✨ feat(dump): support skip nil field dump on map, struct by option Sk…

…ipNilField

close #41

dump/README.md

@@ -61,6 +61,40 @@ You will see:
 
 ![](_examples/preview-nested-struct.png)
 
+### Options for dump
+
+```go
+// Options for dumper
+type Options struct {
+	// Output the output writer
+	Output io.Writer
+	// NoType don't show data type TODO
+	NoType bool
+	// NoColor don't with color
+	NoColor bool
+	// IndentLen width. default is 2
+	IndentLen int
+	// IndentChar default is one space
+	IndentChar byte
+	// MaxDepth for nested print
+	MaxDepth int
+	// ShowFlag for display caller position
+	ShowFlag int
+	// CallerSkip skip for call runtime.Caller()
+	CallerSkip int
+	// ColorTheme for print result.
+	ColorTheme Theme
+	// SkipNilField value dump on map, struct.
+	SkipNilField bool
+	// SkipPrivate field dump on struct.
+	SkipPrivate bool
+	// BytesAsString dump handle.
+	BytesAsString bool
+	// MoreLenNL array/slice elements length > MoreLenNL, will wrap new line
+	// MoreLenNL int
+}
+```
+
 ## Functions API
 
 ```go

dump/dump.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"io"
 	"os"
+	"reflect"
 
 	"github.com/gookit/color"
 )
@@ -130,3 +131,16 @@ func Clear(vs ...any) {
 func isUnexported(fieldName string) bool {
 	return fieldName[0] < 'A' || fieldName[0] > 'Z'
 }
+
+func isNilOrInvalid(v reflect.Value) bool {
+	if !v.IsValid() {
+		return true
+	}
+
+	switch v.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Map, reflect.Pointer, reflect.UnsafePointer, reflect.Interface, reflect.Slice:
+		return v.IsNil()
+	default:
+		return false
+	}
+}

dump/dump_test.go

@@ -308,6 +308,28 @@ func TestStruct_ptrField(t *testing.T) {
 	color.Infoln("\nUse fmt.Println:")
 	fmt.Println(opt)
 	fmt.Println("---------------------------------------------------------------")
+
+	opt = &userOpts{
+		Str: &astr,
+	}
+
+	Println(opt)
+	/* Output:
+	PRINT AT github.com/gookit/goutil/dump.TestStruct_ptrField(dump_test.go:316)
+	&dump.userOpts {
+	  Int: *int<nil>,
+	  Str: &string("xyz"), #len=3
+	},
+	*/
+	d := newStd().WithOptions(SkipNilField())
+	d.Println(opt)
+	/* Output:
+	PRINT AT github.com/gookit/goutil/dump.TestStruct_ptrField(dump_test.go:318)
+	&dump.userOpts {
+	    Str: &string("xyz"), #len=3
+	  },
+
+	*/
 }
 
 func TestFormat(t *testing.T) {

dump/dumper.go

@@ -274,16 +274,17 @@ func (d *Dumper) printRValue(t reflect.Type, v reflect.Value) {
 
 		fldNum := v.NumField()
 		for i := 0; i < fldNum; i++ {
-			fv := v.Field(i)
-			d.advance(1)
-
 			fName := t.Field(i).Name
 			if d.SkipPrivate && isUnexported(fName) {
 				continue
 			}
 
-			// if d.SkipNilField { // TODO
-			// }
+			fv := v.Field(i)
+			if d.SkipNilField && isNilOrInvalid(fv) {
+				continue
+			}
+
+			d.advance(1)
 
 			// print field name
 			d.indentPrint(d.ColorTheme.field(fName), ": ")
@@ -303,10 +304,11 @@ func (d *Dumper) printRValue(t reflect.Type, v reflect.Value) {
 
 		for _, key := range v.MapKeys() {
 			mv := v.MapIndex(key)
-			d.advance(1)
+			if d.SkipNilField && isNilOrInvalid(mv) {
+				continue
+			}
 
-			// if d.SkipNilField { // TODO
-			// }
+			d.advance(1)
 
 			// print key name
 			if !key.CanInterface() {

dump/dumper_test.go

@@ -204,6 +204,9 @@ func TestDumper_AccessCantExportedField1(t *testing.T) {
 	}
 
 	Println(myS1)
+
+	d := newStd().WithOptions(SkipPrivate())
+	d.Println(myS1)
 }
 
 // ------------------------- map -------------------------
@@ -355,7 +358,7 @@ var (
 )
 
 func TestDump_Struct(t *testing.T) {
-
+	P(user)
 }
 
 func TestStruct_WithNested(t *testing.T) {

dump/options_test.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"testing"
 
+	"github.com/gookit/color"
 	"github.com/gookit/goutil/testutil/assert"
 )
 
@@ -25,7 +26,38 @@ func TestSkipPrivate(t *testing.T) {
 	assert.NotContains(t, str, "id: string(\"ab12345\")")
 }
 
+// see https://github.com/gookit/goutil/issues/41
+func TestSkipNilField(t *testing.T) {
+	buf := newBuffer()
+	dumper := newStd().WithOptions(WithoutOutput(buf), WithoutPosition(), WithoutColor())
+	assert.False(t, dumper.SkipNilField)
+
+	mp := map[string]any{
+		"name": "inhere",
+		"age":  nil,
+	}
+
+	dumper.Println(mp)
+	str := buf.String()
+	fmt.Print("Default: \n", str)
+	assert.StrContains(t, str, `"age": nil`)
+	buf.Reset()
+
+	dumper.WithOptions(SkipNilField())
+	assert.True(t, dumper.SkipNilField)
+	dumper.Println(mp)
+
+	str = buf.String()
+	fmt.Print("SkipNilField: \n", str)
+	assert.NotContains(t, str, `"age": nil`)
+}
+
 func TestWithoutColor(t *testing.T) {
+	ol := color.ForceColor()
+	defer func() {
+		color.ForceSetColorLevel(ol)
+	}()
+
 	buf := newBuffer()
 	dumper := newStd().WithOptions(WithoutOutput(buf), WithoutPosition(), WithCallerSkip(2))