map

Example: Manual

The manual example uses manual mapping to match three models.

./domain/domain.go

// Package domain contains business logic models.
package domain

// Account represents a user account.
type Account struct {
	ID       string
	Name     string
	Email    string
	Password string // The password field will not be copied.
	Other    string // The other field is not used.
}

./models/model.go

// Package models contains data storage models (i.e database).
package models

// Account represents the data model for account.
type Account struct {
	ID       int
	Name     string
	Email    string
	Password string
}

// A User represents the data model for a user.
type User struct {
	UserID   int
	Name     string
	UserData string
}

YML

# Define where the code will be generated.
generated:
  setup: ./setup.go
  output: ../copygen.go

# Templates and custom options aren't used for this example.

Go

Map the from-field models.User.UserID to to-fields with the regex pattern domain.Account.ID. Map the from-field models.Account.Name to to-fields with the regex pattern domain.Account.Name. Map the from-field models.Account.Email to to-fields with the regex pattern domain.Account.Email.

// Copygen defines the functions that will be generated.
type Copygen interface {
	// map models.User.UserID domain.Account.ID
	// map models.Account.Name domain.Account.Name
	// map models.Account.Email domain.Account.Email
	ModelsToDomain(*models.Account, *models.User) *domain.Account
}

/* Define the function and field this converter is applied to using regex. */
// convert .* models.User.UserID
// Itoa converts an integer to an ascii value.
func Itoa(i int) string {
	return c.Itoa(i)
}

Use pointers to avoid allocations.

Output

copygen -yml path/to/yml

// Code generated by github.com/switchupcb/copygen
// DO NOT EDIT.

// Package copygen contains the setup information for copygen generated code.
package copygen

import (
	c "strconv"

	"github.com/switchupcb/copygen/examples/map/domain"
	"github.com/switchupcb/copygen/examples/map/models"
)

/* Define the function and field this converter is applied to using regex. */
// Itoa converts an integer to an ascii value.
func Itoa(i int) string {
	return c.Itoa(i)
}

// ModelsToDomain copies a *models.Account, *models.User to a *domain.Account.
func ModelsToDomain(tA *domain.Account, fA *models.Account, fU *models.User) {
	// *domain.Account fields
	tA.ID = Itoa(fU.UserID)
	tA.Name = fA.Name
	tA.Email = fA.Email
}