Code to replace and delete single element in the list

YANG
1
  1. how to delete a single element in the list?
  2. how can we replace the element in the list if is already present in the list based on the order?
2
  1. config (config true) or operational state (config false) data?
  2. Application interfaces (e.g. MAAPI or CDB) or northbound interfaces, (e.g. NETCONF, RESTCONF, CLI, etc.)?
3

how config true will delete a element in the list, can you please share an example?

4

You didn’t answer the second question, but you did say “code” in the header for this topic. "code* and config true data would mean “MAAPI” to me, so based on the example in the RFC 7950:

  • 7.8.7. Usage Example (lists NETCONF)

Given the following list:

module example-config {
  yang-version 1.1;
  namespace "urn:example:config";
  prefix "co";

  revision 2020-06-14;
  
  list user {
    key "name";
    ordered-by user;
    description
      "This is a list of users in the system.";

    leaf name {
      type string;
    }
    leaf type {
      type string;
    }
    leaf full-name {
      type string;
    }
  }
}

With the following config:

  <config xmlns="http://tail-f.com/ns/config/1.0">
     <user xmlns="urn:example:config">
       <name>wilma</name>
       <type>admin</type>
       <full-name>Wilma Flintstone</full-name>
     </user>
     <user xmlns="urn:example:config">
       <name>barney</name>
       <type>admin</type>
       <full-name>Barney Rubble</full-name>
     </user>
     <user xmlns="urn:example:config">
       <name>fred</name>
       <type>admin</type>
       <full-name>Fred Flintstone</full-name>
     </user>
  </config>

To delete user "barney* using the MAAPI C-API:
maapi_delete(sock, tid, “/user{barney}”);

Using the confd_cmd tool that in turn use maapi_delete():

$ confd_cmd -dd -c 'mdel "/co:user{barney}"'
mdel "/co:user{barney}"
TRACE Connected (maapi) to ConfD
TRACE MAAPI_START_USER_SESSION  --> CONFD_OK
TRACE MAAPI_START_TRANS  --> CONFD_OK
TRACE MAAPI_DELETE /co:user{barney} --> CONFD_OK
TRACE MAAPI_APPLY_TRANS  --> CONFD_OK
TRACE MAAPI_STOP_TRANS  --> CONFD_OK
TRACE MAAPI_END_USER_SESSION  --> CONFD_OK

See $CONFD_DIIR/src/confd/tools/confd_cmd.c for source code

5

To insert a list entry you first create it using the MAAPI C-API maapi_create(), then set the “full-name” using maapi_set(), and lastly move the new entry after “wilma” using maapi_move_ordered()

Example using confd_cmd that use the above maapi functions:

$ confd_cmd -dd -c 'mcreate "/co:user{betty}"; mset /co:user{betty}/full-name "Betty Rubble"; mset /co:user{betty}/type admin; mmove "/co:user" "{betty}" after "wilma"'
mcreate "/co:user{betty}" ; mset "/co:user{betty}/full-name" "Betty Rubble" ; mset "/co:user{betty}/type" "admin" ; mmove "/co:user" "{betty}" "after" "wilma"
TRACE Connected (maapi) to ConfD
TRACE MAAPI_START_USER_SESSION  --> CONFD_OK
TRACE MAAPI_START_TRANS  --> CONFD_OK
TRACE MAAPI_CREATE /co:user{betty} --> CONFD_OK
TRACE MAAPI_SET_ELEM2 /co:user{betty}/full-name --> CONFD_OK
TRACE MAAPI_SET_ELEM2 /co:user{betty}/type --> CONFD_OK
TRACE Connected (maapi) to ConfD
TRACE MAAPI_LOAD_ALL_NS
TRACE MAAPI_LOAD_MNS_MAPS
TRACE MAAPI_LOAD_HASH_DB
TRACE MAAPI_MOVE_ORDERED /co:user{betty} --> CONFD_OK
TRACE MAAPI_APPLY_TRANS  --> CONFD_OK
TRACE MAAPI_STOP_TRANS  --> CONFD_OK
TRACE MAAPI_END_USER_SESSION  --> CONFD_OK

$ confd_load -dd -Fp -p /co:user 
TRACE Connected (maapi) to ConfD
starting user session ctxt=system user=system groups=[system]
TRACE MAAPI_START_USER_SESSION  --> CONFD_OK
TRACE MAAPI_START_TRANS  --> CONFD_OK
TRACE MAAPI_SAVE_CONFIG  --> CONFD_OK
TRACE Connected (stream) to ConfD
<config xmlns="http://tail-f.com/ns/config/1.0">
  <user xmlns="urn:example:config">
    <name>wilma</name>
    <type>admin</type>
    <full-name>Wilma Flintstone</full-name>
  </user>
  <user xmlns="urn:example:config">
    <name>betty</name>
    <type>admin</type>
    <full-name>Betty Rubble</full-name>
  </user>
  <user xmlns="urn:example:config">
    <name>fred</name>
    <type>admin</type>
    <full-name>Fred Flintstone</full-name>
  </user>
TRACE MAAPI_SAVE_CONFIG_RESULT  --> CONFD_OK
</config>
TRACE MAAPI_END_USER_SESSION  --> CONFD_OK