InfluxDB: Fix type assertion panics for interface conversion: interface {} is nil (#64556)

* fix type assertions

* fix chk

* add nil and fix tests

* add test for null bool and strings in the JSON response to be parsed as nil in Go

* reduce complexity

* reduce complexity

* reduce complexity again

* switch case for valTypes

pkg/tsdb/influxdb/response_parser.go

@@ -23,6 +23,7 @@ func (rp *ResponseParser) Parse(buf io.ReadCloser, queries []Query) *backend.Que
 	resp := backend.NewQueryDataResponse()
 
 	response, jsonErr := parseJSON(buf)
+
 	if jsonErr != nil {
 		resp.Responses["A"] = backend.DataResponse{Error: jsonErr}
 		return resp
@@ -46,10 +47,12 @@ func (rp *ResponseParser) Parse(buf io.ReadCloser, queries []Query) *backend.Que
 
 func parseJSON(buf io.ReadCloser) (Response, error) {
 	var response Response
+
 	dec := json.NewDecoder(buf)
 	dec.UseNumber()
 
 	err := dec.Decode(&response)
+
 	return response, err
 }
 
@@ -89,8 +92,8 @@ func transformRows(rows []Row, query Query) data.Frames {
 
 				var timeArray []time.Time
 				var floatArray []*float64
-				var stringArray []string
-				var boolArray []bool
+				var stringArray []*string
+				var boolArray []*bool
 				valType := typeof(row.Values, colIndex)
 				name := formatFrameName(row, column, query)
 
@@ -99,16 +102,27 @@ func transformRows(rows []Row, query Query) data.Frames {
 					// we only add this row if the timestamp is valid
 					if timestampErr == nil {
 						timeArray = append(timeArray, timestamp)
-						if valType == "string" {
-							value := valuePair[colIndex].(string)
-							stringArray = append(stringArray, value)
-						} else if valType == "json.Number" {
+						switch valType {
+						case "string":
+							{
+								value, chk := valuePair[colIndex].(string)
+								if chk {
+									stringArray = append(stringArray, &value)
+								} else {
+									stringArray = append(stringArray, nil)
+								}
+							}
+						case "json.Number":
 							value := parseNumber(valuePair[colIndex])
 							floatArray = append(floatArray, value)
-						} else if valType == "bool" {
-							value := valuePair[colIndex].(bool)
-							boolArray = append(boolArray, value)
-						} else if valType == "null" {
+						case "bool":
+							value, chk := valuePair[colIndex].(bool)
+							if chk {
+								boolArray = append(boolArray, &value)
+							} else {
+								boolArray = append(boolArray, nil)
+							}
+						case "null":
 							floatArray = append(floatArray, nil)
 						}
 					}

pkg/tsdb/influxdb/response_parser_test.go

@@ -41,7 +41,7 @@ func TestInfluxdbResponseParser(t *testing.T) {
 		require.Error(t, result.Responses["A"].Error)
 	})
 
-	t.Run("Influxdb response parser should parse everything normally", func(t *testing.T) {
+	t.Run("Influxdb response parser should parse everything normally including nil bools and nil strings", func(t *testing.T) {
 		parser := &ResponseParser{}
 
 		response := `
@@ -54,7 +54,7 @@ func TestInfluxdbResponseParser(t *testing.T) {
 							"columns": ["time","mean","path","isActive"],
 							"tags": {"datacenter": "America"},
 							"values": [
-								[111,222,"/usr/path",true],
+								[111,222,null,null],
 								[111,222,"/usr/path",false],
 								[111,null,"/usr/path",true]
 							]
@@ -84,8 +84,9 @@ func TestInfluxdbResponseParser(t *testing.T) {
 		)
 		floatFrame.Meta = &data.FrameMeta{ExecutedQueryString: "Test raw query"}
 
-		stringField := data.NewField("value", labels, []string{
-			"/usr/path", "/usr/path", "/usr/path",
+		string_test := "/usr/path"
+		stringField := data.NewField("value", labels, []*string{
+			nil, &string_test, &string_test,
 		})
 		stringField.Config = &data.FieldConfig{DisplayNameFromDS: "cpu.path { datacenter: America }"}
 		stringFrame := data.NewFrame("cpu.path { datacenter: America }",
@@ -99,8 +100,10 @@ func TestInfluxdbResponseParser(t *testing.T) {
 		)
 		stringFrame.Meta = &data.FrameMeta{ExecutedQueryString: "Test raw query"}
 
-		boolField := data.NewField("value", labels, []bool{
-			true, false, true,
+		bool_true := true
+		bool_false := false
+		boolField := data.NewField("value", labels, []*bool{
+			nil, &bool_false, &bool_true,
 		})
 		boolField.Config = &data.FieldConfig{DisplayNameFromDS: "cpu.isActive { datacenter: America }"}
 		boolFrame := data.NewFrame("cpu.isActive { datacenter: America }",