Cut the beginning and ending of a tag value

Fluxlang
1

Hey,

I’m calling all the possible tag values with the following query:

import “influxdata/influxdb/v1”

v1.tagValues(

bucket: "MyBucket",

tag: "Generic_Name",

predicate: (r) => true,

start: -1d

)

The tag values returned look like this:

“Machine_Number/Name1/Name2/Sensortype/Unit”

What i want to achive is that i cut out the Sensortype and Unit.
I tried to achive this with the strings.trimright() function

But i was only able to cut out a specificly defined text. The Problem is that every unit and every sensortype is called differently.

Is there a way to make this trimming funktion dynamical so that it trims everything to the second / from the right?

2

Hello @Patse,
Is the front end of your text the same?
You could use regex instead.

I like to use this tester

I found a solution but I don’t like it:

import "array"
import "strings"

word = "Machine_Number/Name1/Name2/Sensortype/Unit"

array.from(rows: [{_time: now(), _value: word}])

|> map(fn: (r) => ({ r with suffix: strings.trimPrefix(v: r._value, prefix: "Machine_Number/Name1/Name2/")

}))

|> map(fn: (r) => ({ r with prefix: strings.trimSuffix(v: r._value, suffix: r.suffix)

}))

I’m sharing with the Flux team too in case there are any other solutions I’m not aware of.

3

Hey, the front and the back end of my tag values are different for each machine and sensor type.
The only thing that is identical is the number of “/” in between each part of my tag value.
That’s why i hoped that there is a possibility to say trim until the second “/” from the right.

4

Hello @Patse,
I think you can say that with regex. I’m just not sure how.

5

@Anaisdg

I was trying to do something similar, cutting the date off a string x-y-z_20220101 and the search led me to this post.

This doesn’t solve the original problem, but might help anyone else trying to cut the last part of a string containing delimiters, where the string is variable in length:

import "array"
import "strings"

word = "Machine_Number/Name1/Name2/Sensortype/Unit"

array.from(rows: [{_time: now(), _value: word}])
 |> map(fn: (r) => ({
      r with
      start: strings.lastIndex(v: r._value, substr: "/") + 1,
      end: strings.strlen(v: r._value),
    })
  )
  |> map(fn: (r) => ({_time:r._time, _value: strings.substring(v: r._value, start: r.start, end: r.end) }))
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