Use reduce() to construct a JSON object

Use the reduce() function to create a JSON object to include as the body with http.post().

  1. Import both the array package to query data and construct a table, and the http package to transfer JSON over HTTP.

  2. Use array.from() to query data and construct a table, or use another method to query data with Flux.

  3. Use the reduce() function to construct a JSON object, and then use yield() to store the output of reduce(). This table looks like:

    fieldtag
    example-field:["3"4"1{example-tag-key:["bar"bar"bar

  4. Use the map() function to combine the two columns into a JSON object, and then use a second yield() function to store this object as final JSON. This table looks like:

    fieldtagfinal
    example-field:["3"4"1{example-tag-key:["bar"bar"bar{example-tag-key:["bar"bar"bar] , example-field:["3"4"1]}

  5. Use the findRecord() function to extract the value from the final column, the JSON.

  6. Use http.post() to specify a URL to send the JSON to. This example uses Post Test Server as the URL to send the JSON to and test the http.post() function.

import "array"
import "http"

data = array.from(
        rows: [
            {_time: 2020-01-01T00:00:00Z, _field: "example-field", _value: 3, foo: "bar"},
            {_time: 2020-01-01T00:01:00Z, _field: "example-field", _value: 4, foo: "bar"},
            {_time: 2020-01-01T00:02:00Z, _field: "example-field", _value: 1, foo: "bar"},
        ],
    )
    |> reduce(
            fn: (r, accumulator) => ({tag:accumulator.tag + "\"" + r.foo,
                                    field : accumulator.field + "\"" + string(v:r._value)
                                    }),
            identity: {tag: "{example-tag-key:[",
                    field: "example-field:[" }
    )
    |> yield(name: "output of reduce")
    |> map(fn: (r) => ({ r with tag: r.tag + "]" }))
    |> map(fn: (r) => ({ r with field: r.field + "]}" }))
    |> map(fn: (r) => ({ r with final: r.tag + " , " + r.field}))
    |> yield(name: "final JSON")
    |> findRecord(
        fn: (key) => true,
        idx: 0,
        )

http.post(
    url: "https://ptsv2.com/t/c4x38-1656014222/post",
    headers: {"Content-type": "application/json"},
    data: bytes(v: data.final),
    )

Was this page helpful?

Thank you for your feedback!