added parent_id to locations

[vaneuk]

Hey
I'm working on adding parent_id to locations and looking for an advise.

There is an issue with parent_id=null for data sources. It is treated as "0" and hence "parent_id" is not added to the API query and we are reading multiple locations instead of one. Failed test output:

 data_source_netbox_location_test.go:13: Step 2/2 error: Error running post-apply plan: exit status 1
        
        Error: expected one location, but got 2
        
          with data.netbox_location.by_name_and_parent,
          on terraform_plugin_test.tf line 24, in data "netbox_location" "by_name_and_parent":
          24: data "netbox_location" "by_name_and_parent" {
        
        
        Error: expected one location, but got 2
        
          with data.netbox_location.by_name_and_site_and_parent_id,
          on terraform_plugin_test.tf line 29, in data "netbox_location" "by_name_and_site_and_parent_id":
          29: data "netbox_location" "by_name_and_site_and_parent_id" {
        
        
        Error: expected one location, but got 2
        
          with data.netbox_location.by_slug,
          on terraform_plugin_test.tf line 39, in data "netbox_location" "by_slug":
          39: data "netbox_location" "by_slug" {

location name is unique only per parent. So we can have multiple locations beneath different parents.
parent_id=null means locations without parents (aka root locations).

[fbreckle]

Just making sure I get this right:

You are saying that we need the option to search for parent_id = null, but the api client then drops that part in the actual query because of omitempty? In that case, this has to be changed in https://github.com/fbreckle/go-netbox . This happened a lot in other resources as well.

[fbreckle]

Superseded by #548