I could think a lot of different ways to mark null "value": n/a, NA, n.a., None, NULL and so on. If csv file is used on another applications than on import data to web2py itself, then there should be a way to manually decide, how null should be marked and which data should be interpreted as null. So i would set an optional argument, which default is '<NULL>', but is changeable.
-Marko On 22 joulu, 12:38, mdipierro <[email protected]> wrote: > I have rewritten the CSV io functions (in trunk). Now they work > better, are more portable and should work on GAE. > They also have one cool new feature: > > Consider this: > > db=SQLDB('sqlite:memory:') > db.define_table('t1',SQLField('name'),SQLField('test')) > db.define_table('t2',SQLField('a',db.t1),SQLField('name')) > db.t1.insert(name='max') > db.t2.insert(a=1,name='tim') > > The t2 record references the t1 record. Let's dump both tables: > > open('t1.csv','w').write(db(db.t1.id>0).select()) > open('t2.csv','w').write(db(db.t2.id>0).select()) > > They contain: > > t1.id,t1.name > 1,max > t2.id,t2.a,t2.name > 1,1,tim > > Now reimport, in the naive way, > > db.t1.import_from_csv_file(open('t1.csv','r')) > db.t2.import_from_csv_file(open('t2.csv','r')) > > and you get > > t1.id,t1.name > 1,max > 2,max > t2.id,t2.a,t2.name > 1,1,tim > 2,1,tim > > Nothing new here. The record t2.id==2 references t1.id==1 instead of > t1.id==2. This is not what one would expect since the new t2 record > should reference the new t1 record. > > To fix this you can instead import in the following way: > > remap={} > db.t1.import_from_csv_file(open('t1.csv','r'),remap) > db.t2.import_from_csv_file(open('t2.csv','r'),remap) > > and you get > > t1.id,t1.name > 1,max > 2,max > t2.id,t2.a,t2.name > 1,1,tim > 2,2,tim > > Now t2.id==2 reference t1.id==2 instead of t1.id==1. This is one would > expect. > > Summary: if you need to import multiple tables that reference each > other, pass a dictionary (the same) to all calls to > import_from_csv_file and web2py will take care of remapping the > reference indices. The dictionary is used to store the mapping between > the old 'id' and the new 'id'. > > This can be used for remote database synchronization using CSV. > > None is serialized as <NULL> to avoid csv shortcomings. > > Massimo --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py Web Framework" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
