From 0f38511ea8303b42007b5bdf7b85ebd6fafc833f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miguel=20Mart=C3=ADnez=20Trivi=C3=B1o?=
 <migmartri@gmail.com>
Date: Mon, 7 Nov 2022 07:24:41 +0100
Subject: [PATCH] fix(filter): filter out keyvals if keyFunc is provided
 (#2484)

---
 log/filter.go      | 16 +++++++---------
 log/filter_test.go | 13 +++++++++++--
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/log/filter.go b/log/filter.go
index ab5723770..993fa926e 100644
--- a/log/filter.go
+++ b/log/filter.go
@@ -64,20 +64,18 @@ func (f *Filter) Log(level Level, keyvals ...interface{}) error {
 	if level < f.level {
 		return nil
 	}
-	// fkv is used to provide a slice to contains both logger.prefix and keyvals for filter
-	var fkv []interface{}
+	// prefixkv contains the slice of arguments defined as prefixes during the log initialization
+	var prefixkv []interface{}
 	l, ok := f.logger.(*logger)
 	if ok && len(l.prefix) > 0 {
-		fkv = make([]interface{}, 0, len(l.prefix)+len(keyvals))
-		fkv = append(fkv, l.prefix...)
-		fkv = append(fkv, keyvals...)
+		prefixkv = make([]interface{}, 0, len(l.prefix))
+		prefixkv = append(prefixkv, l.prefix...)
 	}
-	if !ok {
-		fkv = keyvals
-	}
-	if f.filter != nil && f.filter(level, fkv...) {
+
+	if f.filter != nil && (f.filter(level, prefixkv...) || f.filter(level, keyvals...)) {
 		return nil
 	}
+
 	if len(f.key) > 0 || len(f.value) > 0 {
 		for i := 0; i < len(keyvals); i += 2 {
 			v := i + 1
diff --git a/log/filter_test.go b/log/filter_test.go
index d3c8d5485..3e36deac1 100644
--- a/log/filter_test.go
+++ b/log/filter_test.go
@@ -102,13 +102,19 @@ func TestFilterFuncWitchLoggerPrefix(t *testing.T) {
 			want:   "",
 		},
 		{
+			// Filtered value
 			logger: NewFilter(With(NewStdLogger(buf), "caller", "caller"), FilterFunc(testFilterFuncWithLoggerPrefix)),
-			want:   "INFO caller=caller msg=msg\n",
+			want:   "INFO caller=caller msg=msg filtered=***\n",
+		},
+		{
+			// NO prefix
+			logger: NewFilter(With(NewStdLogger(buf)), FilterFunc(testFilterFuncWithLoggerPrefix)),
+			want:   "INFO msg=msg filtered=***\n",
 		},
 	}
 
 	for _, tt := range tests {
-		err := tt.logger.Log(LevelInfo, "msg", "msg")
+		err := tt.logger.Log(LevelInfo, "msg", "msg", "filtered", "true")
 		if err != nil {
 			t.Fatal("err should be nil")
 		}
@@ -128,6 +134,9 @@ func testFilterFuncWithLoggerPrefix(level Level, keyvals ...interface{}) bool {
 		if keyvals[i] == "prefix" {
 			return true
 		}
+		if keyvals[i] == "filtered" {
+			keyvals[i+1] = fuzzyStr
+		}
 	}
 	return false
 }