Can a container inside a grouping be augmented in YANG?

YANG
1

The first module contains this:

    module a
    {
        namespace "my:namespace";
        prefix a;
        grouping mygrouping
        {
            container firstcontainer {
                list modules {
                    leaf firstmodule;
                    leaf secondmodule;
                }    
            }
        }
    }

Now I want to augment it in the second module as follows:

module b
{
    namespace "my:namespace";
    prefix a;
    import b {
        prefix b;
    }
    augment "/b:mygrouping/b:firstcontainer/b:modules"{
        leaf thirdmodule;
    }
}

This does not work, apparently because a grouping cannot be augmented. But there must be a way, since what I really want to extend is the list, not the grouping itself.

Is there another way to have the intended result using another way ?

2

Grouping are a conceptual aggregation of nodes, and they do not exist in the final schema i.e. when you use a uses xyz_grouping clause in schema, the compiler internally copies all the elements of xyz_grouping within it.

If you do not use any uses statement the grouping has no effect on final schema.

So in your example

module a
{
   .
   .
   .
    container commands-a {
        uses mygrouping;
    }
}

This would be equivalent of writing this from POV of compiler

module a
{
   .
   .
   .
    container commands-a {
            container firstcontainer {
                list modules {
                    leaf firstmodule;
                    leaf secondmodule;
                }    
          }        
    }
}

Then you can augment leaf thirdmodule onto that node that exist in the schema (in this case commands-a)

i.e.

module b
{
    namespace "my:namespace";
    prefix b;
    import  a {
        prefix a ;
    }
    augment "/a:commands-a/a:firstcontainer/a:modules"{
        leaf thirdmodule;
    }
}

(Disclaimer: The statements about confdc compiler are from my understanding by using it. I have not seen the code and hence may be wrong).

3

Another option is that augment can be a substatement on the uses statement, so rather than have a separate standalone augment statement, you can at the point where you “use” the grouping, also augment it whatever way you want.

4

Yes this works for me. Thank you.

But what if I want to augment an enumeration which is inside the grouping ?

5

You can’t augment a type.

If your requirement is to have dynamic enumerations (i.e. be able to add new enumerations), you should replace the enumeration with an identityref type. Refer to: https://tools.ietf.org/html/rfc8407#section-4.11.1 for an example.

Or, if you want to restrict certain values, you can use the ‘if-feature’ statement, or a ‘must’ statement.