Use multiple typed fields instead of single Info field of type interf…

…ace{}

nightscout.go

@@ -25,29 +25,37 @@ func (r Record) nightscoutEntry() nightscout.Entry {
 		DateString: t.Format(nightscout.DateStringLayout),
 		Device:     nightscout.Device(),
 	}
-	switch info := r.Info.(type) {
-	case SensorInfo:
+	if r.Sensor != nil {
+		info := r.Sensor
 		e.Type = nightscout.SGVType
 		e.Unfiltered = int(info.Unfiltered)
 		e.Filtered = int(info.Filtered)
 		e.RSSI = int(info.RSSI)
-	case EGVInfo:
+		return e
+	}
+	if r.EGV != nil {
+		info := r.EGV
 		e.Type = nightscout.SGVType
 		e.SGV = int(info.Glucose)
 		e.Direction = nightscoutTrend(info.Trend)
 		e.Noise = int(info.Noise)
-	case MeterInfo:
+		return e
+	}
+	if r.Meter != nil {
+		info := r.Meter
 		e.Type = nightscout.MBGType
 		e.MBG = int(info.Glucose)
-	case CalibrationInfo:
+		return e
+	}
+	if r.Calibration != nil {
+		info := r.Calibration
 		e.Type = nightscout.CalType
 		e.Slope = info.Slope
 		e.Intercept = info.Intercept
 		e.Scale = info.Scale
-	default:
-		panic(fmt.Sprintf("nightscoutEntry %+v", r))
+		return e
 	}
-	return e
+	panic(fmt.Sprintf("nightscoutEntry %+v", r))
 }
 
 func nightscoutTrend(t Trend) string {

nightscout_test.go

@@ -44,29 +44,29 @@ func nsDate(s string) int64 {
 var (
 	r1 = Record{
 		Timestamp: ts("2017-09-17T01:13:51-04:00"),
-		Info: CalibrationInfo{
+		Calibration: &CalibrationInfo{
 			Slope:     939.6817717490421,
 			Intercept: 35926.604186515906,
 			Scale:     1,
 		},
 	}
 	r2 = Record{
 		Timestamp: ts("2017-09-17T01:13:49-04:00"),
-		Info: MeterInfo{
+		Meter: &MeterInfo{
 			Glucose: 128,
 		},
 	}
 	r3 = Record{
 		Timestamp: ts("2017-09-17T11:13:17-04:00"),
-		Info: EGVInfo{
+		EGV: &EGVInfo{
 			Glucose: 84,
 			Trend:   Flat,
 			Noise:   1,
 		},
 	}
 	r4 = Record{
 		Timestamp: ts("2017-09-17T11:13:16-04:00"),
-		Info: SensorInfo{
+		Sensor: &SensorInfo{
 			Unfiltered: 119088,
 			Filtered:   110288,
 			RSSI:       -62,

record.go

@@ -9,8 +9,13 @@ import (
 type (
 	// Record represents a time-stamped Dexcom receiver record.
 	Record struct {
-		Timestamp Timestamp
-		Info      interface{}
+		Timestamp   Timestamp
+		XML         XMLInfo          `json:",omitempty"`
+		Sensor      *SensorInfo      `json:",omitempty"`
+		EGV         *EGVInfo         `json:",omitempty"`
+		Calibration *CalibrationInfo `json:",omitempty"`
+		Insertion   *InsertionInfo   `json:",omitempty"`
+		Meter       *MeterInfo       `json:",omitempty"`
 	}
 
 	// Records represents a sequence of records.
@@ -69,7 +74,7 @@ func (r Record) Time() time.Time {
 
 // Glucose returns the glucose field from an EGV record.
 func (r Record) Glucose() uint16 {
-	return r.Info.(EGVInfo).Glucose
+	return r.EGV.Glucose
 }
 
 // Len returns the number of records.
@@ -104,7 +109,7 @@ func (r *Record) unmarshal(pageType PageType, v []byte) error {
 }
 
 func unmarshalSensorInfo(r *Record, v []byte) {
-	r.Info = SensorInfo{
+	r.Sensor = &SensorInfo{
 		Unfiltered: unmarshalUint32(v[8:12]),
 		Filtered:   unmarshalUint32(v[12:16]),
 		RSSI:       int8(v[16]),
@@ -181,7 +186,7 @@ const (
 
 func umarshalEGVInfo(r *Record, v []byte) {
 	g := unmarshalUint16(v[8:10])
-	r.Info = EGVInfo{
+	r.EGV = &EGVInfo{
 		Glucose:     g & EGVValueMask,
 		DisplayOnly: g&EGVDisplayOnly != 0,
 		Noise:       v[10] & EGVNoiseMask >> 4,
@@ -190,7 +195,7 @@ func umarshalEGVInfo(r *Record, v []byte) {
 }
 
 func unmarshalCalibrationInfo(r *Record, v []byte) {
-	cal := CalibrationInfo{
+	cal := &CalibrationInfo{
 		Slope:     unmarshalFloat64(v[8:16]),
 		Intercept: unmarshalFloat64(v[16:24]),
 		Scale:     unmarshalFloat64(v[24:32]),
@@ -206,7 +211,7 @@ func unmarshalCalibrationInfo(r *Record, v []byte) {
 		cal.Data[i].TimeApplied = cal.Data[i].TimeApplied.Add(offset)
 		v = v[17:]
 	}
-	r.Info = cal
+	r.Calibration = cal
 }
 
 func (r *CalibrationRecord) unmarshal(v []byte) {
@@ -237,14 +242,14 @@ func unmarshalInsertionInfo(r *Record, v []byte) {
 	if !bytes.Equal(u, invalidTime) {
 		t = unmarshalTime(u)
 	}
-	r.Info = InsertionInfo{
+	r.Insertion = &InsertionInfo{
 		SystemTime: t,
 		Event:      SensorChange(v[12]),
 	}
 }
 
 func unmarshalMeterInfo(r *Record, v []byte) {
-	r.Info = MeterInfo{
+	r.Meter = &MeterInfo{
 		Glucose:   unmarshalUint16(v[8:10]),
 		MeterTime: unmarshalTime(v[10:14]),
 	}

xml.go

@@ -16,7 +16,7 @@ func umarshalXMLInfo(r *Record, v []byte) {
 	if i != -1 {
 		v = v[:i]
 	}
-	r.Info = umarshalXMLBytes(v)
+	r.XML = umarshalXMLBytes(v)
 }
 
 func umarshalXMLBytes(v []byte) XMLInfo {