feb 11, 6:22 pm, Anthony <[email protected]> wrote: > It might help if you provide a little more detail regarding what D is and > what kind of processing is going on. Why do you create D in the controller > but newD in the view? Does D get used anywhere before newD is created? > Could you just create newD in the controller as well? Is D/newD unique per > user/session, or is it the same across all sessions? > > As it is, it looks like you could get a race condition. An initial request > to func1 leaves newD in my_pckl.p. Then before the first Ajax request to > func2, a second request to func1 overwrites my_pckl.p with D, and then the > first Ajax request to func2 reads D out of my_pckl.p before the view > changes it to newD (i.e., so the Ajax request gets D instead of newD). The > problem is worse if the value of newD depends on the user/session -- since > you always use the same filename, the newD for one user could be > overwritten by a func1 request from another user before the first user's > func2 Ajax request. The whole process will be slowed down a bit by the file > writing/reading as well. > > If newD is the same for all users, you might store it in cache.ram rather > than writing it to a file -- that will be faster and you won't have to > worry about doing the pickling yourself. If newD is specific to each user, > then just store it in the session (again, you won't have to pickle it > yourself). > > Anthony > > On Saturday, February 11, 2012 4:31:08 AM UTC-5, Vineet wrote: > > > From View, I am calling server side controller function via web2py's > > ajax function with ':eval' > > So far, so good. > > > Further I need to return a dict from this ajax controller (in addition > > to "return js"), > > Then access this dict in View & process it. > > Finally, return dict to another controller for server side processing. > > > ++++++++++++++++++++++++++++++++++++++ > > I am doing it like this. > > > def func1(): > > D = ({1:'a', 2:'b'}, {3:'c', 4:'d'}) > > cPickle.dump(D, open( "my_pkcl.p", "wb")) > > return dict() > > > This D is accessed in 'View' and processed. > > > #### (Why I am not using return dict(D=D)? > > #### It is explained at the end.) > > > {{newD = cPickle.load(open( "my_pkcl.p", "rb" ))}} > > {{for i in newD:}} > > .......processing statements....... > > {{pass}} > > > After processing newD, it is again pickled with same filename. > > {{cPickle.dump(newD, open( "my_pkcl.p", "wb" ) )}} > > > Then ajax function is called-- > > ajax("{{=URL('func2)}}", [], ":eval"); > > > def func2(): > > # access the D which has been changed by 'View' code > > changedD = cPickle.load( open( "my_pkcl.p", "rb" ) ) > > ... > > ... > > process changedD as per requirement > > > ++++++++++++++++++++++++++++++++++++++ > > Why I am not using return dict(D=D)? > > While calling 'func2' via web2py's ajax function, I can't pass the > > Dict (or any other python object) as argument or vars. > > So I resorted to cPickle it. > > +++++++++++++++++++ > > My question is:-- > > I am cPickling in controller & loading (unpickling) in View. > > After processing in view, cPickling it & again loading (unpickling) in > > controller. > > > Is it OK or is it weired / horrible (considering speed & good coding > > practice) ? > > If not OK, how do I do it with any alternative method ? > > > Thanks, > > > Vineet > >
