Update json_v2 parser to handle null types (#9368)

(cherry picked from commit daec104)

Author: sspaink

plugins/parsers/json_v2/parser.go

@@ -306,31 +306,35 @@ func (p *Parser) expandArray(result MetricNode) ([]MetricNode, error) {
 			return nil, err
 		}
 	} else {
-		if !result.Tag && !result.IsObject() {
-			if result.SetName == p.currentSettings.TimestampKey {
-				if p.currentSettings.TimestampFormat == "" {
-					err := fmt.Errorf("use of 'timestamp_query' requires 'timestamp_format'")
-					return nil, err
-				}
-				timestamp, err := internal.ParseTimestamp(p.currentSettings.TimestampFormat, result.Value(), p.currentSettings.TimestampTimezone)
-				if err != nil {
-					return nil, err
+		if result.SetName == p.currentSettings.TimestampKey {
+			if p.currentSettings.TimestampFormat == "" {
+				err := fmt.Errorf("use of 'timestamp_query' requires 'timestamp_format'")
+				return nil, err
+			}
+			timestamp, err := internal.ParseTimestamp(p.currentSettings.TimestampFormat, result.Value(), p.currentSettings.TimestampTimezone)
+			if err != nil {
+				return nil, err
+			}
+			result.Metric.SetTime(timestamp)
+		} else {
+			switch result.Value().(type) {
+			case nil: // Ignore JSON values that are set as null
+			default:
+				if result.Tag {
+					result.DesiredType = "string"
 				}
-				result.Metric.SetTime(timestamp)
-			} else {
 				v, err := p.convertType(result.Value(), result.DesiredType, result.SetName)
 				if err != nil {
 					return nil, err
 				}
-				result.Metric.AddField(result.OutputName, v)
-			}
-		} else if !result.IsObject() {
-			v, err := p.convertType(result.Value(), "string", result.SetName)
-			if err != nil {
-				return nil, err
+				if result.Tag {
+					result.Metric.AddTag(result.OutputName, v.(string))
+				} else {
+					result.Metric.AddField(result.OutputName, v)
+				}
 			}
-			result.Metric.AddTag(result.OutputName, v.(string))
 		}
+
 		results = append(results, result)
 	}
 

plugins/parsers/json_v2/parser_test.go

@@ -69,6 +69,10 @@ func TestData(t *testing.T) {
 			name: "Test multiple timestamps",
 			test: "multiple_timestamps",
 		},
+		{
+			name: "Test field with null",
+			test: "null",
+		},
 	}
 
 	for _, tc := range tests {

plugins/parsers/json_v2/testdata/null/expected.out

@@ -0,0 +1 @@
+file,id=ak0217l8ue0x,type=Feature detail="https://earthquake.usgs.gov/earthquakes/feed/v1.0/detail/ak0217l8ue0x.geojson",mag=1.5,place="63 km N of Petersville, Alaska",status="automatic",time=1623708726566,updated=1623709998223,url="https://earthquake.usgs.gov/earthquakes/eventpage/ak0217l8ue0x"

plugins/parsers/json_v2/testdata/null/input.json

@@ -0,0 +1,40 @@
+{
+    "type": "FeatureCollection",
+    "metadata": {
+      "generated": 1623710450000,
+      "url": "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_hour.geojson",
+      "title": "USGS All Earthquakes, Past Hour",
+      "status": 200,
+      "api": "1.10.3",
+      "count": 10
+    },
+    "features": [
+      {
+        "type": "Feature",
+        "properties": {
+          "mag": 1.5,
+          "place": "63 km N of Petersville, Alaska",
+          "time": 1623708726566,
+          "updated": 1623709998223,
+          "tz": null,
+          "url": "https://earthquake.usgs.gov/earthquakes/eventpage/ak0217l8ue0x",
+          "detail": "https://earthquake.usgs.gov/earthquakes/feed/v1.0/detail/ak0217l8ue0x.geojson",
+          "felt": null,
+          "cdi": null,
+          "mmi": null,
+          "alert": null,
+          "status": "automatic"
+        },
+        "id": "ak0217l8ue0x"
+      }
+    ],
+    "bbox": [
+      -157.5749,
+      32.9001667,
+      0.25,
+      -115.6211667,
+      66.331,
+      132.5
+    ]
+  }
+  

plugins/parsers/json_v2/testdata/null/telegraf.conf

@@ -0,0 +1,8 @@
+[[inputs.file]]
+    files = ["./testdata/null/input.json"]
+    data_format = "json_v2"
+        [[inputs.file.json_v2]]
+            [[inputs.file.json_v2.object]]
+                path = "features"
+                tags = ["type", "id"]
+                disable_prepend_keys = true