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Package for fast copying structs of different types

License: Apache License 2.0

Makefile 1.09% Go 98.91%

golang go golang-library golang-package performance copy deepcopy

copy's Introduction

Package for fast copying structs of different types

This package is meant to make copying of structs to/from others structs a bit easier.

Nested structures, embedded types, pointers, sql null types are supported.

Installation

go get -u github.com/gotidy/copy

Example

type Person struct {
    Name       string
    MiddleName *string
    Surname    string
}

type User struct {
    Person
    Email   string
    Age     int8
    Married bool
}

type Employee struct {
    Name       string
    MiddleName string
    Surname    string
    Email      string
    Age        int
}

src := User{
    Person: Person{
        Name:       "John",
        MiddleName: nil,
        Surname:    "Smith",
    },
    Email:   "[email protected]",
    Age:     33,
    Married: false,
}
dst := Employee{}

copiers := copy.New() // New("json")
copiers.Copy(&dst, &src)

// Or more fast use case is to create the type specific copier.

copier := copiers.Get(&Employee{}, &User{}) // Created once for a pair of types.
copier.Copy(&dst, &src)

Alternative projects

Benchmark

Benchmarks source code can be found here

go test -bench=. -benchmem ./...
goos: darwin
goarch: amd64
pkg: github.com/gotidy/copy-bench
BenchmarkManualCopy-12         177310519         6.92 ns/op          0 B/op        0 allocs/op
BenchmarkCopiers-12             13476417         84.1 ns/op          0 B/op        0 allocs/op
BenchmarkCopier-12              40226689         27.5 ns/op          0 B/op        0 allocs/op
BenchmarkJinzhuCopier-12          407480         2711 ns/op       2480 B/op       34 allocs/op
BenchmarkDeepcopier-12            262836         4346 ns/op       4032 B/op       73 allocs/op
PASS
ok      github.com/gotidy/copy-bench    6.922s

See the documentation for more information.

License

Apache 2.0

copy's People

Contributors

Stargazers

Watchers

Forkers

frederikhors standardgalactic huangweiboy2 holynnchen

copy's Issues

Copy function does not appear to deep copy

If you have the following structs:

type User struct {
    Name string
    Email string
    Company *Company
}

type Company struct {
    Name string
    Domain string
}

and do the following:

user1 := &User{
    Name: "Someone",
    Email: "[email protected]",
    Company: &Company{
        Name: "Some co.",
        Domain: "example.com"
   },
}

var user2 User
copy.Copy(&user2, user1)

The pointer contained in user1 is copied to user2. If I now do user2.Company.Name = "Something else", the value is also changed in user1.
Is this intended? In that case, your library is not intended for use as a deep copier? It may be nice to offer the option whether to deepcopy or not as a parameter.

Thanks for all the work you put in this library!

Congratulations and question!

Congratulations for this project! This is amazing!

I'll use it ASAP.

I'm new to Golang.

I saw the bench, what's the difference between these two?

func BenchmarkCopiers(b *testing.B) {
	b.StopTimer()
	c := copy.New()
	c.Prepare(&dst, &src)
	b.StartTimer()

	for i := 0; i < b.N; i++ {
		c.Copy(&dst, &src)
	}
}

func BenchmarkCopier(b *testing.B) {
	b.StopTimer()
	c := copy.New()
	copier := c.Get(&dst, &src)
	b.StartTimer()

	for i := 0; i < b.N; i++ {
		copier.Copy(&dst, &src)
	}
}

Can't we "simply" always use the fastest? What changes?

Thanks and again CONGRATULATIONS!

Nested slices of different type

I have this situation:

type Player struct {
	Firstname  string
	Username *string
	UserDetail *UserDetail
}

type PlayerInput struct {
	Firstname     *string          `json:"firstname"`
	Username      *string          `json:"username"`
	UserDetail *UserDetailInput    `json:"UserDetail"`
}

type UserDetail struct {
	EmailAddresses    []EmailAddress    `json:"emailAddresses"`
}

type UserDetailInput struct {
	EmailAddresses    []EmailAddressInput    `json:"emailAddresses"`
}

type EmailAddress struct {
	Address *string `json:"address"`
}

type EmailAddressInput struct {
	Address *string `json:"address"`
}

func fromTo(input *models.PlayerInput, output *models.Player) {
	c := copy.New()
	c.Get(output, input).Copy(output, input)
}

I get this error:

field «EmailAddresses» of type «[]models.EmailAddressInput» is not assignable to field «EmailAddresses» of type «[]models.EmailAddress»

Do you think I'm wrong?

Is there any way to fix?

Return error instead of causing panics

It's bad practice to cause panics in a library.
Recover inside your package and return an error If you must use panics.

How to copy only not null fields?

Is there a way to copy only the not null fields?

Example:

package main

import (
	"fmt"

	"github.com/gotidy/copy"
)

type Player struct {
	Firstname  string
	Username   *string
	UserDetail *UserDetail
}

type PlayerInput struct {
	Firstname  *string
	Username   *string
	UserDetail *UserDetail
}

type UserDetail struct {
	Email *string
}

func main() {
	inputFirstname := "Bob"

	input := PlayerInput{
		Firstname: &inputFirstname,
	}

	outputUsername := "BobTheBob"

	output := Player{
		Username: &outputUsername,
	}

	c := copy.New()
	c.Get(&output, &input).Copy(&output, &input)

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

I get:

main.Player{Firstname:"Bob", Username:(*string)(nil), UserDetail:(*main.UserDetail)(nil)}

I would:

main.Player{Firstname:"Bob", Username:"BobTheBob", UserDetail:(*main.UserDetail)(nil)}

Is this possible?

gotidy / copy Goto Github PK

copy's Introduction

Package for fast copying structs of different types

Installation

Example

Alternative projects

License

copy's People

Contributors

Stargazers

Watchers

Forkers

copy's Issues

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