How to use to kubectl to patch statefulset envFrom - kubernetes

Question

I have a Kubernetes Statefulset and im using envFrom to add environment variables from ConfigMaps and Secrets, by defining configMapRefs and secretRefs in an 'extra-values.yaml' file and including that file in my helm install command.
The Statefulset.yaml snippet:
apiVersion: apps/v1
kind: StatefulSet
spec:
replicas: {{ .Values.replicaCount }}
template:
spec:
containers:
- name: {{ .Chart.Name | lower}}
envFrom:
{{- if .Values.envFrom }}
{{- toYaml .Values.envFrom | nindent 10}}
{{- end }}
The values.yaml file has a single envFrom: line with no children, and the extra-values.yaml file contains the configMapRefs and secretRefs:
envFrom:
- configMapRef:
name: my-configmap-name
- configMapRef:
name: another-configmap-name
- secretRef:
name: my-secret-name
- secretRef:
name: second-secret-name
The Helm install command:
helm install myapp /some-folder/myapps-chart-folder -f extra-values.yaml
What I want to do is install myapp without the extra-values.yaml file, and then use the kubectl patch command to add the configMapRefs and secretRefs to the statefulset and its pods.
I can manually do a kubectl edit statefulset to make these changes, which will terminate and restart the pod(s) with the correct environment variables.
But I cannot for the life of me figure out the correct syntax and parameters for the kubectl patch command, despite hours of research, trial, and error, and repeated headbanging. Help!

Answer 1

Thanks to mdaniel for the answer, which contains the clue to what I was missing. Basically, I completely overlooked the fact that the containers element is an array (because my statefulset only specified one container, duh). In all of the kubectl patch command variations that I tried, I did not treat containers as an array, and never specified the container name, so kubectl patch never really had the correct information to act on.
So as suggested, the command that worked was something like this:
kubectl patch statefulset my-statefulset -p '{"spec": {"template": {"spec": {"containers": [{"name":"the-container-name", "envFrom": [{"configMapRef":{"name":"my-configmap-name"}}, {"configMapRef":{"name":"another-configmap-name"}}] }] }}}}'