Documentation

Check if a value exists

Use the exists operator to check if a row record contains a column or if a column’s value is null.

(r) => exists r.column

If you’re just getting started with Flux queries, check out the following:

Use exists with row functions ( filter(), map(), reduce()) to check if a row includes a column or if the value for that column is null.

Filter null values

from(bucket: "example-bucket")
    |> range(start: -5m)
    |> filter(fn: (r) => exists r._value)

Map values based on existence

from(bucket: "default")
    |> range(start: -30s)
    |> map(
        fn: (r) => ({r with
            human_readable: if exists r._value then
                "${r._field} is ${string(v: r._value)}."
            else
                "${r._field} has no value.",
        }),
    )

Ignore null values in a custom aggregate function

customSumProduct = (tables=<-) => tables
    |> reduce(
        identity: {sum: 0.0, product: 1.0},
        fn: (r, accumulator) => ({r with
            sum: if exists r._value then
                r._value + accumulator.sum
            else
                accumulator.sum,
            product: if exists r._value then
                r.value * accumulator.product
            else
                accumulator.product,
        }),
    )

Check if a statically defined record contains a key

When you use the record literal syntax to statically define a record, Flux knows the record type and what keys to expect.

  • If the key exists in the static record, exists returns true.
  • If the key exists in the static record, but has a null value, exists returns false.
  • If the key does not exist in the static record, because the record type is statically known, exists returns an error.
import "internal/debug"

p = {
    firstName: "John",
    lastName: "Doe",
    age: 42,
    height: debug.null(type: "int"),
}

exists p.firstName
// Returns true

exists p.height
// Returns false

exists p.hairColor
// Returns "error: record is missing label hairColor"

Was this page helpful?

Thank you for your feedback!


Select your region

Linux Package Signing Key Rotation

All signed InfluxData Linux packages have been resigned with an updated key. If using Linux, you may need to update your package configuration to continue to download and verify InfluxData software packages.

For more information, see the Linux Package Signing Key Rotation blog post.

InfluxDB Cloud backed by InfluxDB IOx

All InfluxDB Cloud organizations created on or after January 31, 2023 are backed by the new InfluxDB IOx storage engine. Check the right column of your InfluxDB Cloud organization homepage to see which InfluxDB storage engine you’re using.

If powered by IOx, this is the correct documentation.

If powered by TSM, see the TSM-based InfluxDB Cloud documentation.

InfluxDB Cloud backed by InfluxDB TSM

All InfluxDB Cloud organizations created on or after January 31, 2023 are backed by the new InfluxDB IOx storage engine which enables nearly unlimited series cardinality and SQL query support. Check the right column of your InfluxDB Cloud organization homepage to see which InfluxDB storage engine you’re using.

If powered by TSM, this is the correct documentation.

If powered by IOx, see the IOx-based InfluxDB Cloud documentation.

State of the InfluxDB Cloud (IOx) documentation

The new documentation for InfluxDB Cloud backed by InfluxDB IOx is a work in progress. We are adding new information and content almost daily. Thank you for your patience!

If there is specific information you’re looking for, please submit a documentation issue.