Fix for dhcp_relay deletion on a VLAN (sonic-net#813)

Signed-off-by: Akhilesh Samineni <akhilesh.samineni@broadcom.com>

config/main.py

@@ -1193,7 +1193,8 @@ def add_vlan_dhcp_relay_destination(ctx, vid, dhcp_relay_destination_ip):
  return
  else:
  dhcp_relay_dests.append(dhcp_relay_destination_ip)
- db.set_entry('VLAN', vlan_name, {"dhcp_servers":dhcp_relay_dests})
+ vlan['dhcp_servers'] = dhcp_relay_dests
+ db.set_entry('VLAN', vlan_name, vlan)
  click.echo("Added DHCP relay destination address {} to {}".format(dhcp_relay_destination_ip, vlan_name))
  try:
  click.echo("Restarting DHCP relay service...")
@@ -1218,7 +1219,11 @@ def del_vlan_dhcp_relay_destination(ctx, vid, dhcp_relay_destination_ip):
  dhcp_relay_dests = vlan.get('dhcp_servers', [])
  if dhcp_relay_destination_ip in dhcp_relay_dests:
  dhcp_relay_dests.remove(dhcp_relay_destination_ip)
- db.set_entry('VLAN', vlan_name, {"dhcp_servers":dhcp_relay_dests})
+ if len(dhcp_relay_dests) == 0:
+ del vlan['dhcp_servers']
+ else:
+ vlan['dhcp_servers'] = dhcp_relay_dests
+ db.set_entry('VLAN', vlan_name, vlan)
  click.echo("Removed DHCP relay destination address {} from {}".format(dhcp_relay_destination_ip, vlan_name))
  try:
  click.echo("Restarting DHCP relay service...")