Proper syntax for nodeSelector values in apps launch?

Hello,
I’m launching the ‘elasticsearch’ app from the helm catalog onto a cluster and would like to constrain which nodes it runs on. Under “Detailed Descriptions” it mentions these Configuration parameters:
client.nodeSelector {}
master.nodeSelector {}
data.nodeSelector {}

Based on the Rancher docs here, the values should adhere to the format allowed by helm --set argument.
So if I want to constrain the pods to, say nodes with the “env=dev” key/pair, I would add:

{“env”:“dev”}

But this fails with:
v1.Deployment.Spec: v1.DeploymentSpec.Template: v1.PodTemplateSpec.Spec: v1.PodSpec.NodeSelector: ReadMapCB: expect { or n, but found [, error found in #10 byte of …|elector":["“env”:|…, bigger context …|ityContext":{“privileged”:true}}],“nodeSelector”:["“env”:“dev”"],“restartPolicy”:“Always”,"sched|…

…what is the proper syntax for values of type {} ?

Looks like this is a compatibility problem with the chart version Rancher is trying to deploy, and Kubernetes 1.17.3.

I ended up installing elasticsearch from here:

Quick and easy, able to setup node affinity without any problem.