Copier

I am a copier, I copy everything from one to another

Copier是golang实现的，实现不同数据结构之间数据复制的工具包

github地址

使用方法

以User和Employee之间相互复制为例
使用的版本为 v0.3.5

入门

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}var employee = Employee{}// 从user把数据复制到employee中err := copier.Copy(&employee, user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Name:"Jinzhu", Age:18, Salary:200000}

toValue 传参必须为指针

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}// 正确用法// err := copier.Copy(&employee, user)err := copier.Copy(employee, user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// copy destination is invalid

结构体之间相互复制，默认以字段名作为映射

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}
// 结果：main.Employee{Name:"Jinzhu", Age:18, Salary:200000}

如果字段名不相同，则不会进行字段值复制，但是不会影响其他字段值复制

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  stringAge    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// 结果：main.Employee{Title:"", Age:18, Salary:200000}

如果字段名不相同的字段值想进行复制，可以通过标签进行映射

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  string `copier:"Name"`Age    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// 结果：main.Employee{Title:"Jinzhu", Age:18, Salary:200000}

copier 标签字段名必须是首字母大写

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  string `copier:"name"`Age    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// copier field name tag must be start upper case

相互映射的字段，数据类型要尽量相同，否则会出现意想不到的结果

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  int `copier:"Name"`Age    stringSalary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Title:0, Age:"\x12", Salary:200000}

支持通过同样的名字实现method给field赋值

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}func (receiver User) Title() string {return "Golang " + receiver.Name
}type Employee struct {Title  stringAge    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// User.Title() 给 Employee.Title 赋值
// main.Employee{Title:"Golang Jinzhu", Age:18, Salary:200000}

支持通过同样的名字实现field给method赋值

method必须有唯一的形参，形参的数据类型跟field要一致

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  stringAge    int32Salary int
}// 复制失败
//func (receiver *Employee) Name(name string, age int) {
//	receiver.Title = "Title " + name
//}// 复制失败
//func (receiver *Employee) Name() {
//	receiver.Title = "Title " + name
//}func (receiver *Employee) Name(name string) {receiver.Title = "Title " + name
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Title:"Title Jinzhu", Age:18, Salary:200000}

must 标签

must 标签用来指定toValue.field 必须有相应的 fromValue.field ，否则会报错

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  string `copier:"must"`Age    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// panic: Field Title has must tag but was not copied

忽略指定字段

通过标签 copier:"-"来标识字段要跳过字段值复制，而且只有标识在toValue字段上才会生效

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   string `copier:"-"`Age    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Name:"", Age:18, Salary:200000}

nopanic 标签

nopanic 用来告诉copier ，指定字段出现异常，通过返回error方式报错，而不是通过panic方式报错

当前的版本，源代码在返回error后，并没有对外抛出，所以当前的效果是，不抛panic，也不返回error

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Title  string `copier:"must,nopanic"`Age    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}employee := Employee{}err := copier.Copy(&employee, &user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Title:"", Age:18, Salary:200000}

结构体批量复制

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {users := []User{{Name:   "Jinzhu",Age:    18,Salary: 200000,},{Name:   "Jinzhu1",Age:    20,Salary: 180000,},}var employee []Employeeerr := copier.Copy(&employee, users)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// []main.Employee{main.Employee{Name:"Jinzhu", Age:18, Salary:200000}, main.Employee{Name:"Jinzhu1", Age:20, Salary:180000}}

结构体复制到结构体列表

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {users := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}var employee []Employeeerr := copier.Copy(&employee, users)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// []main.Employee{main.Employee{Name:"Jinzhu", Age:18, Salary:200000}}

map To map 复制

package mainimport ("fmt""github.com/jinzhu/copier"
)func main() {user := map[string]interface{}{"name":   "Jinzhu","age":    18,"salary": 200000,}var employee = map[string]interface{}{}err := copier.Copy(&employee, user)if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// map[string]interface {}{"age":18, "name":"Jinzhu", "salary":200000}

CopyWithOption 使用

CopyWithOption 支持调用时传参选择项，来影响copier的行为

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {user := User{Name:   "Jinzhu",Age:    18,Salary: 200000,}var employee = Employee{Name: "Jinzhu-Name",}err := copier.CopyWithOption(&employee, user, copier.Option{})if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Name:"Jinzhu", Age:18, Salary:200000}

IgnoreEmpty选项

IgnoreEmpty 选项用来指定是否跳过空值

package mainimport ("fmt""github.com/jinzhu/copier"
)type User struct {Name   stringAge    int32Salary int
}type Employee struct {Name   stringAge    int32Salary int
}func main() {user := User{Name:   "",Age:    18,Salary: 200000,}var employee = Employee{Name: "Jinzhu-Name",}err := copier.CopyWithOption(&employee, user, copier.Option{IgnoreEmpty: true})if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", employee)}
}// main.Employee{Name:"Jinzhu-Name", Age:18, Salary:200000}

Converters 选项

Converters 选项用来自定义转换方式

package mainimport ("fmt""github.com/jinzhu/copier""time"
)type User struct {Name     stringAge      int32Salary   intBirthday time.Time
}type Employee struct {Name     stringAge      int32Salary   intBirthday string
}func main() {user := User{Name:     "Jinzhu",Age:      18,Salary:   200000,Birthday: time.Now(),}var employee = Employee{Name: "Jinzhu-Name",}err := copier.CopyWithOption(&employee, user, copier.Option{IgnoreEmpty: true, Converters: []copier.TypeConverter{{SrcType: time.Time{},DstType: "",Fn: func(src interface{}) (interface{}, error) {srcTime, ok := src.(time.Time)if !ok {return "", nil}return srcTime.Format("2006-01-02 15:04:05"), nil},},}})if err != nil {fmt.Println(err)} else {fmt.Printf("%#v \n", user)fmt.Printf("%#v \n", employee)}
}// main.User{Name:"Jinzhu", Age:18, Salary:200000, Birthday:time.Date(2023, time.November, 12, 20, 48, 47, 73860000, time.Local)}
// main.Employee{Name:"Jinzhu", Age:18, Salary:200000, Birthday:"2023-11-12 20:48:47"}

DeepCopy 选项

待补充

总结

整体来说，copier能满足我们日常业务开发中的大部分场景，而且可以有效的解耦数据结构之间的依赖，通过一种低耦合的方式，实现数据复制任务

附：本文只是简单总结了copier的使用方式，不足之处希望能多多提意见

——结束