How to reference to an object with 3 attributes

Hi folks.
I’m trying to create 3 kubernetes clusters and then reference their IDs to their node-pools. The clusters are being referenced by the subnet_ids using for_each. So basically one cluster per subnet_id is being created. Next step is to create one node-pool based on the cluster_id. But the problem here is that I cannot access to the attributes of the clusters. To have a better understanding, I share the code.

K8s cluster per subnet_id:

resource "opentelekomcloud_cce_cluster_v3" "cluster_k8s" {
  for_each = var.subnet_id

  name        = join("-", ["cluster", each.value])#"cluster-${var.subnet_id}" 
  cluster_type           = "VirtualMachine"
  flavor_id              = var.flavor_id
  vpc_id                 = var.vpc_id
  subnet_id              = each.value 

Node Pool definition:

resource "opentelekomcloud_cce_node_pool_v3" "node_pool_dev" {
  for_each = opentelekomcloud_cce_cluster_v3.cluster_k8s["id"]

  cluster_id         = each.value 
  name               = "opentelekomcloud-cce-node-pool-test"

And the error I’m getting:

Error: Invalid index
│   on modules/cce/ line 50, in resource "opentelekomcloud_cce_node_pool_v3" "node_pool_dev":
│   50:   for_each = opentelekomcloud_cce_cluster_v3.cluster_k8s["id"]
│     ├────────────────
│     │ opentelekomcloud_cce_cluster_v3.cluster_k8s is object with 3 attributes
│ The given key does not identify an element in this collection value.

It would be appreciated if someone can give me a clue.

This reference lacks use of the map elements created with the subnet_id keys.
So you would need something like (not tested):

for_each = toset(flatten([for k,v in opentelekomcloud_cce_cluster_v3.cluster_k8s :]))

Usually you get a good understanding of the data structures using outputs of the these.