reference Yang objects with Python code

[mastedarq]

I've got an issue with referencing Yang objects from Python.

I'm capable to reference leaf objects as long as they're defined within "global" service space, but as soon as I move them into the list object I've no clue how to "reach" them.

Please find scrap of my Yang model below:

module ACCESS-LISTS {
  ... omitted std cfg
  list ACCESS-LISTS {
    ... omitted std cfg

    list acl {
      key acl_name;

      leaf acl_name {
        type string;
     }

      leaf acl_id {
        type uint32;
      }

      leaf line {
        type string;
      }
    }
  }
}

Now my piece of Python code:

        vars = ncs.template.Variables()
        vars.add('ACL_NAME', service.acl.acl_name)
        vars.add('ID', service.acl.acl_id)
        vars.add('LINE', service.acl.line)

The rest of the Python file is as generated by the ncs-maker, so the servicepoint and Callbacks, etc are in place.

When I have Yang objetcs (acl_name, acl_id, line) in global space (not inside acl list) I'm able to reference them by using below Python code:

        vars = ncs.template.Variables()
        vars.add('ACL_NAME', service.acl_name)
        vars.add('ID', service.acl_id)
        vars.add('LINE', service.line)

But as soon as I place them inside above mentioned list and modify Python code accordingly, I've got below response when commiting ACCESS-LISTS service on NSO:

Aborted: Python cb_create error. 'List' object has no attribute 'acl_name'

I'm doing something wrong, just please give me some directions so I can find out what.

I was also trying to check the type of those access-lists to figure out how to maybe reference them, but the only thing I was able to find was:

type(r13.config.cisco_ios_xr__ipv4.access_list.named_acl)
ncs.maagic.List

R13 is my test router.

I went through maagic.List description, but none of the available attributes was working when I was trying it in my Python code.

[omz]

Hi

have a look at below posts .. may be helpful. 

https://community.cisco.com/t5/nso-developer-hub-discussions/python-code-to-reference-yang-objects/m-p/3445045

https://community.cisco.com/t5/nso-developer-hub-discussions/accessing-a-a-yang-list-in-python-code/m-p/3865650

[mastedarq]

I've read them both, but was unable to find out how to solve my issue.

[tcragg1 · Accepted solution]

To directly access the child nodes of a list, you need to either specify the list key to access the nodes within a specific list member, or iterate over the list using a for loop to apply some logic to all members of the list like the following example:

for acl_obj in service.acl:
    vars = ncs.template.Variables()
    vars.add('ACL_NAME', acl_obj.acl_name)
    vars.add('ID', acl_obj.acl_id)
    vars.add('LINE', acl_obj.line)

If you do use a for loop to iterate over multiple ACLs, you will need to include the template apply logic within the same for loop (otherwise I think the end result will be that only the last entry in the list actually gets passed to the template).

[mastedarq]

Yes, it works now. Thank You.