feat/message-formatter-from-event

README.md

@@ -81,7 +81,7 @@ func main() {
         Str("Scale", "833 cents").
         Float64("Interval", 833.09).
         Msg("Fibonacci is everywhere")
-    
+
     log.Debug().
         Str("Name", "Tom").
         Send()
@@ -232,7 +232,7 @@ func main() {
 
 #### Error Logging with Stacktrace
 
-Using `github.com/pkg/errors`, you can add a formatted stacktrace to your errors. 
+Using `github.com/pkg/errors`, you can add a formatted stacktrace to your errors.
 
 ```go
 package main
@@ -352,6 +352,21 @@ output.FormatLevel = func(i interface{}) string {
 output.FormatMessage = func(i interface{}) string {
     return fmt.Sprintf("***%s****", i)
 }
+output.FormatMessageFromEvent = func(evt map[string]interface{}) zerolog.Formatter {
+    return func(i interface{}) string {
+        level := evt[zerolog.LevelFieldName]
+        switch level {
+        case zerolog.LevelInfoValue:
+            return fmt.Sprintf("=> %s %s", level, i)
+        case zerolog.LevelWarnValue:
+            return fmt.Sprintf("!! %s %s", level, i)
+        case zerolog.LevelErrorValue, zerolog.LevelFatalValue, zerolog.LevelPanicValue:
+            return fmt.Sprintf("XX %s %s", level, i)
+        default:
+            return fmt.Sprintf("%s", i)
+        }
+    }
+}
 output.FormatFieldName = func(i interface{}) string {
     return fmt.Sprintf("%s:", i)
 }
@@ -609,7 +624,7 @@ if err := http.ListenAndServe(":8080", nil); err != nil {
 ```
 
 ## Multiple Log Output
-`zerolog.MultiLevelWriter` may be used to send the log message to multiple outputs. 
+`zerolog.MultiLevelWriter` may be used to send the log message to multiple outputs.
 In this example, we send the log message to both `os.Stdout` and the in-built ConsoleWriter.
 ```go
 func main() {
@@ -640,7 +655,7 @@ Some settings can be changed and will be applied to all loggers:
 * `zerolog.ErrorFieldName`: Can be set to customize `Err` field name.
 * `zerolog.TimeFieldFormat`: Can be set to customize `Time` field value formatting. If set with `zerolog.TimeFormatUnix`, `zerolog.TimeFormatUnixMs` or `zerolog.TimeFormatUnixMicro`, times are formatted as UNIX timestamp.
 * `zerolog.DurationFieldUnit`: Can be set to customize the unit for time.Duration type fields added by `Dur` (default: `time.Millisecond`).
-* `zerolog.DurationFieldInteger`: If set to `true`, `Dur` fields are formatted as integers instead of floats (default: `false`). 
+* `zerolog.DurationFieldInteger`: If set to `true`, `Dur` fields are formatted as integers instead of floats (default: `false`).
 * `zerolog.ErrorHandler`: Called whenever zerolog fails to write an event on its output. If not set, an error is printed on the stderr. This handler must be thread safe and non-blocking.
 * `zerolog.FloatingPointPrecision`: If set to a value other than -1, controls the number
 of digits when formatting float numbers in JSON. See

console.go

@@ -47,6 +47,9 @@ const (
 // Formatter transforms the input into a formatted string.
 type Formatter func(interface{}) string
 
+// FormatterFromEvent generates a Formatter from an event.
+type FormatterFromEvent func(map[string]interface{}) Formatter
+
 // ConsoleWriter parses the JSON input and writes it in an
 // (optionally) colorized, human-friendly format to Out.
 type ConsoleWriter struct {
@@ -77,14 +80,15 @@ type ConsoleWriter struct {
 	// FieldsExclude defines contextual fields to not display in output.
 	FieldsExclude []string
 
-	FormatTimestamp     Formatter
-	FormatLevel         Formatter
-	FormatCaller        Formatter
-	FormatMessage       Formatter
-	FormatFieldName     Formatter
-	FormatFieldValue    Formatter
-	FormatErrFieldName  Formatter
-	FormatErrFieldValue Formatter
+	FormatTimestamp        Formatter
+	FormatLevel            Formatter
+	FormatCaller           Formatter
+	FormatMessage          Formatter
+	FormatMessageFromEvent FormatterFromEvent
+	FormatFieldName        Formatter
+	FormatFieldValue       Formatter
+	FormatErrFieldName     Formatter
+	FormatErrFieldValue    Formatter
 
 	FormatExtra func(map[string]interface{}, *bytes.Buffer) error
 
@@ -305,10 +309,12 @@ func (w ConsoleWriter) writePart(buf *bytes.Buffer, evt map[string]interface{},
 			f = w.FormatTimestamp
 		}
 	case MessageFieldName:
-		if w.FormatMessage == nil {
-			f = consoleDefaultFormatMessage(w.NoColor, evt[LevelFieldName])
-		} else {
+		if w.FormatMessageFromEvent != nil {
+			f = w.FormatMessageFromEvent(evt)
+		} else if w.FormatMessage != nil {
 			f = w.FormatMessage
+		} else {
+			f = consoleDefaultFormatMessage(w.NoColor, evt[LevelFieldName])
 		}
 	case CallerFieldName:
 		if w.FormatCaller == nil {

console_test.go

@@ -24,10 +24,22 @@ func ExampleConsoleWriter_customFormatters() {
 	out.FormatLevel = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("%-6s|", i)) }
 	out.FormatFieldName = func(i interface{}) string { return fmt.Sprintf("%s:", i) }
 	out.FormatFieldValue = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("%s", i)) }
+	out.FormatMessageFromEvent = func(evt map[string]interface{}) zerolog.Formatter {
+		return func(i interface{}) string {
+			level := evt[zerolog.LevelFieldName]
+			switch level {
+			case zerolog.LevelInfoValue, zerolog.LevelWarnValue, zerolog.LevelErrorValue, zerolog.LevelFatalValue, zerolog.LevelPanicValue:
+				return fmt.Sprintf("%s (%q formatted message)", i, level)
+			default:
+				return fmt.Sprintf("%s", i)
+			}
+		}
+	}
+
 	log := zerolog.New(out)
 
 	log.Info().Str("foo", "bar").Msg("Hello World")
-	// Output: <nil> INFO  | Hello World foo:BAR
+	// Output: <nil> INFO  | Hello World ("info" formatted message) foo:BAR
 }
 
 func ExampleNewConsoleWriter() {