YANG enum constraints

[Johnny Karms Pedersen]

Hi all,

A quick YANG question; Consider a list of sites. These sites can be one of three types; hub, branch or transit. Only one hub can exist, but multiple branches and transits are allowed. How would I create this constraint within my YANG model?

list sites {

  key site-id;

  leaf site-id {

    mandatory true;

    type uint16;

  }

  leaf site-type {

    type enumeration {

      enum hub;

      enum transit;

      enum branch;

    }

  }

}

[vleijon · Accepted solution]

You use a must expression. So it looks something like

  must "count(/sites[site-type='hub']) < 2";

[Johnny Karms Pedersen]

 Thanks :)

I get this error;

warning: The 'must' expression will fail: the node 'sites' from module 'wan' (in node 'site-type' in module 'wan' from 'wan') is not found.

I've added this to the module;

list sites {

  key site-id;

  leaf site-id {

    mandatory true;

    type uint16;

  }

  leaf site-type {

    type enumeration {

      enum hub;

      enum transit;

      enum branch;

    }

    must "count(/sites[site-type='hub']) < 2" {

     error-message "Only one HUB can be present";

    }

  }

}

[Johnny Karms Pedersen · Accepted solution]

Apparent I had an issue with the path. Solved it by using this syntax instead:

must "count(current()/../../sites[site-type='hub']) < 2"

The sites were in a list of WANs, but the path {/wan/sites[site-type]} didn't work for me either. Probably since I would have to reference the key of the WAN list (name). I dunno, but the above works.. :)