coder · ammario · May 16, 2023
diff --git a/internal/entryhuman/entry.go b/internal/entryhuman/entry.go
@@ -64,6 +64,13 @@ func formatValue(v interface{}) string {
 			return fmt.Sprintf("error calling Value: %v", err)
 		}
 	}
+	if _, ok := v.(slog.Map); ok {
+		byt, err := json.Marshal(v)
+		if err != nil {
+			panic(err)
+		}
+		return string(byt)
+	}
 	if v == nil {
 		return "<nil>"
 	}

diff --git a/internal/entryhuman/testdata/object.golden b/internal/entryhuman/testdata/object.golden
@@ -1 +1 @@
-0001-01-01 00:00:00.000 [warn]    obj="[{Name:obj1 Value:{foo:1 bar:2 dra:[98 108 97 104]}} {Name:obj2 Value:{foo:3 bar:4 dra:[98 108 97 104]}}]"  map={"key1":"value1"}
+0001-01-01 00:00:00.000 [warn]    obj={"obj1":"{foo:1 bar:2 dra:[98 108 97 104]}","obj2":"{foo:3 bar:4 dra:[98 108 97 104]}"}  map={"key1":"value1"}
diff --git a/slog.go b/slog.go
@@ -40,7 +40,14 @@ func (l Logger) Log(ctx context.Context, e SinkEntry) {
 		return
 	}
 
-	e.Fields = l.fields.append(e.Fields)
+	filteredFields := make(Map, 0, len(e.Fields))
+	for _, fs := range l.fields.append(e.Fields) {
+		if fs.LevelFilter != nil && !fs.LevelFilter(l.level) {
+			continue
+		}
+		filteredFields = append(filteredFields, fs)
+	}
+	e.Fields = filteredFields
 	e.LoggerNames = appendNames(l.names, e.LoggerNames...)
 
 	for _, s := range l.sinks {
@@ -227,8 +234,22 @@ func appendNames(names []string, names2 ...string) []string {
 
 // Field represents a log field.
 type Field struct {
-	Name  string
-	Value interface{}
+	Name  string      `json:"name,omitempty"`
+	Value interface{} `json:"value,omitempty"`
+
+	// LevelFilter, if set, instructs the logger to only process this field
+	// if it processing entries at the given level.
+	LevelFilter func(Level) bool `json:"-"`
+}
+
+// DebugF is a convenience constructor for Field, with LevelFilter only
+// allowing Debug level entries.
+func DebugF(name string, value interface{}) Field {
+	f := F(name, value)
+	f.LevelFilter = func(l Level) bool {
+		return l == LevelDebug
+	}
+	return f
 }
 
 // F is a convenience constructor for Field.

diff --git a/slog_test.go b/slog_test.go
@@ -51,6 +51,23 @@ func TestLogger(t *testing.T) {
 		assert.Equal(t, "sinks", s1, s2)
 	})
 
+	t.Run("levelFilter", func(t *testing.T) {
+		t.Parallel()
+
+		s := &fakeSink{}
+		l := slog.Make(s)
+
+		l.Info(bg, "wow", slog.Error(io.EOF), slog.DebugF("nosee", "me"))
+
+		assert.Len(t, "entries", 1, s.entries)
+		assert.Len(t, "fields", 1, s.entries[0].Fields)
+
+		l = l.Leveled(slog.LevelDebug)
+		l.Info(bg, "wow", slog.Error(io.EOF), slog.DebugF("nosee", "me"))
+		assert.Len(t, "entries", 2, s.entries)
+		assert.Len(t, "fields", 2, s.entries[1].Fields)
+	})
+
 	t.Run("helper", func(t *testing.T) {
 		t.Parallel()
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		0001-01-01 00:00:00.000 [warn] obj="[{Name:obj1 Value:{foo:1 bar:2 dra:[98 108 97 104]}} {Name:obj2 Value:{foo:3 bar:4 dra:[98 108 97 104]}}]" map={"key1":"value1"}
		0001-01-01 00:00:00.000 [warn] obj={"obj1":"{foo:1 bar:2 dra:[98 108 97 104]}","obj2":"{foo:3 bar:4 dra:[98 108 97 104]}"} map={"key1":"value1"}