Errors when getting group name of a unit, leading to no stream kill events

[RobCollie]

The following is in our log:

2023-01-02 19:34:05.364 INFO Scripting (Main): event:type=kill,target_unit_type=BRDM-2,target_coalition=1,weapon=AGM-65L,t=5703.05,initiator_ws_type1=1,targetMissionID=1002613,initiator_unit_type=AV8BNA,target_ws_type1=2,initiator_object_id=16812805,initiator_coalition=2,target=BRDM-2,initiatorPilotName=TDCS | Pilot Pyles,initiatorMissionID=2166,target_object_id=17092097,
2023-01-02 19:34:05.364 ERROR SCRIPTING (Main): [GRPC] Error in event handler: [string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\exporters\object.lua"]:45: attempt to index a nil value
stack traceback:
[string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\exporters\object.lua"]:45: in function <[string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\exporters\object.lua"]:27>
(tail call): ?
[string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\methods\mission.lua"]:43: in function 'typed_exporter'
[string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\methods\mission.lua"]:341: in function <[string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\methods\mission.lua"]:63>
(tail call): ?
[C]: in function 'xpcall'
[string "C:\Users\TacticalDCS\Saved Games\instance2\Scripts\DCS-gRPC\grpc.lua"]:226: in function 'onEvent'
[string "Scripts/World/EventHandlers.lua"]:13: in function <[string "Scripts/World/EventHandlers.lua"]:11>

This links to this line in object.lua:

groupName = Unit.getGroup(unit):getName(),

[rurounijones]

Looks like ED broke something in the scripting... again. I will have a look at how to workaround this but please raise an issue on the ED forums and link it so we can track things their side as well.

[RobCollie]

https://forum.dcs.world/topic/314933-121622-patch-bug-dead-event-no-longer-includes-units-group-mission-breaking-issue/

This was actually already reported.

[soerenmeier]

Not sure if this is the correct fix but to get the kill events i applied following patch:

 lua/DCS-gRPC/exporters/object.lua | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lua/DCS-gRPC/exporters/object.lua b/lua/DCS-gRPC/exporters/object.lua
index cc791e4..422be8c 100644
--- a/lua/DCS-gRPC/exporters/object.lua
+++ b/lua/DCS-gRPC/exporters/object.lua
@@ -17,6 +17,11 @@ GRPC.exporters.position = function(pos)
 end
 
 GRPC.exporters.unit = function(unit)
+  local group = Unit.getGroup(unit)
+  if group then
+    group = GRPC.exporters.group(group)
+  end
+
   return {
     id = tonumber(unit:getID()),
     name = unit:getName(),
@@ -24,7 +29,7 @@ GRPC.exporters.unit = function(unit)
     coalition = unit:getCoalition() + 1, -- Increment for non zero-indexed gRPC enum
     type = unit:getTypeName(),
     playerName = Unit.getPlayerName(unit),
-    group = GRPC.exporters.group(Unit.getGroup(unit)),
+    group = group,
     numberInGroup = unit:getNumber(),
     rawTransform = GRPC.exporters.rawTransform(unit),
   }

Should a unit always have a group?

[rurounijones]

Yes units always have groups. This issue is due to ED changing things and making units not units anymore, but statics, probably as an attempt to optimise things.

Making group optional is going to be a right pain for clients. Grimes suggested that there is a very hacky workaround to this bug of getting the group by mangling the unit name to remove the unit specific information and onyl leave the group then use GetGroupByName. We may need to add that as a backup method if unit.group lua returns nil.

[rurounijones]

Clarified with Grimes and it appears that what needs to happen is that lua scripters need to create a lookup table for units to groups which is a right pain in the arse to do since we now have to manage unit state in parallel with DCS's own unit state and risk desync.

so we have two crappy options to choose from... thanks ED

[RobCollie]

sigh