Displaying single record

YANG
1

Hello Team,

I want to display a table that can have only a single record. So basically, there is no specific key required. Please suggest an appropriate yang construct to achieve this.

I have a C structure similar to this to be displayed in a show command (show table details):

struct table {
  char interface[128];
  char fname[128];
  uint32 num-pkts;
};

Regards,
Saswat

2

Hello Saswat,

i think presence container (see RFC) fits this use case…

It’s like single list-entry with no extra key leaves.
It can exist/not exist, and has only non-key leaves - so something like this:

container table {
  presence: "explanation for this presence...";
  leaf interface { type string { length "1..127"; } }
  // COMMENT: 127/128 - depending on your type rules - string null termination
  leaf fname { type string { length "1..127"; } }
  leaf num-pkts { type uint32; }
}
3

Hello Joseph,
Can you please also suggest how to populate the values of these leaves from the C application? Usually, we define a callpoint under list construct in the yang. How would we do this in this specific scenario?

Regards.

4

you can have callpoint on the container too no problem.

quickest way is to just implement:

  • exists_optional() - existence check for container table node itself
  • get_elem() - pattern for leaves inside table as usually for any other leaves
    (dont’f take check existence of leaf into account too, as it may not be guaranteed that exists_optional() will be invoked by ConfD before get_elem on insider leaves…)

If you have get_object() et.c callbacks, i think same rules apply as for list entries, you just won’t have the key value in request input keypath… (so some sort of array of xml-begin table, table values, xml-end table, etc.)