jinzhu/copier

go get -u github.com/jinzhu/copier

import "github.com/jinzhu/copier"

type User struct {
	Name string
	Role string
	Age  int32
}

func (user *User) DoubleAge() int32 {
	return 2 * user.Age
}

type Employee struct {
	Name      string
	Age       int32
	DoubleAge int32
	SuperRole string
}

func (employee *Employee) Role(role string) {
	employee.SuperRole = "Super " + role
}

func main() {
	user := User{Name: "Jinzhu", Age: 18, Role: "Admin"}
	employee := Employee{}

	copier.Copy(&employee, &user)
	fmt.Printf("%#v\n", employee)
	// Output: Employee{Name:"Jinzhu", Age:18, DoubleAge:36, SuperRole:"Super Admin"}
}

type Source struct {
    Name   string
    Secret string // We do not want this to be copied.
}

type Target struct {
    Name   string
    Secret string `copier:"-"`
}

func main() {
    source := Source{Name: "John", Secret: "so_secret"}
    target := Target{}

    copier.Copy(&target, &source)
    fmt.Printf("Name: %s, Secret: '%s'\n", target.Name, target.Secret)
    // Output: Name: John, Secret: ''
}

type MandatorySource struct {
	Identification int
}

type MandatoryTarget struct {
	ID int `copier:"must"` // This field must be copied, or it will panic/error.
}

func main() {
	source := MandatorySource{}
	target := MandatoryTarget{ID: 10}

	// This will result in a panic or an error since ID is a must field but is empty in source.
	if err := copier.Copy(&target, &source); err != nil {
		log.Fatal(err)
	}
}

type SafeSource struct {
	ID string
}

type SafeTarget struct {
	Code string `copier:"must,nopanic"` // Enforce copying without panic.
}

func main() {
	source := SafeSource{}
	target := SafeTarget{Code: "200"}

	if err := copier.Copy(&target, &source); err != nil {
		log.Fatalln("Error:", err)
	}
	// This will not panic, but will return an error due to missing mandatory field.
}

type SourceWithNil struct {
    Details *string
}

type TargetOverride struct {
    Details *string `copier:"override"` // Even if source is nil, copy it.
}

func main() {
    details := "Important details"
    source := SourceWithNil{Details: nil}
    target := TargetOverride{Details: &details}

    copier.CopyWithOption(&target, &source, copier.Option{IgnoreEmpty: true})
    if target.Details == nil {
        fmt.Println("Details field was overridden to nil.")
    }
}

type SourceEmployee struct {
    Identifier int64
}

type TargetWorker struct {
    ID int64 `copier:"Identifier"` // Map Identifier from SourceEmployee to ID in TargetWorker
}

func main() {
    source := SourceEmployee{Identifier: 1001}
    target := TargetWorker{}

    copier.Copy(&target, &source)
    fmt.Printf("Worker ID: %d\n", target.ID)
    // Output: Worker ID: 1001
}

// Assuming User and Employee structs defined earlier with method and field respectively.

func main() {
    user := User{Name: "Jinzhu", Age: 18}
    employee := Employee{}

    copier.Copy(&employee, &user)
    fmt.Printf("DoubleAge: %d\n", employee.DoubleAge)
    // Output: DoubleAge: 36, demonstrating method to field copying.
}

func main() {
    user := User{Name: "Jinzhu", Age: 18, Role: "Admin"}
    var employees []Employee

    copier.Copy(&employees, &user)
    fmt.Printf("%#v\n", employees)
    // Output: []Employee{{Name: "Jinzhu", Age: 18, DoubleAge: 36, SuperRole: "Super Admin"}}
}

func main() {
    users := []User{{Name: "Jinzhu", Age: 18, Role: "Admin"}, {Name: "jinzhu 2", Age: 30, Role: "Dev"}}
    var employees []Employee

    copier.Copy(&employees, &users)
    fmt.Printf("%#v\n", employees)
    // Output: []Employee{{Name: "Jinzhu", Age: 18, DoubleAge: 36, SuperRole: "Super Admin"}, {Name: "jinzhu 2", Age: 30, DoubleAge: 60, SuperRole: "Super Dev"}}
}

func main() {
    map1 := map[int]int{3: 6, 4: 8}
    map2 := map[int32]int8{}

    copier.Copy(&map2, map1)
    fmt.Printf("%#v\n", map2)
    // Output: map[int32]int8{3:6, 4:8}
}

package main

import (
	"fmt"
	"github.com/jinzhu/copier"
)

type Address struct {
	City    string
	Country string
}

type Contact struct {
	Email  string
	Phones []string
}

type Employee struct {
	Name      string
	Age       int32
	Addresses []Address
	Contact   *Contact
}

type Manager struct {
	Name            string `copier:"must"`
	Age             int32  `copier:"must,nopanic"`
	ManagedCities   []string
	Contact         *Contact `copier:"override"`
	SecondaryEmails []string
}

func main() {
	employee := Employee{
		Name: "John Doe",
		Age:  30,
		Addresses: []Address{
			{City: "New York", Country: "USA"},
			{City: "San Francisco", Country: "USA"},
		},
		Contact: nil,
	}

	manager := Manager{
		ManagedCities: []string{"Los Angeles", "Boston"},
		Contact: &Contact{
			Email:  "[email protected]",
			Phones: []string{"123-456-7890", "098-765-4321"},
		}, // since override is set this should be overridden with nil
		SecondaryEmails: []string{"[email protected]"},
	}

	copier.CopyWithOption(&manager, &employee, copier.Option{IgnoreEmpty: true, DeepCopy: true})

	fmt.Printf("Manager: %#v\n", manager)
	// Output: Manager struct showcasing copied fields from Employee,
	// including overridden and deeply copied nested slices.
}