Update an existing instance

When you already have an existing instance to a struct and want to update a couple of fields from a different type, then you can use update ARG to instruct goverter to create a conversion that updates an instance passed as argument.

input.go

package update

// goverter:converter
type Converter interface {
	// goverter:update target
	Convert(source Input, target *Output)
}

type Input struct {
	Name    *string
	Aliases []string
	Age     int
}

type Output struct {
	Name    *string
	Aliases []string
	Age     int
}

generated/generated.go

// Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
//go:build !goverter

package generated

import update "github.com/jmattheis/goverter/example/update"

type ConverterImpl struct{}

func (c *ConverterImpl) Convert(source update.Input, target *update.Output) {
	if source.Name != nil {
		xstring := *source.Name
		target.Name = &xstring
	}
	if source.Aliases != nil {
		target.Aliases = make([]string, len(source.Aliases))
		for i := 0; i < len(source.Aliases); i++ {
			target.Aliases[i] = source.Aliases[i]
		}
	}
	target.Age = source.Age
}

Don't override zero values

If you have fields that aren't pointers, then you may want to enable update:ignoreZeroValueField to skip overriding those with the unset values.

input.go

package update

// goverter:converter
// goverter:update:ignoreZeroValueField
// ^- this setting can be specified on the conversion method
type WithIgnore interface {
	// goverter:update target
	Convert(source Input, target *Output)
}

// goverter:converter
type WithoutIgnore interface {
	// goverter:update target
	Convert(source Input, target *Output)
}

type Input struct {
	Name    string
	Age     int
	Cool    bool
	Address *string
}

type Output struct {
	Name    string
	Age     int
	Cool    bool
	Address *string
}

generated/generated.go

// Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
//go:build !goverter

package generated

import updateignorezero "github.com/jmattheis/goverter/example/update-ignore-zero"

type WithIgnoreImpl struct{}

func (c *WithIgnoreImpl) Convert(source updateignorezero.Input, target *updateignorezero.Output) {
	if source.Name != "" {
		target.Name = source.Name
	}
	if source.Age != 0 {
		target.Age = source.Age
	}
	if source.Cool != false {
		target.Cool = source.Cool
	}
	if source.Address != nil {
		xstring := *source.Address
		target.Address = &xstring
	}
}

type WithoutIgnoreImpl struct{}

func (c *WithoutIgnoreImpl) Convert(source updateignorezero.Input, target *updateignorezero.Output) {
	target.Name = source.Name
	target.Age = source.Age
	target.Cool = source.Cool
	if source.Address != nil {
		xstring := *source.Address
		target.Address = &xstring
	}
}