From ef7681f68970fc800b78ce127a732252ec6b7847 Mon Sep 17 00:00:00 2001
From: Alexander Zobnin <alexanderzobnin@gmail.com>
Date: Thu, 27 May 2021 16:47:18 +0300
Subject: [PATCH] Implement transformNull

---
 pkg/datasource/functions.go           | 21 ++++++++++++++++-----
 pkg/timeseries/transform_functions.go | 13 +++++++++++++
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/pkg/datasource/functions.go b/pkg/datasource/functions.go
index 6e00539..2af7a98 100644
--- a/pkg/datasource/functions.go
+++ b/pkg/datasource/functions.go
@@ -57,11 +57,12 @@ var frontendFuncMap map[string]bool
 
 func init() {
 	seriesFuncMap = map[string]DataProcessingFunc{
-		"groupBy":    applyGroupBy,
-		"scale":      applyScale,
-		"offset":     applyOffset,
-		"percentile": applyPercentile,
-		"timeShift":  applyTimeShiftPost,
+		"groupBy":       applyGroupBy,
+		"scale":         applyScale,
+		"offset":        applyOffset,
+		"transformNull": applyTransformNull,
+		"percentile":    applyPercentile,
+		"timeShift":     applyTimeShiftPost,
 	}
 
 	aggFuncMap = map[string]AggDataProcessingFunc{
@@ -202,6 +203,16 @@ func applyOffset(series timeseries.TimeSeries, params ...interface{}) (timeserie
 	return series.Transform(transformFunc), nil
 }
 
+func applyTransformNull(series timeseries.TimeSeries, params ...interface{}) (timeseries.TimeSeries, error) {
+	nullValue, err := MustFloat64(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
+	transformFunc := timeseries.TransformNull(nullValue)
+	return series.Transform(transformFunc), nil
+}
+
 func applyAggregateBy(series []*timeseries.TimeSeriesData, params ...interface{}) ([]*timeseries.TimeSeriesData, error) {
 	pInterval, err := MustString(params[0])
 	pAgg, err := MustString(params[1])
diff --git a/pkg/timeseries/transform_functions.go b/pkg/timeseries/transform_functions.go
index d989b95..f7c0eb6 100644
--- a/pkg/timeseries/transform_functions.go
+++ b/pkg/timeseries/transform_functions.go
@@ -14,6 +14,12 @@ func TransformOffset(offset float64) TransformFunc {
 	}
 }
 
+func TransformNull(nullValue float64) TransformFunc {
+	return func(point TimePoint) TimePoint {
+		return transformNull(point, nullValue)
+	}
+}
+
 func TransformShiftTime(interval time.Duration) TransformFunc {
 	return func(point TimePoint) TimePoint {
 		return transformShiftTime(point, interval)
@@ -41,3 +47,10 @@ func transformShiftTime(point TimePoint, interval time.Duration) TimePoint {
 	point.Time = shiftedTime
 	return point
 }
+
+func transformNull(point TimePoint, nullValue float64) TimePoint {
+	if point.Value == nil {
+		point.Value = &nullValue
+	}
+	return point
+}