New stuff in trunk:
1) customizable None/Null serialization
db(db.table.id>0).select().export_to_csv_file(open
('filename','w'),null='<NULL>')
db.table,import_from_csv_file(open('filename','r'),null='<NULL>')
2) complete database dump
db.export_to_csv_file(open('filename','w'))
for table in db.tables: db[table].truncate()
db.import_from_csv_file(open('filename','r'))
tables must be defined to be re imported.
Massimo
On Dec 22, 5:48 am, mmstud <[email protected]> wrote:
> 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
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