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https://github.com/jinzhu/copier

Copier for golang, copy value from struct to struct and more
https://github.com/jinzhu/copier

copy go golang golang-package

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Copier for golang, copy value from struct to struct and more

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# Copier



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



[![test status](https://github.com/jinzhu/copier/workflows/tests/badge.svg?branch=master "test status")](https://github.com/jinzhu/copier/actions)



## Features



* Copy from field to field with same name

* Copy from method to field with same name

* Copy from field to method with same name

* Copy from slice to slice

* Copy from struct to slice

* Copy from map to map

* Enforce copying a field with a tag

* Ignore a field with a tag

* Deep Copy



## Usage



```go

package main



import (

	"fmt"

	"github.com/jinzhu/copier"

)



type User struct {

	Name        string

	Role        string

	Age         int32

	EmployeeCode int64 `copier:"EmployeeNum"` // specify field name



	// Explicitly ignored in the destination struct.

	Salary   int

}



func (user *User) DoubleAge() int32 {

	return 2 * user.Age

}



// Tags in the destination Struct provide instructions to copier.Copy to ignore

// or enforce copying and to panic or return an error if a field was not copied.

type Employee struct {

	// Tell copier.Copy to panic if this field is not copied.

	Name      string `copier:"must"`



	// Tell copier.Copy to return an error if this field is not copied.

	Age       int32  `copier:"must,nopanic"`



	// Tell copier.Copy to explicitly ignore copying this field.

	Salary    int    `copier:"-"`



	DoubleAge int32

	EmployeeId int64 `copier:"EmployeeNum"` // specify field name

	SuperRole string

}



func (employee *Employee) Role(role string) {

	employee.SuperRole = "Super " + role

}



func main() {

	var (

		user      = User{Name: "Jinzhu", Age: 18, Role: "Admin", Salary: 200000}

		users     = []User{{Name: "Jinzhu", Age: 18, Role: "Admin", Salary: 100000}, {Name: "jinzhu 2", Age: 30, Role: "Dev", Salary: 60000}}

		employee  = Employee{Salary: 150000}

		employees = []Employee{}

	)



	copier.Copy(&employee, &user)



	fmt.Printf("%#v \n", employee)

	// Employee{

	//    Name: "Jinzhu",           // Copy from field

	//    Age: 18,                  // Copy from field

	//    Salary:150000,            // Copying explicitly ignored

	//    DoubleAge: 36,            // Copy from method

	//    EmployeeId: 0,            // Ignored

	//    SuperRole: "Super Admin", // Copy to method

	// }



	// Copy struct to slice

	copier.Copy(&employees, &user)



	fmt.Printf("%#v \n", employees)

	// []Employee{

	//   {Name: "Jinzhu", Age: 18, Salary:0, DoubleAge: 36, EmployeeId: 0, SuperRole: "Super Admin"}

	// }



	// Copy slice to slice

	employees = []Employee{}

	copier.Copy(&employees, &users)



	fmt.Printf("%#v \n", employees)

	// []Employee{

	//   {Name: "Jinzhu", Age: 18, Salary:0, DoubleAge: 36, EmployeeId: 0, SuperRole: "Super Admin"},

	//   {Name: "jinzhu 2", Age: 30, Salary:0, DoubleAge: 60, EmployeeId: 0, SuperRole: "Super Dev"},

	// }



 	// Copy map to map

	map1 := map[int]int{3: 6, 4: 8}

	map2 := map[int32]int8{}

	copier.Copy(&map2, map1)



	fmt.Printf("%#v \n", map2)

	// map[int32]int8{3:6, 4:8}

}

```



### Copy with Option



```go

copier.CopyWithOption(&to, &from, copier.Option{IgnoreEmpty: true, DeepCopy: true})

```



## Contributing



You can help to make the project better, check out [http://gorm.io/contribute.html](http://gorm.io/contribute.html) for things you can do.



# Author



**jinzhu**



* 

* 

* 



## License



Released under the [MIT License](https://github.com/jinzhu/copier/blob/master/License).