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Merged
nrwiersma merged 1 commit into from
Apr 8, 2026
Merged

feat: support groups #122

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15 changes: 15 additions & 0 deletions ctx/ctx.go
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Original file line number Diff line number Diff line change
Expand Up @@ -188,6 +188,21 @@ func Interface(k string, v any) logger.Field {
}
}

// Group returns a field that writes all the given fields inside a named group.
func Group(name string, fields ...logger.Field) logger.Field {
return func(e *logger.Event) {
if len(fields) == 0 {
return
}

e.OpenGroup(name)
for _, f := range fields {
f(e)
}
e.CloseGroup()
}
}

// Span represents an open telemetry span.
type Span interface {
IsRecording() bool
Expand Down
39 changes: 26 additions & 13 deletions event.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,30 +17,43 @@ var eventPool = &sync.Pool{

// Event is a log event.
type Event struct {
fmtr Formatter
buf *bytes.Buffer
fmtr Formatter
buf *bytes.Buffer
prefix []byte
}

func newEvent(fmtr Formatter) *Event {
e := eventPool.Get().(*Event)
e.fmtr = fmtr
e.buf.Reset()
e.prefix = e.prefix[:0]
return e
}

func putEvent(e *Event) {
eventPool.Put(e)
}

// OpenGroup opens a named group in the event output. Every OpenGroup call
// must be paired with a matching CloseGroup call.
func (e *Event) OpenGroup(name string) {
e.prefix = e.fmtr.AppendGroupStart(e.buf, e.prefix, name)
}

// CloseGroup closes the most recently opened group.
func (e *Event) CloseGroup() {
e.prefix = e.fmtr.AppendGroupEnd(e.buf, e.prefix)
}

// AppendString appends a string to the event.
func (e *Event) AppendString(k, s string) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendString(e.buf, s)
}

// AppendStrings appends strings to the event.
func (e *Event) AppendStrings(k string, s []string) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendArrayStart(e.buf)
for i, ss := range s {
if i > 0 {
Expand All @@ -53,7 +66,7 @@ func (e *Event) AppendStrings(k string, s []string) {

// AppendBytes appends bytes to the event.
func (e *Event) AppendBytes(k string, p []byte) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendArrayStart(e.buf)
for i, b := range p {
if i > 0 {
Expand All @@ -66,19 +79,19 @@ func (e *Event) AppendBytes(k string, p []byte) {

// AppendBool appends a bool to the event.
func (e *Event) AppendBool(k string, b bool) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendBool(e.buf, b)
}

// AppendInt appends an int to the event.
func (e *Event) AppendInt(k string, i int64) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendInt(e.buf, i)
}

// AppendInts appends ints to the event.
func (e *Event) AppendInts(k string, a []int) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendArrayStart(e.buf)
for i, ii := range a {
if i > 0 {
Expand All @@ -91,30 +104,30 @@ func (e *Event) AppendInts(k string, a []int) {

// AppendUint appends a uint to the event.
func (e *Event) AppendUint(k string, i uint64) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendUint(e.buf, i)
}

// AppendFloat appends a float to the event.
func (e *Event) AppendFloat(k string, f float64) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendFloat(e.buf, f)
}

// AppendTime appends a time to the event.
func (e *Event) AppendTime(k string, d time.Time) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendTime(e.buf, d)
}

// AppendDuration appends a duration to the event.
func (e *Event) AppendDuration(k string, d time.Duration) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendDuration(e.buf, d)
}

// AppendInterface appends a interface to the event.
func (e *Event) AppendInterface(k string, v any) {
e.fmtr.AppendKey(e.buf, k)
e.fmtr.AppendKey(e.buf, e.prefix, k)
e.fmtr.AppendInterface(e.buf, v)
}
67 changes: 62 additions & 5 deletions format.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,9 @@ type Formatter interface {
AppendArrayStart(buf *bytes.Buffer)
AppendArraySep(buf *bytes.Buffer)
AppendArrayEnd(buf *bytes.Buffer)
AppendKey(buf *bytes.Buffer, key string)
AppendKey(buf *bytes.Buffer, prefix []byte, key string)
AppendGroupStart(buf *bytes.Buffer, prefix []byte, name string) []byte
AppendGroupEnd(buf *bytes.Buffer, prefix []byte) []byte
AppendString(buf *bytes.Buffer, s string)
AppendBool(buf *bytes.Buffer, b bool)
AppendInt(buf *bytes.Buffer, i int64)
Expand Down Expand Up @@ -86,12 +88,32 @@ func (j *json) AppendArrayEnd(buf *bytes.Buffer) {
buf.WriteByte(']')
}

func (j *json) AppendKey(buf *bytes.Buffer, key string) {
buf.WriteString(`,"`)
func (j *json) AppendKey(buf *bytes.Buffer, _ []byte, key string) {
if buf.Peek() != '{' {
buf.WriteString(`,"`)
} else {
buf.WriteByte('"')
}
buf.WriteString(key)
buf.WriteString(`":`)
}

func (j *json) AppendGroupStart(buf *bytes.Buffer, prefix []byte, name string) []byte {
if buf.Peek() != '{' {
buf.WriteString(`,"`)
} else {
buf.WriteByte('"')
}
buf.WriteString(name)
buf.WriteString(`":{`)
return prefix
}

func (j *json) AppendGroupEnd(buf *bytes.Buffer, prefix []byte) []byte {
buf.WriteByte('}')
return prefix
}

func (j *json) AppendString(buf *bytes.Buffer, s string) {
appendString(buf, s, true)
}
Expand Down Expand Up @@ -184,12 +206,24 @@ func (l *logfmt) AppendArraySep(buf *bytes.Buffer) {

func (l *logfmt) AppendArrayEnd(_ *bytes.Buffer) {}

func (l *logfmt) AppendKey(buf *bytes.Buffer, key string) {
func (l *logfmt) AppendKey(buf *bytes.Buffer, prefix []byte, key string) {
buf.WriteByte(' ')
if len(prefix) > 0 {
buf.Write(prefix)
}
buf.WriteString(key)
buf.WriteByte('=')
}

func (l *logfmt) AppendGroupStart(_ *bytes.Buffer, prefix []byte, name string) []byte {
prefix = append(prefix, name...)
return append(prefix, '.')
}

func (l *logfmt) AppendGroupEnd(_ *bytes.Buffer, prefix []byte) []byte {
return trimLastGroup(prefix)
}

func (l *logfmt) AppendString(buf *bytes.Buffer, s string) {
appendString(buf, s, l.needsQuote(s))
}
Expand Down Expand Up @@ -327,7 +361,7 @@ func (c *console) AppendArraySep(buf *bytes.Buffer) {

func (c *console) AppendArrayEnd(_ *bytes.Buffer) {}

func (c *console) AppendKey(buf *bytes.Buffer, key string) {
func (c *console) AppendKey(buf *bytes.Buffer, prefix []byte, key string) {
buf.WriteByte(' ')

col := newColor(colorCyan)
Expand All @@ -336,11 +370,23 @@ func (c *console) AppendKey(buf *bytes.Buffer, key string) {
}

withColor(col, buf, func() {
if len(prefix) > 0 {
buf.Write(prefix)
}
buf.WriteString(key)
buf.WriteByte('=')
})
}

func (c *console) AppendGroupStart(_ *bytes.Buffer, prefix []byte, name string) []byte {
prefix = append(prefix, name...)
return append(prefix, '.')
}

func (c *console) AppendGroupEnd(_ *bytes.Buffer, prefix []byte) []byte {
return trimLastGroup(prefix)
}

func (c *console) AppendString(buf *bytes.Buffer, s string) {
appendString(buf, s, false)
}
Expand Down Expand Up @@ -456,3 +502,14 @@ func tryAddASCII(buf *bytes.Buffer, b byte) bool {
}
return true
}

// trimLastGroup removes the last "name." segment from prefix by scanning
// backwards for the dot preceding the final segment.
func trimLastGroup(prefix []byte) []byte {
for i := len(prefix) - 2; i >= 0; i-- {
if prefix[i] == '.' {
return prefix[:i+1]
}
}
return prefix[:0]
}
95 changes: 92 additions & 3 deletions format_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ func TestJsonFormat(t *testing.T) {
buf := bytes.NewBuffer(512)
fmtr.AppendBeginMarker(buf)
fmtr.WriteMessage(buf, time.Unix(123, 0).UTC(), logger.Error, "some message")
fmtr.AppendKey(buf, "error")
fmtr.AppendKey(buf, nil, "error")
fmtr.AppendString(buf, "some error")
fmtr.AppendEndMarker(buf)
fmtr.AppendLineBreak(buf)
Expand Down Expand Up @@ -171,13 +171,51 @@ func TestJsonFormat_Interface(t *testing.T) {
assert.Equal(t, `"{Name:test}"null`, string(buf.Bytes()))
}

func TestJsonFormat_Group(t *testing.T) {
fmtr := logger.JSONFormat()

buf := bytes.NewBuffer(512)
fmtr.AppendBeginMarker(buf)
fmtr.WriteMessage(buf, time.Time{}, logger.Info, "msg")
prefix := fmtr.AppendGroupStart(buf, nil, "db")
fmtr.AppendKey(buf, prefix, "host")
fmtr.AppendString(buf, "localhost")
fmtr.AppendKey(buf, prefix, "port")
fmtr.AppendInt(buf, 5432)
fmtr.AppendGroupEnd(buf, prefix)
fmtr.AppendKey(buf, nil, "other")
fmtr.AppendString(buf, "val")
fmtr.AppendEndMarker(buf)

want := `{"lvl":"info","msg":"msg","db":{"host":"localhost","port":5432},"other":"val"}`
assert.Equal(t, want, string(buf.Bytes()))
}

func TestJsonFormat_NestedGroup(t *testing.T) {
fmtr := logger.JSONFormat()

buf := bytes.NewBuffer(512)
fmtr.AppendBeginMarker(buf)
fmtr.WriteMessage(buf, time.Time{}, logger.Info, "msg")
outer := fmtr.AppendGroupStart(buf, nil, "outer")
inner := fmtr.AppendGroupStart(buf, outer, "inner")
fmtr.AppendKey(buf, inner, "k")
fmtr.AppendString(buf, "v")
fmtr.AppendGroupEnd(buf, inner)
fmtr.AppendGroupEnd(buf, outer)
fmtr.AppendEndMarker(buf)

want := `{"lvl":"info","msg":"msg","outer":{"inner":{"k":"v"}}}`
assert.Equal(t, want, string(buf.Bytes()))
}

func TestLogfmtFormat(t *testing.T) {
fmtr := logger.LogfmtFormat()

buf := bytes.NewBuffer(512)
fmtr.AppendBeginMarker(buf)
fmtr.WriteMessage(buf, time.Unix(123, 0).UTC(), logger.Error, "some message")
fmtr.AppendKey(buf, "error")
fmtr.AppendKey(buf, nil, "error")
fmtr.AppendString(buf, "some error")
fmtr.AppendEndMarker(buf)
fmtr.AppendLineBreak(buf)
Expand Down Expand Up @@ -333,13 +371,48 @@ func TestLogfmtFormat_Interface(t *testing.T) {
assert.Equal(t, `{Name:test}`, string(buf.Bytes()))
}

func TestLogfmtFormat_Group(t *testing.T) {
fmtr := logger.LogfmtFormat()

buf := bytes.NewBuffer(512)
fmtr.WriteMessage(buf, time.Time{}, logger.Info, "msg")
prefix := fmtr.AppendGroupStart(buf, nil, "db")
fmtr.AppendKey(buf, prefix, "host")
fmtr.AppendString(buf, "localhost")
fmtr.AppendKey(buf, prefix, "port")
fmtr.AppendInt(buf, 5432)
prefix = fmtr.AppendGroupEnd(buf, prefix)
fmtr.AppendKey(buf, prefix, "other")
fmtr.AppendString(buf, "val")

want := `lvl=info msg=msg db.host=localhost db.port=5432 other=val`
assert.Equal(t, want, string(buf.Bytes()))
}

func TestLogfmtFormat_NestedGroup(t *testing.T) {
fmtr := logger.LogfmtFormat()

buf := bytes.NewBuffer(512)
fmtr.WriteMessage(buf, time.Time{}, logger.Info, "msg")
outer := fmtr.AppendGroupStart(buf, nil, "a")
inner := fmtr.AppendGroupStart(buf, outer, "b")
fmtr.AppendKey(buf, inner, "k")
fmtr.AppendString(buf, "v")
outer = fmtr.AppendGroupEnd(buf, inner)
fmtr.AppendKey(buf, outer, "x")
fmtr.AppendString(buf, "y")

want := `lvl=info msg=msg a.b.k=v a.x=y`
assert.Equal(t, want, string(buf.Bytes()))
}

func TestConsoleFormat(t *testing.T) {
fmtr := logger.ConsoleFormat()

buf := bytes.NewBuffer(512)
fmtr.AppendBeginMarker(buf)
fmtr.WriteMessage(buf, time.Unix(123, 0).UTC(), logger.Error, "some message")
fmtr.AppendKey(buf, "error")
fmtr.AppendKey(buf, nil, "error")
fmtr.AppendString(buf, "some error")
fmtr.AppendEndMarker(buf)
fmtr.AppendLineBreak(buf)
Expand Down Expand Up @@ -482,3 +555,19 @@ func TestConsoleFormat_Interface(t *testing.T) {

assert.Equal(t, `{Name:test}`, string(buf.Bytes()))
}

func TestConsoleFormat_Group(t *testing.T) {
fmtr := logger.ConsoleFormat()

buf := bytes.NewBuffer(512)
fmtr.WriteMessage(buf, time.Time{}, logger.Info, "msg")
prefix := fmtr.AppendGroupStart(buf, nil, "db")
fmtr.AppendKey(buf, prefix, "host")
fmtr.AppendString(buf, "localhost")
prefix = fmtr.AppendGroupEnd(buf, prefix)
fmtr.AppendKey(buf, prefix, "other")
fmtr.AppendString(buf, "val")

want := "\x1b[32mINFO\x1b[0m msg \x1b[36mdb.host=\x1b[0mlocalhost \x1b[36mother=\x1b[0mval"
assert.Equal(t, want, string(buf.Bytes()))
}
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