Edit Web2py json output for Google Chart -

i have managed google charts plugin (http://www.web2pyslices.com/slice/show/1721/google-charts-plugin) work web2py application. using json example data (data hard coded default.py).

i struggling using own data. chart not work json data returns information as:

{"data": [["2014-03-28", 1000], ["2014-03-25", 1100]]} 

when hardcode data titles, chart works:

data = [['date','sales'],["2014-03-28",1000],["2014-03-25",1100]] 

this returns json as:

{"data": [["date", "sales"], ["2014-03-28", 1000], ["2014-03-25", 1100]]} 

the code is:

def return_data(): data = [['date','sales'],["2014-03-28",1000],["2014-03-25",1100]] return dict(data=data) 

below code using in default.py return information database, query works, it's chart doesn't!:

def return_data():     sales = db().select(db.sales.quantity, db.sales.date) data = [[row.date,row.quantity] row in sales] return dict(data=data) 

somehow, think need add 'date' , 'sales' labels start of json data have not managed - think need sort of encode? - need use simplejson or can done without??

many thanks