fix(parsers.xpath): Fix panic for JSON name expansion (#12724)

plugins/parsers/xpath/json_document.go

@@ -44,7 +44,12 @@ func (d *jsonDocument) GetNodePath(node, relativeTo dataNode, sep string) string
 	// Climb up the tree and collect the node names
 	n := nativeNode.Parent
 	for n != nil && n != nativeRelativeTo {
-		switch reflect.TypeOf(n.Parent.Value()).Kind() {
+		kind := reflect.Invalid
+		if n.Parent != nil && n.Parent.Value() != nil {
+			kind = reflect.TypeOf(n.Parent.Value()).Kind()
+		}
+
+		switch kind {
 		case reflect.Slice, reflect.Array:
 			// Determine the index for array elements
 			names = append(names, d.index(n))

plugins/parsers/xpath/testcases/json_array_expand/expected.out

@@ -0,0 +1 @@
+foo adr=true,applicationID="1",applicationName="Test",data="AGhCAGcA0g==",devEUI="27c0817d2aba3052",deviceName="TcsSensorNode",deviceProfileID="100ca98d-e075-4b1b-8cd3-41edbab355f5",deviceProfileName="TcsSensor",fCnt=71,fPort=2,object_humiditySensor_0=33,object_humiditySensor_1=25.5,object_temperatureSensor_0=21,object_temperatureSensor_1=19.3,rxInfo_0_gatewayID="b827ebfffeaa4582",rxInfo_0_loRaSNR=7.5,rxInfo_0_name="local",rxInfo_0_rssi=-60,rxInfo_0_uplinkID="659cbfab-3216-42fd-9f71-f2c470b7f9da",rxInfo_1_gatewayID="ca925641ce08b33e",rxInfo_1_loRaSNR=4.2,rxInfo_1_name="local",rxInfo_1_rssi=-98,rxInfo_1_uplinkID="15ca3b44-17a0-4662-82c9-aa23b40e16eb",txInfo_dr=5,txInfo_frequency=868500000,timestamp=1677099936000000000 1677099936000000000

plugins/parsers/xpath/testcases/json_array_expand/telegraf.conf

@@ -0,0 +1,12 @@
+[[inputs.file]]
+  files = ["./testcases/json_array_expand/test.json"]
+  data_format = "xpath_json"
+
+  xpath_native_types = true
+
+  [[inputs.file.xpath]]
+    field_name_expansion = true
+    metric_name = "'foo'"
+    field_selection = "descendant::*"
+    timestamp = "//timestamp"
+    timestamp_format = "unix_ns"

plugins/parsers/xpath/testcases/json_array_expand/test.json

@@ -0,0 +1,43 @@
+{
+  "applicationID":"1",
+  "applicationName":"Test",
+  "deviceName":"TcsSensorNode",
+  "deviceProfileName":"TcsSensor",
+  "deviceProfileID":"100ca98d-e075-4b1b-8cd3-41edbab355f5",
+  "devEUI":"27c0817d2aba3052",
+  "timestamp": 1677099936000000000,
+  "rxInfo":[
+     {
+        "gatewayID":"b827ebfffeaa4582",
+        "uplinkID":"659cbfab-3216-42fd-9f71-f2c470b7f9da",
+        "name":"local",
+        "rssi":-60,
+        "loRaSNR":7.5
+     },
+     {
+        "gatewayID":"ca925641ce08b33e",
+        "uplinkID":"15ca3b44-17a0-4662-82c9-aa23b40e16eb",
+        "name":"local",
+        "rssi":-98,
+        "loRaSNR":4.2
+     }
+  ],
+  "txInfo":{
+     "frequency":868500000,
+     "dr":5
+  },
+  "adr":true,
+  "fCnt":71,
+  "fPort":2,
+  "data":"AGhCAGcA0g==",
+  "object":{
+     "humiditySensor":{
+        "0":33,
+        "1":25.5
+     },
+     "temperatureSensor":{
+        "0":21,
+        "1":19.3
+     }
+  }
+}