Unable to retrieve subnet_Id - Terraform

I've created a subnet via Terraform

resource "azurerm_subnet" "subnet" {
  depends_on = [ azurerm_virtual_network.vnet ]
  name                 = lower("${var.application_name}-subnet-${var.location_short}-${var.environment}")
  resource_group_name  = azurerm_resource_group.networking_rg.name
  virtual_network_name = azurerm_virtual_network.vnet.name
  address_prefixes     = ["10.0.14.224/27"] #-> 10.0.14.255
  service_endpoints    = ["Microsoft.Storage"]
  delegation {
    name = "AFADelegation"
    service_delegation {
      name    = "Microsoft.DBforPostgreSQL/flexibleServers"
      actions = ["Microsoft.Network/virtualNetworks/subnets/join/action"]
    }
  }
}

I'm trying to output the subnetId of the above, so I can add my App Service into the private network, however, when outputting subnetId:

output "subnet_id" {
  value = module.private_network.subnet_id
}

I don't actually get an Id, instead I get

> "/subscriptions/2XXXXX-XXXX-XXX-XXXX-XXXXXX/resourceGroups/rg-networking-ae-dev-rg/providers/Microsoft.Network/virtualNetworks/rg-vnet-ae-dev/subnets/pn-subnet-ae-dev"

Why can't I get the Id?

> I don't actually get an Id, instead I get
> > "/subscriptions/2XXXXX-XXXX-XXX-XXXX-XXXXXX/resourceGroups/rg-networking-ae-dev-rg/providers/Microsoft.Network/virtualNetworks/rg-vnet-ae-dev/subnets/pn-subnet-ae-dev"

> Why can't I get the Id?

The value you obtained when you check the Subnet ID using terraform for subnet_id is the resource identifier of the subnet in Azure Resource Manager format. It includes the subscription ID, resource group name, virtual network name, and subnet name. it is still a valid identifier that uniquely identifies the subnet resource within Azure.

Output:

If you specifically want to extract only the subnet name from the resource identifier, you can use the element and split functions to extract the subnet base name.

Now, when you run terraform apply, the output subnet_id will contain the base name of the subnet extracted from the full resource identifier.

> Note: Subnet ID is a valid identifier in azure resource manager format. You can also verify the same value from the portal. If you want to use the Subnet ID elsewhere, you need to pass the entire value.

Output:

Reference: Query Data with Output Variables