lookup configmap value in helm template - kubernetes

Question

Say I have a configmap like this, and I want to get the value(12301) of version 123v1 in map_a, what is the correct way?
apiVersion: v1
kind: ConfigMap
metadata:
name: myconfig
namespace: default
data:
test.yml: |
map_a:
"123v1":
"Version": 12301
"Type": "abc"
......
Here is my attempts:
apiVersion: v1
kind: ConfigMap
metadata:
name: test-config
data:
{{- $configmap := (lookup "v1" "ConfigMap" "default" "myconfig") }}
{{- if $configmap }}
{{- $models := get $configmap.data "test.yml" }}
version: {{ $models.map_a.123v1.Version }}
{{- end }}
$ helm template .
install.go:173: [debug] Original chart version: ""
install.go:190: [debug] CHART PATH: /root/test-lookup
Error: parse error at (test-lookup/templates/config.yaml:9): ".123v"
helm.go:88: [debug] parse error at (test-lookup/templates/config.yaml:9): ".123v"

Answer 1

The pipe symbol at the end of a line in YAML signifies that any indented text that follows should be interpreted as a multi-line scalar value. See the YAML spec. This is also mentioned in the helm doc |-
{{ $models }} is a value behind a pipe symbol of myconfig>data>test.yml.
So, the value of the expression {{ $models }} is a string instead of a map. In other words, {{ $models. map_a }} is an illegal operation.
The real value of {{ $models }} is a multi-line string, the string content is:
map_a:
"123v1":
"Version": 12301
"Type": "abc"
This can work here, of course the result is not what you want:
apiVersion: v1
kind: ConfigMap
metadata:
name: test-config
data:
{{- $configmap := (lookup "v1" "ConfigMap" "default" "myconfig") }}
{{- if $configmap }}
{{- $models := get $configmap.data "test.yml" }}
version: {{ $models | quote }}
{{- end }}
output：
apiVersion: v1
data:
version: |
map_a:
"123v1":
"Version": 12301
"Type": "abc"
kind: ConfigMap
metadata:
annotations:
...
So in order to achieve your purpose, you have to operate {{ $models }} in accordance with the method of operating strings.
config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: test-config
data:
{{- $configmap := (lookup "v1" "ConfigMap" "default" "myconfig") }}
{{- if $configmap }}
{{- $models := get $configmap.data "test.yml" }}
{{- range ( split "\n" $models) }}
{{- if ( contains "Version" .) }}
version: {{ (split ":" .)._1 | trim | quote }}
{{- end }}
{{- end }}
{{- end }}
output:
apiVersion: v1
data:
version: "12301"
kind: ConfigMap
metadata:
annotations:
...