Adds Objects field type to logger fields, events, and context (#736)

* Improve code coverage before adding Objects

* Refactor ErrorMarshal tests.

Added testing of the error marshal in Fields Reduce the duplication of the test data and make it clearer what the "wants" represent.

* Add Objects support to Fields, Event, Context

* Add support for Object Fields

Passed as []LogObjectMarshaler.

* Fixed syntax of ExampleContext_Objects

Seems 1.24 accepts variadic for arrays and understands covariance but 1.21 doesn't.

* Fix problem with []uint8 serialized as a Base64 string

* Better syntax in the example use of Objects

array_test.go

@@ -26,6 +26,7 @@ func TestArray(t *testing.T) {
 		Bytes([]byte("b")).
 		Hex([]byte{0x1f}).
 		RawJSON([]byte(`{"some":"json"}`)).
+		RawJSON([]byte(`{"longer":[1111,2222,3333,4444,5555]}`)).
 		Time(time.Time{}).
 		IPAddr(net.IP{192, 168, 0, 10}).
 		IPPrefix(net.IPNet{IP: net.IP{127, 0, 0, 0}, Mask: net.CIDRMask(24, 32)}).
@@ -53,7 +54,7 @@ func TestArray(t *testing.T) {
 		}).
 		Type(3.14)
 
-	want := `[true,1,2,3,4,5,6,7,8,9,10,11.98122,12.987654321,"a","b","1f",{"some":"json"},"0001-01-01T00:00:00Z","192.168.0.10","127.0.0.0/24","01:23:45:67:89:ab",{"Pub":"A","tag":"j"},{"name":"zot","age":-35},0,{"bar":"baz","n":1},null,"failure",{"error":"OOPS"},{"name":"zit","age":-22},"float64"]`
+	want := `[true,1,2,3,4,5,6,7,8,9,10,11.98122,12.987654321,"a","b","1f",{"some":"json"},{"longer":[1111,2222,3333,4444,5555]},"0001-01-01T00:00:00Z","192.168.0.10","127.0.0.0/24","01:23:45:67:89:ab",{"Pub":"A","tag":"j"},{"name":"zot","age":-35},0,{"bar":"baz","n":1},null,"failure",{"error":"OOPS"},{"name":"zit","age":-22},"float64"]`
 	if got := decodeObjectToStr(a.write([]byte{})); got != want {
 		t.Errorf("Array.write()\ngot:  %s\nwant: %s", got, want)
 	}

benchmark_test.go

@@ -184,6 +184,9 @@ func BenchmarkLogFieldType(b *testing.B) {
 		"Object": func(e *Event) *Event {
 			return e.Object("k", fixtures.Objects[0])
 		},
+		"Objects": func(e *Event) *Event {
+			return e.Objects("k", fixtures.Objects)
+		},
 		"Timestamp": func(e *Event) *Event {
 			return e.Timestamp()
 		},
@@ -309,6 +312,9 @@ func BenchmarkContextFieldType(b *testing.B) {
 		"Object": func(c Context) Context {
 			return c.Object("k", fixtures.Objects[0])
 		},
+		"Objects": func(c Context) Context {
+			return c.Objects("k", fixtures.Objects)
+		},
 		"Timestamp": func(c Context) Context {
 			return c.Timestamp()
 		},

binary_test.go

@@ -232,6 +232,7 @@ func (u User) MarshalZerologObject(e *Event) {
 
 type Users []User
 
+// User implements LogObjectMarshaler
 func (uu Users) MarshalZerologArray(a *Array) {
 	for _, u := range uu {
 		a.Object(u)
@@ -289,6 +290,25 @@ func ExampleEvent_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleContext_Objects() {
+	// In go, arrays are type invariant so even if you have a variable u of type []User array and User implements
+	// the LogObjectMarshaler interface, you cannot pass that to func that takes an []LogObjectMarshaler array in the
+	// Objects call. In 1.24+ it allows passing the variadic covariant slice (e.g. u...) but the unit test needs to
+	// work in earlier versions so we'll declare the array as []LogObjectMarshaler here.
+	u := []LogObjectMarshaler{User{"John", 35, time.Time{}}, User{"Bob", 55, time.Time{}}}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		Objects("users", u).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
+}
+
 func ExampleEvent_EmbedObject() {
 	price := Price{val: 6449, prec: 2, unit: "$"}
 

context.go

@@ -64,6 +64,15 @@ func (c Context) Object(key string, obj LogObjectMarshaler) Context {
 	return c
 }
 
+// Object marshals an object that implement the LogObjectMarshaler interface.
+func (c Context) Objects(key string, objs []LogObjectMarshaler) Context {
+	e := newEvent(LevelWriterAdapter{io.Discard}, 0)
+	e.Objects(key, objs)
+	c.l.context = enc.AppendObjectData(c.l.context, e.buf)
+	putEvent(e)
+	return c
+}
+
 // EmbedObject marshals and Embeds an object that implement the LogObjectMarshaler interface.
 func (c Context) EmbedObject(obj LogObjectMarshaler) Context {
 	e := newEvent(LevelWriterAdapter{io.Discard}, 0)

event.go

@@ -228,6 +228,22 @@ func (e *Event) Object(key string, obj LogObjectMarshaler) *Event {
 	return e
 }
 
+// Objects adds the field key with obj as an array of objects that implement the LogObjectMarshaler interface.
+func (e *Event) Objects(key string, objs []LogObjectMarshaler) *Event {
+	if e == nil {
+		return e
+	}
+	e.buf = enc.AppendArrayStart(enc.AppendKey(e.buf, key))
+	for i, obj := range objs {
+		e.buf = appendObject(e.buf, obj)
+		if i < (len(objs) - 1) {
+			e.buf = enc.AppendArrayDelim(e.buf)
+		}
+	}
+	e.buf = enc.AppendArrayEnd(e.buf)
+	return e
+}
+
 // Func allows an anonymous func to run only if the event is enabled.
 func (e *Event) Func(f func(e *Event)) *Event {
 	if e != nil && e.Enabled() {

event_test.go

@@ -5,6 +5,8 @@ package zerolog
 import (
 	"bytes"
 	"errors"
+	"io"
+	"os"
 	"strings"
 	"testing"
 )
@@ -169,7 +171,7 @@ func TestEvent_WithNilEvent(t *testing.T) {
 			return e.RawCBOR("k", fixtures.RawCBOR)
 		},
 		"RawJSON": func() *Event {
-			return e.RawJSON("k", fixtures.RawJSON)
+			return e.RawJSON("k", fixtures.RawJSONs[0])
 		},
 		"Str": func() *Event {
 			return e.Str("k", fixtures.Strings[0])
@@ -221,6 +223,9 @@ func TestEvent_WithNilEvent(t *testing.T) {
 		"Object": func() *Event {
 			return e.Object("k", fixtures.Objects[0])
 		},
+		"Objects": func() *Event {
+			return e.Objects("k", fixtures.Objects)
+		},
 		"EmbedObject": func() *Event {
 			return e.EmbedObject(fixtures.Objects[0])
 		},
@@ -301,3 +306,78 @@ func TestEvent_MsgFunc(t *testing.T) {
 		t.Errorf("Event.MsgFunc() = %q, want %q", got, want)
 	}
 }
+
+func TestEvent_DoneHandler(t *testing.T) {
+	e := newEvent(nil, InfoLevel)
+
+	// Set up a done handler to capture calls
+	var called bool
+	var capturedMsg string
+	e.done = func(msg string) {
+		called = true
+		capturedMsg = msg
+	}
+
+	// Trigger msg via Msg
+	e.Msg("test message")
+
+	// Assert the handler was called with the correct message
+	if !called {
+		t.Error("Done handler was not called")
+	}
+	if capturedMsg != "test message" {
+		t.Errorf("Expected message 'test message', got '%s'", capturedMsg)
+	}
+}
+
+type badLevelWriter struct {
+	err error
+}
+
+func (w *badLevelWriter) WriteLevel(level Level, p []byte) (n int, err error) {
+	return 0, w.err
+}
+
+func (w *badLevelWriter) Write(p []byte) (n int, err error) {
+	return 0, w.err
+}
+
+func TestEvent_Msg_ErrorHandlerNil(t *testing.T) {
+	// Save original ErrorHandler and restore after test
+	originalErrorHandler := ErrorHandler
+	ErrorHandler = nil
+	defer func() { ErrorHandler = originalErrorHandler }()
+
+	// Create a LevelWriter that always returns an error
+	mockWriter := &badLevelWriter{err: errors.New("write error")}
+
+	e := newEvent(mockWriter, InfoLevel)
+	if e == nil {
+		t.Fatal("Event should not be nil")
+	}
+
+	// Capture stderr
+	oldStderr := os.Stderr
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	os.Stderr = w
+
+	// Call Msg to trigger write error
+	e.Msg("test message")
+
+	// Restore stderr and read captured output
+	w.Close()
+	os.Stderr = oldStderr
+	captured, err := io.ReadAll(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Assert the error message was printed to stderr
+	expected := "zerolog: could not write event: write error\n"
+	if string(captured) != expected {
+		t.Errorf("Expected stderr output %q, got %q", expected, string(captured))
+	}
+}

fields.go

@@ -113,6 +113,15 @@ func appendFieldList(dst []byte, kvList []interface{}, stack bool) []byte {
 				}
 			}
 			dst = enc.AppendArrayEnd(dst)
+		case []LogObjectMarshaler:
+			dst = enc.AppendArrayStart(dst)
+			for i, obj := range val {
+				dst = appendObject(dst, obj)
+				if i < (len(val) - 1) {
+					dst = enc.AppendArrayDelim(dst)
+				}
+			}
+			dst = enc.AppendArrayEnd(dst)
 		case bool:
 			dst = enc.AppendBool(dst, val)
 		case int:

fixtures_test.go

@@ -47,9 +47,9 @@ type fieldFixtures struct {
 	IPAddrs   []net.IP
 	IPPfxs    []net.IPNet
 	MACAddr   net.HardwareAddr
-	Objects   []fixtureObj
+	Objects   []LogObjectMarshaler
 	RawCBOR   []byte
-	RawJSON   []byte
+	RawJSONs  [][]byte
 	Stringers []fmt.Stringer
 	Strings   []string
 	Times     []time.Time
@@ -101,17 +101,17 @@ func makeFieldFixtures() *fieldFixtures {
 		{"I", "b", 3},
 		{"J", "a", 4},
 	}
-	objects := []fixtureObj{
-		{"a", "z", 1},
-		{"b", "y", 2},
-		{"c", "x", 3},
-		{"d", "w", 4},
-		{"e", "v", 5},
-		{"f", "u", 6},
-		{"g", "t", 7},
-		{"h", "s", 8},
-		{"i", "r", 9},
-		{"j", "q", 10},
+	objects := []LogObjectMarshaler{
+		fixtureObj{"a", "z", 1},
+		fixtureObj{"b", "y", 2},
+		fixtureObj{"c", "x", 3},
+		fixtureObj{"d", "w", 4},
+		fixtureObj{"e", "v", 5},
+		fixtureObj{"f", "u", 6},
+		fixtureObj{"g", "t", 7},
+		fixtureObj{"h", "s", 8},
+		fixtureObj{"i", "r", 9},
+		fixtureObj{"j", "q", 10},
 	}
 	ipAddrV4 := net.IP{192, 168, 0, 1}
 	ipAddrV6 := net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}
@@ -123,7 +123,7 @@ func makeFieldFixtures() *fieldFixtures {
 	errs := []error{errors.New("a"), errors.New("b"), errors.New("c"), errors.New("d"), errors.New("e"), nil, errorObjectMarshalerImpl{fmt.Errorf("oops")}}
 	ctx := context.Background()
 	stringers := []fmt.Stringer{ipAddrs[0], durations[0]}
-	rawJSON := []byte(`{"some":"json"}`)
+	rawJSONs := [][]byte{[]byte(`{"some":"json"}`), []byte(`{"longer":[1111,2222,3333,4444,5555]}`)}
 	rawCBOR := []byte{0xA1, 0x64, 0x73, 0x6F, 0x6D, 0x65, 0x64, 0x61, 0x74, 0x61} // {"some":"data"}
 
 	return &fieldFixtures{
@@ -150,7 +150,7 @@ func makeFieldFixtures() *fieldFixtures {
 		MACAddr:    macAddr,
 		Objects:    objects,
 		RawCBOR:    rawCBOR,
-		RawJSON:    rawJSON,
+		RawJSONs:   rawJSONs,
 		Stringers:  stringers,
 		Strings:    strings,
 		Times:      times,

internal/cbor/string_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"encoding/hex"
 	"testing"
+
+	"github.com/rs/zerolog/internal"
 )
 
 var encodeStringTests = []struct {
@@ -129,13 +131,50 @@ func TestAppendStrings(t *testing.T) {
 	}
 	got = enc.AppendStrings([]byte{}, array)
 	if !bytes.Equal(got, want) {
-		t.Errorf("AppendStrings(%v)\ngot:  0x%s\nwant: 0x%s",
+		t.Errorf("AppendStrings(%v)\ngot:  %s\nwant: %s",
 			array,
 			hex.EncodeToString(got),
 			hex.EncodeToString(want))
 	}
 }
 
+func TestAppendStringer(t *testing.T) {
+	oldJSONMarshalFunc := JSONMarshalFunc
+	defer func() {
+		JSONMarshalFunc = oldJSONMarshalFunc
+	}()
+
+	JSONMarshalFunc = func(v interface{}) ([]byte, error) {
+		return internal.InterfaceMarshalFunc(v)
+	}
+
+	for _, tt := range internal.EncodeStringerTests {
+		got := enc.AppendStringer([]byte{}, tt.In)
+		want := []byte(tt.Binary)
+		if !bytes.Equal(got, want) {
+			t.Errorf("AppendStrings(%v)\ngot:  %s\nwant: %s",
+				tt.In,
+				hex.EncodeToString(got),
+				hex.EncodeToString(want))
+		}
+	}
+}
+
+func TestAppendStringers(t *testing.T) {
+	for _, tt := range internal.EncodeStringersTests {
+		want := make([]byte, 0)
+		want = append(want, []byte(tt.Binary)...)
+
+		got := enc.AppendStringers([]byte{}, tt.In)
+		if !bytes.Equal(got, want) {
+			t.Errorf("AppendStrings(%v)\ngot:  %s\nwant: %s",
+				tt,
+				hex.EncodeToString(got),
+				hex.EncodeToString(want))
+		}
+	}
+}
+
 func TestAppendBytes(t *testing.T) {
 	for _, tt := range encodeByteTests {
 		b := enc.AppendBytes([]byte{}, tt.plain)
@@ -155,6 +194,7 @@ func TestAppendBytes(t *testing.T) {
 		t.Errorf("appendString(%q) = %#q, want %#q", inp, got, want)
 	}
 }
+
 func BenchmarkAppendString(b *testing.B) {
 	tests := map[string]string{
 		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,

internal/testcases.go

@@ -308,22 +308,24 @@ var EncodeStringsTests = []struct {
 }
 
 var EncodeStringerTests = []struct {
-	In  fmt.Stringer
-	Out string
+	In     fmt.Stringer
+	Out    string
+	Binary string
 }{
-	{nil, `null`},
-	{fmt.Stringer(nil), `null`},
-	{net.IPv4bcast, `"255.255.255.255"`},
+	{nil, `null`, "\xf6"},
+	{fmt.Stringer(nil), `null`, "\xf6"},
+	{net.IPv4bcast, `"255.255.255.255"`, "\x6f\x32\x35\x35\x2e\x32\x35\x35\x2e\x32\x35\x35\x2e\x32\x35\x35"},
 }
 
 var EncodeStringersTests = []struct {
-	In  []fmt.Stringer
-	Out string
+	In     []fmt.Stringer
+	Out    string
+	Binary string
 }{
-	{nil, `[]`},
-	{[]fmt.Stringer{}, `[]`},
-	{[]fmt.Stringer{net.IPv4bcast}, `["255.255.255.255"]`},
-	{[]fmt.Stringer{net.IPv4allsys, net.IPv4allrouter}, `["224.0.0.1","224.0.0.2"]`},
+	{nil, `[]`, "\x9f\xff"},
+	{[]fmt.Stringer{}, `[]`, "\x9f\xff"},
+	{[]fmt.Stringer{net.IPv4bcast}, `["255.255.255.255"]`, "\x9f\x6f255.255.255.255\xff"},
+	{[]fmt.Stringer{net.IPv4allsys, net.IPv4allrouter}, `["224.0.0.1","224.0.0.2"]`, "\x9f\x69224.0.0.1\x69224.0.0.2\xff"},
 }
 
 var TimeIntegerTestcases = []struct {

log/log_example_test.go

@@ -1,8 +1,11 @@
+//go:build !binary_log
 // +build !binary_log
 
 package log_test
 
 import (
+	"bytes"
+	"context"
 	"errors"
 	"flag"
 	"os"
@@ -119,7 +122,13 @@ func ExampleFatal() {
 	// Outputs: {"level":"fatal","time":1199811905,"error":"A repo man spends his life getting into tense situations","service":"myservice","message":"Cannot start myservice"}
 }
 
-// TODO: Panic
+// Example of a log at a particular "level" (in this case, "panic")
+func ExamplePanic() {
+	setup()
+
+	log.Panic().Msg("Cannot start")
+	// Outputs: {"level":"panic","time":1199811905,"message":"Cannot start"} then panics
+}
 
 // This example uses command-line flags to demonstrate various outputs
 // depending on the chosen log level.
@@ -147,16 +156,91 @@ func Example() {
 	// Output: {"level":"info","time":1199811905,"message":"This message appears when log level set to Debug or Info"}
 }
 
-// TODO: Output
+// Example of using the Output function in the log package to change the output destination
+func ExampleOutput() {
+	setup()
 
-// TODO: With
+	out := &bytes.Buffer{}
+	tee := log.Output(out)
+	tee.Info().Msg("hello world")
+	written := out.Len()
 
-// TODO: Level
+	log.Info().Int("bytes", written).Msg("wrote")
+	// Output: {"level":"info","bytes":59,"time":1199811905,"message":"wrote"}
+}
 
-// TODO: Sample
+// Example of using the With function to add context fields
+func ExampleWith() {
+	setup()
 
-// TODO: Hook
+	// you have to assign the result of With() to a new Logger and can't inline the level calls
+	// because they need a *Logger receiver
+	augmented := log.With().Str("service", "myservice").Logger()
+	augmented.Info().Msg("hello world")
+	// Output: {"level":"info","service":"myservice","time":1199811905,"message":"hello world"}
+}
 
-// TODO: WithLevel
+// Example of using the Level function to set the log level
+func ExampleLevel() {
+	setup()
 
-// TODO: Ctx
+	// you have to assign the result of Level() to a new Logger and can't inline the level calls
+	// because they need a *Logger receiver
+	leveled := log.Level(zerolog.ErrorLevel)
+	leveled.Info().Msg("hello world")
+	leveled.Error().Msg("I said HELLO")
+	// Output: {"level":"error","time":1199811905,"message":"I said HELLO"}
+}
+
+type valueKeyType int
+
+var valueKey valueKeyType = 42
+
+var captainHook = zerolog.HookFunc(func(e *zerolog.Event, l zerolog.Level, msg string) {
+	e.Interface("key", e.GetCtx().Value(valueKey))
+	e.Bool("is_error", l > zerolog.ErrorLevel)
+	e.Int("msg_len", len(msg))
+})
+
+// Example of using the Logger Hook function to add hooks
+func ExampleLogger_Hook() {
+	setup()
+
+	hooked := log.Hook(captainHook)
+	hooked.Info().Msg("watch out!")
+	// Output: {"level":"info","time":1199811905,"key":null,"is_error":false,"msg_len":10,"message":"watch out!"}
+}
+
+// Example of using the WithLevel function to set the log level
+func ExampleWithLevel() {
+	setup()
+
+	// you have to assign the result of Level() to a new Logger and can't inline the level calls
+	// because they need a *Logger receiver
+	event := log.WithLevel(zerolog.ErrorLevel)
+	event.Msg("taxes are due")
+	// Output: {"level":"error","time":1199811905,"message":"taxes are due"}
+}
+
+// Example of using the Ctx function in the log package to log with context
+func ExampleCtx() {
+	setup()
+
+	hooked := log.Hook(captainHook)
+	ctx := context.WithValue(context.Background(), valueKey, "12345")
+	logger := hooked.With().Ctx(ctx).Logger()
+	log.Ctx(logger.WithContext(ctx)).Info().Msg("hello world")
+	// Output: {"level":"info","time":1199811905,"key":"12345","is_error":false,"msg_len":11,"message":"hello world"}
+}
+
+// Example of using the Sample function in the log package to set a sampler
+func ExampleSample() {
+	setup()
+
+	sampled := log.Sample(&zerolog.BasicSampler{N: 2})
+	sampled.Info().Msg("hello world")
+	sampled.Info().Msg("I said, hello world")
+	sampled.Info().Msg("Can you here me now world")
+	// Output: {"level":"info","time":1199811905,"message":"hello world"}
+	// {"level":"info","time":1199811905,"message":"Can you here me now world"}
+}

log_example_test.go

@@ -435,6 +435,20 @@ func ExampleContext_Object() {
 
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
+func ExampleContext_Objects() {
+	// User implements zerolog.LogObjectMarshaler
+	u := User{"John", 35, time.Time{}}
+	u2 := User{"Bono", 54, time.Time{}}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		Objects("users", []zerolog.LogObjectMarshaler{u, u2}).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bono","age":54,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
+}
 
 func ExampleContext_EmbedObject() {
 

log_test.go

@@ -3,6 +3,7 @@ package zerolog
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math"
@@ -162,7 +163,7 @@ func TestWithPlurals(t *testing.T) {
 		Strs("strings_nil", nil).
 		Stringers("stringers", []fmt.Stringer{net.IP{127, 0, 0, 1}, nil}).
 		Stringers("stringers_nil", nil).
-		Errs("errs", []error{errors.New("some error"), errors.New("some other error")}).
+		Errs("errs", []error{errors.New("some error"), errors.New("some other error"), nil, errorObjectMarshalerImpl{fmt.Errorf("oops")}}).
 		Bools("bool", []bool{true, false}).
 		Ints("int", []int{1, 2}).
 		Ints8("int8", []int8{2, 3}).
@@ -181,7 +182,7 @@ func TestWithPlurals(t *testing.T) {
 	log := ctx.Logger()
 	log.Log().Msg("")
 	if got, want := decodeIfBinaryToString(out.Bytes()),
-		`{"strings":["foo","bar"],"strings_nil":[],"stringers":["127.0.0.1",null],"stringers_nil":null,"errs":["some error","some other error"],"bool":[true,false],"int":[1,2],"int8":[2,3],"int16":[3,4],"int32":[4,5],"int64":[5,6],"uint":[6,7],"uint8":[7,8],"uint16":[8,9],"uint32":[9,10],"uint64":[10,11],"float32":[1.1,2.2],"float64":[2.2,3.3],"time":["0001-02-03T00:00:00Z","0005-06-07T00:00:00Z"],"dur":[1000,2000]}`+"\n"; got != want {
+		`{"strings":["foo","bar"],"strings_nil":[],"stringers":["127.0.0.1",null],"stringers_nil":null,"errs":["some error","some other error",null,{"error":"OOPS"}],"bool":[true,false],"int":[1,2],"int8":[2,3],"int16":[3,4],"int32":[4,5],"int64":[5,6],"uint":[6,7],"uint8":[7,8],"uint16":[8,9],"uint32":[9,10],"uint64":[10,11],"float32":[1.1,2.2],"float64":[2.2,3.3],"time":["0001-02-03T00:00:00Z","0005-06-07T00:00:00Z"],"dur":[1000,2000]}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -228,12 +229,73 @@ func TestFieldsMap(t *testing.T) {
 		"float32": float32(11),
 		"float64": float64(12),
 		"ipv6":    net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34},
+		"ipnet":   net.IPNet{IP: net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}, Mask: net.CIDRMask(64, 128)},
+		"macaddr": net.HardwareAddr{0x00, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E},
 		"dur":     1 * time.Second,
 		"time":    time.Time{},
 		"obj":     fixtureObj{"a", "b", 1},
+		"objs":    []LogObjectMarshaler{fixtureObj{"a", "b", 1}, fixtureObj{"c", "d", 2}},
 		"any":     struct{ A string }{"test"},
+		"raw":     json.RawMessage(`{"some":"json"}`),
 	}).Msg("")
-	if got, want := decodeIfBinaryToString(out.Bytes()), `{"any":{"A":"test"},"bool":true,"bytes":"bar","dur":1000,"error":"some error","float32":11,"float64":12,"int":1,"int16":3,"int32":4,"int64":5,"int8":2,"ipv6":"2001:db8:85a3::8a2e:370:7334","nil":null,"obj":{"Pub":"a","Tag":"b","priv":1},"string":"foo","time":"0001-01-01T00:00:00Z","uint":6,"uint16":8,"uint32":9,"uint64":10,"uint8":7}`+"\n"; got != want {
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"any":{"A":"test"},"bool":true,"bytes":"bar","dur":1000,"error":"some error","float32":11,"float64":12,"int":1,"int16":3,"int32":4,"int64":5,"int8":2,"ipnet":"2001:db8:85a3::8a2e:370:7334/64","ipv6":"2001:db8:85a3::8a2e:370:7334","macaddr":"00:1a:2b:3c:4d:5e","nil":null,"obj":{"Pub":"a","Tag":"b","priv":1},"objs":[{"Pub":"a","Tag":"b","priv":1},{"Pub":"c","Tag":"d","priv":2}],"raw":{"some":"json"},"string":"foo","time":"0001-01-01T00:00:00Z","uint":6,"uint16":8,"uint32":9,"uint64":10,"uint8":7}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+func TestFieldsMap_Arrays(t *testing.T) {
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]interface{}{
+		"strings":  []string{"foo"},
+		"bools":    []bool{true},
+		"errors":   []error{errors.New("some error")},
+		"ints":     []int{1},
+		"ints8":    []int8{1},
+		"ints16":   []int16{3},
+		"ints32":   []int32{4},
+		"ints64":   []int64{5},
+		"uints":    []uint{6},
+		"uint8s":   []uint8{44},
+		"uints16":  []uint16{8},
+		"uints32":  []uint32{9},
+		"uints64":  []uint64{10},
+		"floats32": []float32{11},
+		"floats64": []float64{12},
+		"ipv6s":    []net.IP{{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}},
+		"ipnets":   []net.IPNet{{IP: net.IP{0x20, 0x01, 0x0d, 0xb8, 0x85, 0xa3, 0x00, 0x00, 0x00, 0x00, 0x8a, 0x2e, 0x03, 0x70, 0x73, 0x34}, Mask: net.CIDRMask(64, 128)}},
+		"macaddrs": []net.HardwareAddr{{0x00, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E}},
+		"durs":     []time.Duration{1 * time.Second},
+		"times":    []time.Time{{}},
+		"objs":     []fixtureObj{{"a", "b", 1}},
+	}).Msg("")
+	// special case: []uint8 is logged as base64 string so we use "," for 44
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"bools":[true],"durs":[1000],"errors":["some error"],"floats32":[11],"floats64":[12],"ints":[1],"ints16":[3],"ints32":[4],"ints64":[5],"ints8":[1],"ipnets":["2001:db8:85a3::8a2e:370:7334/64"],"ipv6s":["2001:db8:85a3::8a2e:370:7334"],"macaddrs":["ABorPE1e"],"objs":[{"Pub":"a","tag":"b"}],"strings":["foo"],"times":["0001-01-01T00:00:00Z"],"uint8s":",","uints":[6],"uints16":[8],"uints32":[9],"uints64":[10]}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+func TestFieldsErr(t *testing.T) {
+	var err error = nil
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]interface{}{
+		"nil":      nil,
+		"nilerror": err,
+		"error":    errors.New("some error"),
+		"loggable": loggableError{errors.New("loggable")},
+		"marshal":  errorObjectMarshalerImpl{fmt.Errorf("oops")},
+	}).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"error":"some error","loggable":{"message":"loggable loggableError"},"marshal":{"error":"OOPS"},"nil":null,"nilerror":null}`+"\n"; got != want {
+		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
+	}
+}
+func TestFieldsErrs(t *testing.T) {
+	var err error = nil
+	out := &bytes.Buffer{}
+	log := New(out)
+	log.Log().Fields(map[string]interface{}{
+		"errors": []error{errors.New("some error"), nil, err, loggableError{errors.New("loggable")}, errorObjectMarshalerImpl{fmt.Errorf("oops")}},
+	}).Msg("")
+	if got, want := decodeIfBinaryToString(out.Bytes()), `{"errors":["some error",null,null,{"message":"loggable loggableError"},{"error":"OOPS"}]}`+"\n"; got != want {
 		t.Errorf("invalid log output:\ngot:  %v\nwant: %v", got, want)
 	}
 }
@@ -809,7 +871,7 @@ func (l loggableError) MarshalZerologObject(e *Event) {
 	if l.error == nil {
 		return
 	}
-	e.Str("message", l.error.Error()+": loggableError")
+	e.Str("message", l.error.Error()+" loggableError")
 }
 
 type nonLoggable struct {
@@ -817,62 +879,6 @@ type nonLoggable struct {
 	how   int
 	what  string
 }
-
-func TestErrorMarshalFunc_None(t *testing.T) {
-	// test default behaviour
-	testErrorMarshalFunc(t, nil, []string{
-		"default",
-		`{"message":"msg"}`,
-		`{"error":"err","message":"msg"}`,
-		`{"error":{"message":"err: loggableError"},"message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":["foo","bar"],"message":"msg"}`,
-	})
-}
-func TestErrorMarshalFunc_AppendedString(t *testing.T) {
-	// test returning an appended string from ErrorMarshalFunc
-	testErrorMarshalFunc(t, func(err error) interface{} {
-		if err == nil {
-			return nil
-		}
-		return err.Error() + ": marshaled string"
-	}, []string{
-		"appended string",
-		`{"message":"msg"}`,
-		`{"error":"err: marshaled string","message":"msg"}`,
-		`{"error":"err: marshaled string","message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":["foo: marshaled string","bar: marshaled string"],"message":"msg"}`,
-	})
-}
-func TestErrorMarshalFunc_NilError(t *testing.T) {
-	// test returning an nil error from ErrorMarshalFunc
-	testErrorMarshalFunc(t, func(err error) interface{} {
-		return error(nil)
-	}, []string{
-		"nil error",
-		`{"message":"msg"}`,
-		`{"message":"msg"}`,
-		`{"message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":[null,null],"message":"msg"}`,
-	})
-}
-
-func TestErrorMarshalFunc_UntypedNil(t *testing.T) {
-	// test returning an untyped nil from ErrorMarshalFunc
-	testErrorMarshalFunc(t, func(err error) interface{} {
-		return nil
-	}, []string{
-		"untyped nil",
-		`{"message":"msg"}`,
-		`{"message":"msg"}`,
-		`{"message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":[null,null],"message":"msg"}`,
-	})
-}
-
 type wrappedError struct {
 	error
 	msg string
@@ -885,6 +891,81 @@ func (w wrappedError) Error() string {
 	return w.error.Error() + ": " + w.msg
 }
 
+func TestErrorMarshalFunc_Default(t *testing.T) {
+	// test default behaviour
+	testErrorMarshalFunc(t, nil, "default",
+		"",
+		"null",
+
+		`"zot"`,
+		`"zot"`,
+
+		`{"message":"log loggableError"}`,
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		`"foo","bar"`,
+	)
+}
+func TestErrorMarshalFunc_AppendedString(t *testing.T) {
+	// test returning an appended string from ErrorMarshalFunc
+	testErrorMarshalFunc(t, func(err error) interface{} {
+		if err == nil {
+			return nil
+		}
+		return err.Error() + ": marshaled"
+	}, "appended string",
+		"",
+		"null",
+
+		`"zot: marshaled"`,
+		`"zot: marshaled"`,
+
+		`"log: marshaled"`,
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		`"foo: marshaled","bar: marshaled"`,
+	)
+}
+func TestErrorMarshalFunc_NilError(t *testing.T) {
+	// test returning an nil error from ErrorMarshalFunc
+	testErrorMarshalFunc(t, func(err error) interface{} {
+		return error(nil)
+	}, "nil error",
+		"",
+		"null",
+
+		"",
+		"null",
+
+		"",
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		"null,null",
+	)
+}
+
+func TestErrorMarshalFunc_UntypedNil(t *testing.T) {
+	// test returning an untyped nil from ErrorMarshalFunc
+	testErrorMarshalFunc(t, func(err error) interface{} {
+		return nil
+	}, "untyped nil",
+		"",
+		"null",
+
+		"",
+		"null",
+
+		"",
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		"null,null",
+	)
+}
+
 func TestErrorMarshalFunc_WrappedError(t *testing.T) {
 	// test returning an wrapped error from ErrorMarshalFunc
 	testErrorMarshalFunc(t, func(err error) interface{} {
@@ -895,41 +976,56 @@ func TestErrorMarshalFunc_WrappedError(t *testing.T) {
 		} else {
 			return wrappedError{err, "addendum"}
 		}
-	}, []string{
-		"wrapped error",
-		`{"message":"msg"}`,
-		`{"error":"err: addendum","message":"msg"}`,
-		`{"error":"err: addendum","message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":["foo: addendum","bar: addendum"],"message":"msg"}`,
-	})
+	}, "wrapped error",
+		"",
+		"null",
+
+		`"zot: addendum"`,
+		`"zot: addendum"`,
+
+		`"log: addendum"`,
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		`"foo: addendum","bar: addendum"`,
+	)
 }
 
 func TestErrorMarshalFunc_LoggableType(t *testing.T) {
 	// test returning a loggable type from ErrorMarshalFunc
 	testErrorMarshalFunc(t, func(err error) interface{} {
 		return loggableError{err}
-	}, []string{
-		"loggable type",
-		`{"error":{},"message":"msg"}`,
-		`{"error":{"message":"err: loggableError"},"message":"msg"}`,
-		`{"error":{"message":"err: loggableError"},"message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":[{"message":"foo: loggableError"},{"message":"bar: loggableError"}],"message":"msg"}`,
-	})
+	}, "loggable type",
+		"{}",
+		"null",
+
+		`{"message":"zot loggableError"}`,
+		`{"message":"zot loggableError"}`,
+
+		`{"message":"log loggableError"}`,
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		`{"message":"foo loggableError"},{"message":"bar loggableError"}`,
+	)
 }
 func TestErrorMarshalFunc_String(t *testing.T) {
 	// test returning a string type from ErrorMarshalFunc
 	testErrorMarshalFunc(t, func(err error) interface{} {
 		return "i'm an err" // return just a string
-	}, []string{
-		"string type",
-		`{"error":"i'm an err","message":"msg"}`,
-		`{"error":"i'm an err","message":"msg"}`,
-		`{"error":"i'm an err","message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":["i'm an err","i'm an err"],"message":"msg"}`,
-	})
+	}, "string type",
+		`"i'm an err"`,
+		"null",
+
+		`"i'm an err"`,
+		`"i'm an err"`,
+
+		`"i'm an err"`,
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		`"i'm an err","i'm an err"`,
+	)
 }
 
 func TestErrorMarshalFunc_NonLoggableType(t *testing.T) {
@@ -939,17 +1035,59 @@ func TestErrorMarshalFunc_NonLoggableType(t *testing.T) {
 			return nil
 		}
 		return nonLoggable{where: "here", how: 42, what: err.Error()}
-	}, []string{
-		"non-loggable type",
-		`{"message":"msg"}`,
-		`{"error":{},"message":"msg"}`,
-		`{"error":{},"message":"msg"}`,
-		`{"errs":[],"message":"msg"}`,
-		`{"errs":[{},{}],"message":"msg"}`,
-	})
+	}, "non-loggable type",
+		"",
+		"null",
+
+		"{}",
+		"{}",
+
+		"{}",
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		"{},{}",
+	)
 }
 
-func testErrorMarshalFunc(t *testing.T, errFunc func(err error) interface{}, wants []string) {
+func TestErrorMarshalFunc_NilMarshal(t *testing.T) {
+	// test returning a nil from ErrorMarshalFunc
+	testErrorMarshalFunc(t, func(err error) interface{} {
+		var nilerr error = nil
+		return nilerr
+	}, "nil-marshal",
+		"",
+		"null",
+
+		"",
+		"null",
+
+		"",
+		`{"message":"log loggableError"}`,
+
+		"[]",
+		"null,null",
+	)
+}
+
+func testErrorMarshalFunc(t *testing.T,
+	errFunc func(err error) interface{},
+	testcase string,
+
+	whenNil string,
+	whenNilField string,
+
+	hasValue string,
+	hasValueField string,
+
+	whenLoggable string,
+	whenLoggableField string,
+
+	errsNilValue string,
+	errsValue string,
+) {
+	const suffix = `"message":"msg"}`
+
 	if errFunc != nil {
 		originalErrorMarshalFunc := ErrorMarshalFunc
 		defer func() {
@@ -959,58 +1097,97 @@ func testErrorMarshalFunc(t *testing.T, errFunc func(err error) interface{}, wan
 		ErrorMarshalFunc = errFunc
 	}
 
-	testcase := wants[0]
 	var err error
+	wantNil := `{`
+	if whenNil != "" {
+		wantNil = wantNil + `"error":` + whenNil + `,`
+	}
+	wantNil = wantNil + suffix
 
+	wantNilField := `{"err":` + whenNilField + `,` + suffix
 	err = nil
-	testContextErrorMarshalFunc(t, testcase+" / ctx.Err(nil)", wants[1], func(ctx Context) Context {
+	testContextErrorMarshalFunc(t, testcase+" / context.Err(nil)", wantNil, func(ctx Context) Context {
 		ctx = ctx.Err(err)
 		return ctx
 	})
-	testEventErrorMarshalFunc(t, testcase+" / e.Err(nil)", wants[1], func(e *Event) *Event {
+	testEventErrorMarshalFunc(t, testcase+" / event.Err(nil)", wantNil, func(e *Event) *Event {
 		e.Err(err)
 		return e
 	})
+	testFieldsErrorMarshalFunc(t, testcase+" / field.Err(nil)", wantNilField, func(e *Event) *Event {
+		e.Fields(map[string]interface{}{"err": err})
+		return e
+	})
 
-	err = errors.New("err")
-	testContextErrorMarshalFunc(t, testcase+" / ctx.Err(error)", wants[2], func(ctx Context) Context {
+	wantErr := `{`
+	if hasValue != "" {
+		wantErr = wantErr + `"error":` + hasValue + `,`
+	}
+	wantErr = wantErr + suffix
+	wantErrField := `{"err":` + hasValueField + `,` + suffix
+	err = errors.New("zot")
+	testContextErrorMarshalFunc(t, testcase+" / context.Err(error)", wantErr, func(ctx Context) Context {
 		ctx = ctx.Err(err)
 		return ctx
 	})
-	testEventErrorMarshalFunc(t, testcase+" / e.Err(error)", wants[2], func(e *Event) *Event {
+	testEventErrorMarshalFunc(t, testcase+" / event.Err(error)", wantErr, func(e *Event) *Event {
 		e.Err(err)
 		return e
 	})
+	testFieldsErrorMarshalFunc(t, testcase+" / field.Err(error)", wantErrField, func(e *Event) *Event {
+		e.Fields(map[string]interface{}{"err": err})
+		return e
+	})
 
-	err = loggableError{errors.New("err")}
-	testContextErrorMarshalFunc(t, testcase+" / ctx.Err(loggable)", wants[3], func(ctx Context) Context {
+	wantLoggable := `{`
+	if whenLoggable != "" {
+		wantLoggable = wantLoggable + `"error":` + whenLoggable + `,`
+	}
+	wantLoggable = wantLoggable + suffix
+	wantLoggableField := `{"err":` + whenLoggableField + `,` + suffix
+	err = loggableError{errors.New("log")}
+	testContextErrorMarshalFunc(t, testcase+" / context.Err(loggable)", wantLoggable, func(ctx Context) Context {
 		ctx = ctx.Err(err)
 		return ctx
 	})
-	testEventErrorMarshalFunc(t, testcase+" / e.Err(loggable)", wants[3], func(e *Event) *Event {
+	testEventErrorMarshalFunc(t, testcase+" / event.Err(loggable)", wantLoggable, func(e *Event) *Event {
 		e.Err(err)
 		return e
 	})
+	testFieldsErrorMarshalFunc(t, testcase+" / field.Err(loggable)", wantLoggableField, func(e *Event) *Event {
+		e.Fields(map[string]interface{}{"err": err})
+		return e
+	})
 
+	wantErrsNil := `{"errs":` + errsNilValue + `,` + suffix
 	var errs []error = nil
-	testContextErrorMarshalFunc(t, testcase+" / ctx.Errs(nil)", wants[4], func(ctx Context) Context {
+	testContextErrorMarshalFunc(t, testcase+" / context.Errs(nil)", wantErrsNil, func(ctx Context) Context {
 		ctx = ctx.Errs("errs", errs)
 		return ctx
 	})
-	testEventErrorMarshalFunc(t, testcase+" / e.Errs(nil)", wants[4], func(e *Event) *Event {
+	testEventErrorMarshalFunc(t, testcase+" / event.Errs(nil)", wantErrsNil, func(e *Event) *Event {
 		e.Errs("errs", errs)
 		return e
 	})
+	testFieldsErrorMarshalFunc(t, testcase+" / field.Errs(nil)", wantErrsNil, func(e *Event) *Event {
+		e.Fields(map[string]interface{}{"errs": errs})
+		return e
+	})
 
+	wantErrs := `{"errs":[` + errsValue + `],` + suffix
 	errs = []error{errors.New("foo"), errors.New("bar")}
-	testContextErrorMarshalFunc(t, testcase+" / ctx.Errs([])", wants[5], func(ctx Context) Context {
+	testContextErrorMarshalFunc(t, testcase+" / context.Errs([])", wantErrs, func(ctx Context) Context {
 		ctx = ctx.Errs("errs", []error{errors.New("foo"), errors.New("bar")})
 		return ctx
 	})
-	testEventErrorMarshalFunc(t, testcase+" / e.Errs([])", wants[5], func(e *Event) *Event {
+	testEventErrorMarshalFunc(t, testcase+" / event.Errs([])", wantErrs, func(e *Event) *Event {
 		e.Errs("errs", errs)
 		return e
 	})
+	testFieldsErrorMarshalFunc(t, testcase+" / field.Errs([])", wantErrs, func(e *Event) *Event {
+		e.Fields(map[string]interface{}{"errs": errs})
+		return e
+	})
 }
 
 func testEventErrorMarshalFunc(t *testing.T, testcase string, wants string, test func(e *Event) *Event) {
@@ -1022,6 +1199,15 @@ func testEventErrorMarshalFunc(t *testing.T, testcase string, wants string, test
 	}
 }
 
+func testFieldsErrorMarshalFunc(t *testing.T, testcase string, wants string, test func(e *Event) *Event) {
+	out := &bytes.Buffer{}
+	logger := New(out)
+	test(logger.Log()).Msg("msg")
+	if got, want := decodeIfBinaryToString(out.Bytes()), wants+"\n"; got != want {
+		t.Errorf("%s output:\ngot:  %v\nwant: %v", testcase, got, want)
+	}
+}
+
 func testContextErrorMarshalFunc(t *testing.T, testcase string, wants string, test func(ctx Context) Context) {
 	out := &bytes.Buffer{}
 	ctx := New(out).With()