[web2py] db.table.update(f1='...') fine, but why I can't pass a dict : db.table.update({'f1':'...'})

[Richard]

Hello,

I would like to update some field with the out put of a web2py query that I 
can transform as dict like this :

db(...).select(db.table1.field1, db.table1.field2).first().as_dict()

Then I would do that :

db(...).update(db(...).select(db.table1.field1, 
db.table1.field2).first().as_dict())

Mistake buzzer trigger!!! : update() takes exactly 1 argument (2 given)

Under 1.99.4

Why I can't pass a dict to the update function?

Thanks

Richard