Kuiper may panic when sendSingle is set to true but without specifying dataTemplate

[novuscy]

here is the rule I created:

{
  "sql": "SELECT DynamicInfo from edgex_stream",
  "actions": [
    {
      "mqtt": {
        "server": "tcp://localhost:1883",
        "topic": "rules_test",
        "sendSingle": true
      }
    },
    {
      "log":{}
    }
  ]
}

here is the panic log:

time="2020-08-12T14:57:12+08:00" level=debug msg="receive 1 records" file="entry.go:314" rule=rule2
time="2020-08-12T14:57:12+08:00" level=debug msg=success file="entry.go:314" rule=rule2
time="2020-08-12T14:57:12+08:00" level=debug msg="broadcast from project to mqtt_0 done" file="entry.go:314" rule=rule2
time="2020-08-12T14:57:12+08:00" level=debug msg="broadcast from project to log_1 done" file="entry.go:314" rule=rule2
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x459805b]

goroutine 263 [running]:
text/template.errRecover(0xc000483c60)
	/usr/local/Cellar/go/1.14.3/libexec/src/text/template/exec.go:163 +0x1c2
panic(0x46ce420, 0x4d3c6d0)
	/usr/local/Cellar/go/1.14.3/libexec/src/runtime/panic.go:969 +0x166
text/template.(*Template).execute(0x0, 0x487ce60, 0xc0001f8570, 0x46c9440, 0xc0001f8540, 0x0, 0x0)
	/usr/local/Cellar/go/1.14.3/libexec/src/text/template/exec.go:217 +0x19b
text/template.(*Template).Execute(...)
	/usr/local/Cellar/go/1.14.3/libexec/src/text/template/exec.go:203
github.com/emqx/kuiper/xstream/nodes.doCollect(0x488f140, 0xc000138d20, 0xc0001fe4a0, 0x4893b00, 0xc00052c990, 0x3e8, 0xc0000a0100, 0x0, 0xc00053e3c0, 0x4898740, ...)
	/Users/novuscy/Projects/edgex/kuiper/xstream/nodes/sink_node.go:274 +0x5da
github.com/emqx/kuiper/xstream/nodes.(*SinkNode).Open.func1.1(0xc000519380, 0xc00032a360, 0x4898740, 0xc0001f44d0, 0x4897340, 0xc0001f4380, 0xc00002b428, 0xc00002b430, 0xc00002b418, 0xc00002b420, ...)
	/Users/novuscy/Projects/edgex/kuiper/xstream/nodes/sink_node.go:204 +0x4cc
created by github.com/emqx/kuiper/xstream/nodes.(*SinkNode).Open.func1
	/Users/novuscy/Projects/edgex/kuiper/xstream/nodes/sink_node.go:158 +0x620

I think some boundary check is needed, or maybe just ignore the sendSingle value when dataTemplate is not specified?

[jinfahua]

@novuscy thanks for your report, we'll investigate see if it's necessary to add validation against the settings.

[jinfahua]

Fixed & close the issue.