70 lines
3.0 KiB
Markdown
70 lines
3.0 KiB
Markdown
---
|
|
title: Using reduce() to construct a JSON.
|
|
description: >
|
|
Learn how to send multiple points with `http.post()` by creating a JSON object with `reduce()`.
|
|
menu:
|
|
resources:
|
|
parent: How-to guides
|
|
weight: 105
|
|
---
|
|
|
|
## Send data in JSON body with `http.post()`
|
|
Use the [reduce()](/flux/v0.x/stdlib/universe/reduce/) function to create a JSON object to include as the body with `http.post()`.
|
|
|
|
1. Import both the [array](/flux/v0.x/stdlib/array/) package to query data and construct table(s), and the [http package](/flux/v0.x/stdlib/http/) 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](/influxdb/v2/query-data/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:
|
|
|
|
| field | tag |
|
|
| :-------------------- | :----------------------------- |
|
|
| example-field:["3"4"1 | {example-tag-key:["bar"bar"bar |
|
|
|
|
4. Use the [map()](/flux/v0.x/stdlib/universe/map/) function to combine the two components together into a JSON object, and then use a second `yield()` function to store this object as `final JSON`. This table looks like:
|
|
|
|
| field | tag | final |
|
|
| :-------------------- | :----------------------------- | :------------------------------------------------------- |
|
|
| 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 sent the JSON to. In this example, we use [Post Test Server](https://ptsv2.com/) as URL to send the JSON to, and test the `http.post()` function.
|
|
|
|
```js
|
|
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),
|
|
)
|
|
```
|
|
|
|
|