Retrieve one (last) value from influxdb - json

Question

I'm trying to retrieve the last value inserted into a table in influxdb. What I need to do is then post it to another system via HTTP.
I'd like to do all this in a bash script, but I'm open to Python also.
$ curl -sG 'https://influx.server:8086/query' --data-urlencode "db=iotaWatt" --data-urlencode "q=SELECT LAST(\"value\") FROM \"grid\" ORDER BY time DESC" | jq -r
{
"results": [
{
"statement_id": 0,
"series": [
{
"name": "grid",
"columns": [
"time",
"last"
],
"values": [
[
"2018-01-17T04:15:30Z",
690.1
]
]
}
]
}
]
}
What I'm struggling with is getting this value into a clean format I can use. I don't really want to use sed, and I've tried jq but it complains the data is a string and not an index:
jq: error (at <stdin>:1): Cannot index array with string "series"
Anyone have a good suggestion?

Answer 1

Pipe that curl to the jq below
$ your_curl_stuff_here | jq '.results[].series[]|.name,.values[0][]'
"grid"
"2018-01-17T04:15:30Z"
690.1
The results could be stored into a bash array and used later.
$ results=( $(your_curl_stuff_here | jq '.results[].series[]|.name,.values[0][]') )
$ echo "${results[#]}"
"grid" "2018-01-17T04:15:30Z" 690.1
# Individual values could be accessed using "${results[0]}" and so, mind quotes
All good :-)

Answer 2

Given the JSON shown, the jq query:
.results[].series[].values[]
produces:
[
"2018-01-17T04:15:30Z",
690.1
]
This seems to be the output you want, but from the point of view of someone who is not familiar with influxdb, the requirements seem very opaque, so you might want to consider a variant, such as:
.results[-1].series[-1].values[-1]
which in this case produces the same result, as it happens.
If you just want the atomic values, you could simply append [] to either of the queries above.