Variable value as yaml key in helm chart

Question

I want to choose config section from values.yaml by setting a variable in helm command line.

example part of values.yaml:

aaa:
  x1: "az1"
  x2: "az2"
bbb:
  x1: "bz1" 
  x2: "bz2"

example part of configmap.yaml

data: 
  {{ .Values.outsideVal.x1 }}

Expected result should looks like this

   data:
     az1

Test helm output

helm template --set outsideVal=aaa mychart

And got this error

Error: render error in "./templates/configmap.yaml": template: ./templates/configmap.yaml:21:12: executing "./templates/configmap.yaml" at <.Values.outsideVal.x...>: can't evaluate field x1 in type interface {}

So the question is how get the result as expected?

Answer

I suspect you're looking for the text/template index function, which can look up a value in a map by a variable key.

{{ (index .Values .Values.outsideVal).x1 }}