Merge pull request #677 from neilisaac/text-field-map

Add FieldMap support to TextFormatter

formatter.go

@@ -34,15 +34,18 @@ func prefixFieldClashes(data Fields, fieldMap FieldMap) {
 	timeKey := fieldMap.resolve(FieldKeyTime)
 	if t, ok := data[timeKey]; ok {
 		data["fields."+timeKey] = t
+		delete(data, timeKey)
 	}
 
 	msgKey := fieldMap.resolve(FieldKeyMsg)
 	if m, ok := data[msgKey]; ok {
 		data["fields."+msgKey] = m
+		delete(data, msgKey)
 	}
 
 	levelKey := fieldMap.resolve(FieldKeyLevel)
 	if l, ok := data[levelKey]; ok {
 		data["fields."+levelKey] = l
+		delete(data, levelKey)
 	}
 }

text_formatter.go

@@ -51,7 +51,6 @@ type TextFormatter struct {
 	// be desired.
 	DisableSorting bool
 
-
 	// Disables the truncation of the level text to 4 characters.
 	DisableLevelTruncation bool
 
@@ -61,6 +60,15 @@ type TextFormatter struct {
 	// Whether the logger's out is to a terminal
 	isTerminal bool
 
+	// FieldMap allows users to customize the names of keys for default fields.
+	// As an example:
+	// formatter := &TextFormatter{
+	//     FieldMap: FieldMap{
+	//         FieldKeyTime:  "@timestamp",
+	//         FieldKeyLevel: "@level",
+	//         FieldKeyMsg:   "@message"}}
+	FieldMap FieldMap
+
 	sync.Once
 }
 
@@ -72,7 +80,8 @@ func (f *TextFormatter) init(entry *Entry) {
 
 // Format renders a single log entry
 func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
-	var b *bytes.Buffer
+	prefixFieldClashes(entry.Data, f.FieldMap)
+
 	keys := make([]string, 0, len(entry.Data))
 	for k := range entry.Data {
 		keys = append(keys, k)
@@ -81,14 +90,14 @@ func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
 	if !f.DisableSorting {
 		sort.Strings(keys)
 	}
+
+	var b *bytes.Buffer
 	if entry.Buffer != nil {
 		b = entry.Buffer
 	} else {
 		b = &bytes.Buffer{}
 	}
 
-	prefixFieldClashes(entry.Data, emptyFieldMap)
-
 	f.Do(func() { f.init(entry) })
 
 	isColored := (f.ForceColors || f.isTerminal) && !f.DisableColors
@@ -101,11 +110,11 @@ func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
 		f.printColored(b, entry, keys, timestampFormat)
 	} else {
 		if !f.DisableTimestamp {
-			f.appendKeyValue(b, "time", entry.Time.Format(timestampFormat))
+			f.appendKeyValue(b, f.FieldMap.resolve(FieldKeyTime), entry.Time.Format(timestampFormat))
 		}
-		f.appendKeyValue(b, "level", entry.Level.String())
+		f.appendKeyValue(b, f.FieldMap.resolve(FieldKeyLevel), entry.Level.String())
 		if entry.Message != "" {
-			f.appendKeyValue(b, "msg", entry.Message)
+			f.appendKeyValue(b, f.FieldMap.resolve(FieldKeyMsg), entry.Message)
 		}
 		for _, key := range keys {
 			f.appendKeyValue(b, key, entry.Data[key])

text_formatter_test.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestFormatting(t *testing.T) {
@@ -175,5 +177,44 @@ func TestDisableTimestampWithColoredOutput(t *testing.T) {
 	}
 }
 
+func TestTextFormatterFieldMap(t *testing.T) {
+	formatter := &TextFormatter{
+		DisableColors: true,
+		FieldMap: FieldMap{
+			FieldKeyMsg:   "message",
+			FieldKeyLevel: "somelevel",
+			FieldKeyTime:  "timeywimey",
+		},
+	}
+
+	entry := &Entry{
+		Message: "oh hi",
+		Level:   WarnLevel,
+		Time:    time.Date(1981, time.February, 24, 4, 28, 3, 100, time.UTC),
+		Data: Fields{
+			"field1":     "f1",
+			"message":    "messagefield",
+			"somelevel":  "levelfield",
+			"timeywimey": "timeywimeyfield",
+		},
+	}
+
+	b, err := formatter.Format(entry)
+	if err != nil {
+		t.Fatal("Unable to format entry: ", err)
+	}
+
+	assert.Equal(t,
+		`timeywimey="1981-02-24T04:28:03Z" `+
+			`somelevel=warning `+
+			`message="oh hi" `+
+			`field1=f1 `+
+			`fields.message=messagefield `+
+			`fields.somelevel=levelfield `+
+			`fields.timeywimey=timeywimeyfield`+"\n",
+		string(b),
+		"Formatted output doesn't respect FieldMap")
+}
+
 // TODO add tests for sorting etc., this requires a parser for the text
 // formatter output.