From 1d7177fb26596e412439f9163dc15de0335c8de3 Mon Sep 17 00:00:00 2001
From: Martin Riedl <martin.riedl.92@googlemail.com>
Date: Wed, 5 Mar 2025 17:48:47 +0100
Subject: [PATCH] feat: new priority key settings for key value formatter

---
 cmd/keyValueFormatter/main.go | 30 ++++++++++++++++++++++++++++++
 formatter_keyvalue.go         | 26 ++++++++++++++++++++++++--
 2 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 cmd/keyValueFormatter/main.go

diff --git a/cmd/keyValueFormatter/main.go b/cmd/keyValueFormatter/main.go
new file mode 100644
index 0000000..9e1424a
--- /dev/null
+++ b/cmd/keyValueFormatter/main.go
@@ -0,0 +1,30 @@
+package main
+
+import (
+	"time"
+
+	"git.martin-riedl.de/golang/log"
+)
+
+func main() {
+	advancedSettings()
+}
+
+func advancedSettings() {
+	// Key Value Formatter with special settings
+	formatter := log.NewFormatterKeyValue()
+	formatter.HighPriorityKeys = []string{"firstField"}
+	formatter.PriorityKeys = []string{"secondField"}
+	formatter.TimeFormat = time.RFC3339Nano
+
+	// create new log instance
+	output := log.NewOutput(log.LevelDebug, formatter, log.NewPrinterStdout())
+	logger := log.NewLogger([]*log.Output{output})
+
+	// log some message
+	logger.WithMap(log.Map{
+		"someField":   "Martin",
+		"firstField":  "John",
+		"secondField": "Doe",
+	}).Info("This is an info message")
+}
diff --git a/formatter_keyvalue.go b/formatter_keyvalue.go
index e8da5d2..74ac8ab 100644
--- a/formatter_keyvalue.go
+++ b/formatter_keyvalue.go
@@ -16,12 +16,17 @@ package log
 
 import (
 	"fmt"
+	"slices"
 	"strings"
 	"time"
 )
 
 type FormatterKeyValue struct {
-	TimeFormat       string
+	TimeFormat string
+	// HighPriorityKeys are printed before the actual log message
+	HighPriorityKeys []string
+	// PriorityKeys are printed after the log message
+	PriorityKeys     []string
 	builder          strings.Builder
 	isFirstKVWritten bool
 }
@@ -45,9 +50,23 @@ func (formatter *FormatterKeyValue) Begin(entry *Entry) {
 }
 
 func (formatter *FormatterKeyValue) Process(entry *Entry) {
+	// log high priority keys
+	for _, content := range entry.Content {
+		if slices.Contains(formatter.HighPriorityKeys, content.Key) {
+			formatter.addKV(content.Key, content.Value)
+		}
+	}
+
 	// add message
 	formatter.addKV("message", entry.Message)
 
+	// log priority keys
+	for _, content := range entry.Content {
+		if slices.Contains(formatter.PriorityKeys, content.Key) {
+			formatter.addKV(content.Key, content.Value)
+		}
+	}
+
 	// add call stack
 	if len(entry.CallStack) > 0 {
 		caller := entry.CallStack[0]
@@ -57,7 +76,10 @@ func (formatter *FormatterKeyValue) Process(entry *Entry) {
 
 	// add additional fields
 	for _, content := range entry.Content {
-		formatter.addKV(content.Key, content.Value)
+		if !slices.Contains(formatter.HighPriorityKeys, content.Key) &&
+			!slices.Contains(formatter.PriorityKeys, content.Key) {
+			formatter.addKV(content.Key, content.Value)
+		}
 	}
 }