improve model1.Fields readability

internal/model1/fields.go

@@ -4,10 +4,7 @@
 package model1
 
 import (
-	"fmt"
 	"reflect"
-	"regexp"
-	"strings"
 )
 
 // Fields represents a collection of row fields.
@@ -16,34 +13,12 @@ type Fields []string
 // Customize returns a subset of fields.
 func (f Fields) Customize(cols []int, out Fields, extractionInfoBag ExtractionInfoBag) {
 	for i, c := range cols {
-		if c < 0 {
-
-			// If current index can retrieve an extractionInfo from extractionInfoBag,
-			// meaning this column has to retrieve the actual value from other field.
-			// For example: `LABELS[kubernetes.io/hostname]` needs to extract the value from column `LABELS`
-			if extractionInfo, ok := extractionInfoBag[i]; ok {
-				idxInFields := extractionInfo.IdxInFields
-				key := extractionInfo.Key
-
-				// Escape dots from the key
-				// For example: `kubernetes.io/hostname` needs to be escaped to `kubernetes\.io/hostname`
-				escapedKey := strings.ReplaceAll(key, ".", "\\.")
-
-				// Extract the value by using regex
-				pattern := fmt.Sprintf(`%s=([^ ]+)`, escapedKey)
-				regex := regexp.MustCompile(pattern)
 
-				// Find the value in the field that store original values
-				matches := regex.FindStringSubmatch(f[idxInFields])
-				if len(matches) > 1 {
-					out[i] = matches[1]
-					continue
-				}
-			}
-
-			out[i] = NAValue
+		if c < 0 {
+			out[i] = getValueOfInvalidColumn(f, i, extractionInfoBag)
 			continue
 		}
+
 		if c < len(f) {
 			out[i] = f[c]
 		}
@@ -68,3 +43,19 @@ func (f Fields) Clone() Fields {
 
 	return cp
 }
+
+func getValueOfInvalidColumn(f Fields, i int, extractionInfoBag ExtractionInfoBag) string {
+
+	extractionInfo, ok := extractionInfoBag[i]
+
+	// If the extractionInfo is existed in extractionInfoBag,
+	// meaning this column has to retrieve the actual value from other field.
+	// For example: `LABELS[kubernetes.io/hostname]` needs to extract the value from column `LABELS`
+	if ok {
+		idxInFields := extractionInfo.IdxInFields
+		escapedKey := escapeDots(extractionInfo.Key)
+		return extractValueFromField(escapedKey, f[idxInFields])
+	}
+
+	return NAValue
+}

internal/model1/helpers.go

@@ -6,6 +6,7 @@ package model1
 import (
 	"fmt"
 	"math"
+	"regexp"
 	"sort"
 	"strings"
 
@@ -164,3 +165,23 @@ func lessNumber(s1, s2 string) bool {
 
 	return sortorder.NaturalLess(v1, v2)
 }
+
+// Escape dots from the string
+// For example: `kubernetes.io/hostname` needs to be escaped to `kubernetes\.io/hostname`
+func escapeDots(s string) string {
+	return strings.ReplaceAll(s, ".", "\\.")
+}
+
+func extractValueFromField(key string, field string) string {
+	// Extract the value by using regex
+	pattern := fmt.Sprintf(`%s=([^ ]+)`, key)
+	regex := regexp.MustCompile(pattern)
+
+	// Find the value in the field that store original values
+	matches := regex.FindStringSubmatch(field)
+	if len(matches) > 1 {
+		return matches[1]
+	}
+
+	return ""
+}

internal/model1/helpers_test.go

@@ -87,3 +87,29 @@ func BenchmarkDurationToSecond(b *testing.B) {
 		durationToSeconds(t)
 	}
 }
+
+func TestEscapeDots(t *testing.T) {
+	var s string
+
+	s = escapeDots("kubernetes.io/hostname")
+	assert.Equal(t, "kubernetes\\.io/hostname", s)
+
+	s = escapeDots("kubernetes-io/hostname")
+	assert.Equal(t, "kubernetes-io/hostname", s)
+}
+
+func TestExtractValueFromFields(t *testing.T) {
+	k := escapeDots("kubernetes.io/hostname")
+	f := "kubernetes.io/arch=amd64 kubernetes.io/hostname=a-b-c-d kubernetes.io/os=linux"
+
+	var s string
+
+	s = extractValueFromField(k, f)
+	assert.Equal(t, "a-b-c-d", s)
+
+	s = extractValueFromField(k, "kubernetes.io/hostname=e-f-g-h "+f)
+	assert.Equal(t, "e-f-g-h", s)
+
+	s = extractValueFromField("random-key", f)
+	assert.Equal(t, "", s)
+}