Add defaults value function

go.mod

@@ -43,6 +43,7 @@ require (
 	github.com/bxcodec/faker/v3 v3.6.0 // indirect
 	github.com/coreos/go-semver v0.3.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d // indirect
+	github.com/creasty/defaults v1.5.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/davidlazar/go-crypto v0.0.0-20190912175916-7055855a373f // indirect
 	github.com/gin-contrib/sse v0.1.0 // indirect

go.sum

@@ -97,6 +97,8 @@ github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSY
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/creasty/defaults v1.5.2 h1:/VfB6uxpyp6h0fr7SPp7n8WJBoV8jfxQXPCnkVSjyls=
+github.com/creasty/defaults v1.5.2/go.mod h1:FPZ+Y0WNrbqOVw+c6av63eyHUAl6pMHZwqLPvXUZGfY=
 github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=

tool/defaults.go

+package tool
+
+import (
+	"github.com/creasty/defaults"
+)
+
+var (
+	Default     = defaults.Set
+	MustDefault = defaults.MustSet
+)

tool/defaults_test.go

+package tool
+
+import (
+	"math/rand"
+	"testing"
+
+	"github.com/creasty/defaults"
+	"github.com/stretchr/testify/assert"
+)
+
+type Gender string
+
+type Sample struct {
+	Name   string `default:"John Smith"`
+	Age    int    `default:"27"`
+	Gender Gender `default:"m"`
+
+	Slice       []string       `default:"[]"`
+	SliceByJSON []int          `default:"[1, 2, 3]"` // Supports JSON
+	Map         map[string]int `default:"{}"`
+	MapByJSON   map[string]int `default:"{\"foo\": 123}"`
+
+	Struct    OtherStruct  `default:"{}"`
+	StructPtr *OtherStruct `default:"{\"Foo\": 123}"`
+
+	NoTag  OtherStruct // Recurses into a nested struct by default
+	OptOut OtherStruct `default:"-"` // Opt-out
+}
+
+type OtherStruct struct {
+	Hello  string `default:"world"` // Tags in a nested struct also work
+	Foo    int    `default:"-"`
+	Random int    `default:"-"`
+}
+
+// SetDefaults implements defaults.Setter interface
+func (s *OtherStruct) SetDefaults() {
+	if defaults.CanUpdate(s.Random) { // Check if it's a zero value (recommended)
+		s.Random = rand.Int() // Set a dynamic value
+	}
+}
+
+func TestDefaults(t *testing.T) {
+	obj := &Sample{}
+	err := Default(obj)
+	assert.Nil(t, err)
+	assert.Equal(t, obj.Age, 27)
+	assert.Equal(t, obj.Gender, Gender("m"))
+	assert.Equal(t, obj.Slice, []string{})
+	assert.Equal(t, obj.Map, map[string]int{})
+	assert.Equal(t, obj.MapByJSON, map[string]int{"foo": 123})
+}

tool/tool.go

@@ -36,8 +36,10 @@ func Exist(path string) bool {
 	return false
 }
 
-//https://github.com/fatih/gomodifytags
-//https://github.com/favadi/protoc-go-inject-tag
-//https://github.com/0xAX/go-algorithms
-//https://github.com/emirpasic/gods
-//
+// https://github.com/fatih/gomodifytags
+// https://github.com/favadi/protoc-go-inject-tag
+// https://github.com/0xAX/go-algorithms
+// https://github.com/emirpasic/gods
+// https://github.com/gookit/goutil
+// https://github.com/gookit/color
+// https://github.com/creasty/defaults