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https://github.com/ulule/deepcopier

simple struct copying for golang
https://github.com/ulule/deepcopier

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simple struct copying for golang

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# Deepcopier



[![Build Status](https://secure.travis-ci.org/ulule/deepcopier.svg?branch=master)](http://travis-ci.org/ulule/deepcopier)



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



## Installation



```bash

go get -u github.com/ulule/deepcopier

```



## Usage



```golang

// Deep copy instance1 into instance2

Copy(instance1).To(instance2)



// Deep copy instance1 into instance2 and passes the following context (which

// is basically a map[string]interface{}) as first argument

// to methods of instance2 that defined the struct tag "context".

Copy(instance1).WithContext(map[string]interface{}{"foo": "bar"}).To(instance2)



// Deep copy instance2 into instance1

Copy(instance1).From(instance2)



// Deep copy instance2 into instance1 and passes the following context (which

// is basically a map[string]interface{}) as first argument

// to methods of instance1 that defined the struct tag "context".

Copy(instance1).WithContext(map[string]interface{}{"foo": "bar"}).From(instance2)

```



Available options for `deepcopier` struct tag:



| Option    | Description                                                          |

| --------- | -------------------------------------------------------------------- |

| `field`   | Field or method name in source instance                              |

| `skip`    | Ignores the field                                                    |

| `context` | Takes a `map[string]interface{}` as first argument (for methods)     |

| `force`   | Set the value of a `sql.Null*` field (instead of copying the struct) |



**Options example:**



```golang

type Source struct {

    Name                         string

    SkipMe                       string

    SQLNullStringToSQLNullString sql.NullString

    SQLNullStringToString        sql.NullString



}



func (Source) MethodThatTakesContext(c map[string]interface{}) string {

    return "whatever"

}



type Destination struct {

    FieldWithAnotherNameInSource      string         `deepcopier:"field:Name"`

    SkipMe                            string         `deepcopier:"skip"`

    MethodThatTakesContext            string         `deepcopier:"context"`

    SQLNullStringToSQLNullString      sql.NullString 

    SQLNullStringToString             string         `deepcopier:"force"`

}



```



Example:



```golang

package main



import (

    "fmt"

 

    "github.com/ulule/deepcopier"

)



// Model

type User struct {

    // Basic string field

    Name  string

    // Deepcopier supports https://golang.org/pkg/database/sql/driver/#Valuer

    Email sql.NullString

}



func (u *User) MethodThatTakesContext(ctx map[string]interface{}) string {

    // do whatever you want

    return "hello from this method"

}



// Resource

type UserResource struct {

    DisplayName            string `deepcopier:"field:Name"`

    SkipMe                 string `deepcopier:"skip"`

    MethodThatTakesContext string `deepcopier:"context"`

    Email                  string `deepcopier:"force"`



}



func main() {

    user := &User{

        Name: "gilles",

        Email: sql.NullString{

            Valid: true,

            String: "[email protected]",

        },

    }



    resource := &UserResource{}



    deepcopier.Copy(user).To(resource)



    fmt.Println(resource.DisplayName)

    fmt.Println(resource.Email)

}

```



Looking for more information about the usage?



We wrote [an introduction article](https://github.com/ulule/deepcopier/blob/master/examples/rest-usage/README.rst).

Have a look and feel free to give us your feedback.



## Contributing



* Ping us on twitter [@oibafsellig](https://twitter.com/oibafsellig), [@thoas](https://twitter.com/thoas)

* Fork the [project](https://github.com/ulule/deepcopier)

* Help us improving and fixing [issues](https://github.com/ulule/deepcopier/issues)



Don't hesitate ;)