Json filter

[Luca Ferrari]

Hello,

I’d like to apply a filter on an attribute of a json documents. For example I 
have a Document like that 
{
    "time": "2014-08-15T21:00:00.000",
    "longitude": "136.048724",
    "latitude": "33.8144776",
    "altitude": "NULL",
    "rainfall": 0,
    "city_name": "Tokyo",
    "station_name": "NULL"
},
{
    "time": "2014-08-15T21:40:00.000",
    "longitude": "139.0634281",
    "latitude": "36.3894816",
    "altitude": "NULL",
    "rainfall": 6.5,
    "city_name": "Tokyo",
    "station_name": "NULL"
},
{
    "time": "2014-08-15T21:50:00.000",
    "longitude": "138.4768306",
    "latitude": "36.2488683",
    "altitude": "NULL",
    "rainfall": 8,
    "city_name": "Tokyo",
    "station_name": "NULL"
}
And I need to filter the data with rainfall > 6.

How can I manage the JSON parser and the filter?

Thanks
Luca