Persistence

by andrea 00:42 0 commenti

There are a number of services providing persistence in a simple way, such as firebase or parse, just to mention few of them. Actually both of them are much more than persistence services!!!

However, for the sake of simplicity, here we will use json-db-node-red

In this simple example, the json data from openweather are stored in the JsonDB

The following is the content of the .json file under ~/.node-red/JsonDB/.json

{"prova":{"weather":"Clouds","detail":"scattered clouds","tempk":289.399,"tempc"
:16.1,"humidity":91,"maxtemp":289.399,"mintemp":289.399,"windspeed":4.23,"winddi
rection":125.006,"location":"Trevi","sunrise":1462766140,"sunset":1462817874,"cl
ouds":44,"description":"The weather in Trevi at coordinates: 41.9, 12.49 is Clou
ds (scattered clouds)."}}

As you can see the path prova, specified as a parameter of the JsonDB, is  the JSON object. To access the fields is sufficient to write msg.payload.<name of the properiy> as an example msg.payload.weather will return Clouds.