Display only 60 items in graph

The decision is left to the template so template designers can easily change this behavior by removing the lastNItems filter in the template itself. Also the value can be changed easily.

fixes #4

filters/filter.go

@@ -0,0 +1,16 @@
+package filters
+
+import "github.com/flosch/pongo2"
+
+func init() {
+	pongo2.RegisterFilter("lastNItems", filterLastNItems)
+}
+
+func filterLastNItems(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, *pongo2.Error) {
+	if !in.CanSlice() {
+		return in, nil
+	}
+
+	from := in.Len() - param.Integer()
+	return in.Slice(from, in.Len()), nil
+}

main.go

@@ -13,6 +13,7 @@ import (
 	"github.com/flosch/pongo2"
 	"github.com/gorilla/mux"
 
+	_ "github.com/Luzifer/mondash/filters"
 	_ "github.com/flosch/pongo2-addons"
 )
 

structs.go

@@ -166,27 +166,21 @@ func (dm *dashboardMetric) StatisticalStatus() string {
 	return "OK"
 }
 
-func (dm *dashboardMetric) LabelHistory() string {
-	s := "["
-	for i, v := range dm.HistoricalData {
-		if i != 0 {
-			s = s + ", "
+func (dm *dashboardMetric) LabelHistory() []string {
+	s := []string{}
+	for _, v := range dm.HistoricalData[len(dm.HistoricalData)-60:] {
+		s = append(s, strconv.Itoa(int(v.Time.Unix())))
 	}
-		s = s + "" + strconv.Itoa(int(v.Time.Unix())) + ""
-	}
-	s = s + "]"
+
 	return s
 }
 
-func (dm *dashboardMetric) DataHistory() string {
-	s := "["
-	for i, v := range dm.HistoricalData {
-		if i != 0 {
-			s = s + ", "
+func (dm *dashboardMetric) DataHistory() []string {
+	s := []string{}
+	for _, v := range dm.HistoricalData[len(dm.HistoricalData)-60:] {
+		s = append(s, strconv.FormatFloat(v.Value, 'g', 4, 64))
 	}
-		s = s + strconv.FormatFloat(v.Value, 'g', 4, 64)
-	}
-	s = s + "]"
+
 	return s
 }
 

templates/dashboard.html

@@ -110,11 +110,9 @@
 			<script>
 				    var data = {
 				        // A labels array that can contain any sort of values
-				        labels: {{ metric.LabelHistory }},
+				        labels: [{{ metric.LabelHistory|lastNItems:"60"|join:"," }}],
 				        // Our series array that contains series objects or in this case series data arrays
-				        series: [
-				            {{ metric.DataHistory }}
-				        ]
+				        series: [[{{ metric.DataHistory|lastNItems:"60"|join:"," }}]]
 				    };
 
 					for (var i = 0; i < data.labels.length; i++) {