vendor/github.com/imdario/mergo/README.md

   1 # Mergo
   2
   3 A helper to merge structs and maps in Golang. Useful for configuration default values, avoiding messy if-statements.
   4
   5 Also a lovely [comune](http://en.wikipedia.org/wiki/Mergo) (municipality) in the Province of Ancona in the Italian region Marche.
   6
   7 ![Mergo dall'alto](http://www.comune.mergo.an.it/Siti/Mergo/Immagini/Foto/mergo_dall_alto.jpg)
   8
   9 ## Status
  10
  11 It is ready for production use. It works fine after extensive use in the wild.
  12
  13 [![Build Status][1]][2]
  14 [![GoDoc](https://godoc.org/github.com/imdario/mergo?status.svg)](https://godoc.org/github.com/imdario/mergo)
  15
  16 [1]: https://travis-ci.org/imdario/mergo.png
  17 [2]: https://travis-ci.org/imdario/mergo
  18
  19 ### Important note
  20
  21 Mergo is intended to assign **only** zero value fields on destination with source value. Since April 6th it works like this. Before it didn't work properly, causing some random overwrites. After some issues and PRs I found it didn't merge as I designed it. Thanks to [imdario/mergo#8](https://github.com/imdario/mergo/pull/8) overwriting functions were added and the wrong behavior was clearly detected.
  22
  23 If you were using Mergo **before** April 6th 2015, please check your project works as intended after updating your local copy with ```go get -u github.com/imdario/mergo```. I apologize for any issue caused by its previous behavior and any future bug that Mergo could cause (I hope it won't!) in existing projects after the change (release 0.2.0).
  24
  25 ### Mergo in the wild
  26
  27 - [imdario/zas](https://github.com/imdario/zas)
  28 - [GoogleCloudPlatform/kubernetes](https://github.com/GoogleCloudPlatform/kubernetes)
  29 - [soniah/dnsmadeeasy](https://github.com/soniah/dnsmadeeasy)
  30 - [EagerIO/Stout](https://github.com/EagerIO/Stout)
  31 - [lynndylanhurley/defsynth-api](https://github.com/lynndylanhurley/defsynth-api)
  32 - [russross/canvasassignments](https://github.com/russross/canvasassignments)
  33 - [rdegges/cryptly-api](https://github.com/rdegges/cryptly-api)
  34 - [casualjim/exeggutor](https://github.com/casualjim/exeggutor)
  35 - [divshot/gitling](https://github.com/divshot/gitling)
  36 - [RWJMurphy/gorl](https://github.com/RWJMurphy/gorl)
  37 - [andrerocker/deploy42](https://github.com/andrerocker/deploy42)
  38 - [elwinar/rambler](https://github.com/elwinar/rambler)
  39 - [tmaiaroto/gopartman](https://github.com/tmaiaroto/gopartman)
  40 - [jfbus/impressionist](https://github.com/jfbus/impressionist)
  41 - [Jmeyering/zealot](https://github.com/Jmeyering/zealot)
  42 - [godep-migrator/rigger-host](https://github.com/godep-migrator/rigger-host)
  43 - [Dronevery/MultiwaySwitch-Go](https://github.com/Dronevery/MultiwaySwitch-Go)
  44 - [thoas/picfit](https://github.com/thoas/picfit)
  45 - [mantasmatelis/whooplist-server](https://github.com/mantasmatelis/whooplist-server)
  46 - [jnuthong/item_search](https://github.com/jnuthong/item_search)
  47
  48 ## Installation
  49
  50     go get github.com/imdario/mergo
  51
  52     // use in your .go code
  53     import (
  54         "github.com/imdario/mergo"
  55     )
  56
  57 ## Usage
  58
  59 You can only merge same-type structs with exported fields initialized as zero value of their type and same-types maps. Mergo won't merge unexported (private) fields but will do recursively any exported one. Also maps will be merged recursively except for structs inside maps (because they are not addressable using Go reflection).
  60
  61     if err := mergo.Merge(&dst, src); err != nil {
  62         // ...
  63     }
  64
  65 Additionally, you can map a map[string]interface{} to a struct (and otherwise, from struct to map), following the same restrictions as in Merge(). Keys are capitalized to find each corresponding exported field.
  66
  67     if err := mergo.Map(&dst, srcMap); err != nil {
  68         // ...
  69     }
  70
  71 Warning: if you map a struct to map, it won't do it recursively. Don't expect Mergo to map struct members of your struct as map[string]interface{}. They will be just assigned as values.
  72
  73 More information and examples in [godoc documentation](http://godoc.org/github.com/imdario/mergo).
  74
  75 ### Nice example
  76
  77 ```go
  78 package main
  79
  80 import (
  81         "fmt"
  82         "github.com/imdario/mergo"
  83 )
  84
  85 type Foo struct {
  86         A string
  87         B int64
  88 }
  89
  90 func main() {
  91         src := Foo{
  92                 A: "one",
  93         }
  94
  95         dest := Foo{
  96                 A: "two",
  97                 B: 2,
  98         }
  99
 100         mergo.Merge(&dest, src)
 101
 102         fmt.Println(dest)
 103         // Will print
 104         // {two 2}
 105 }
 106 ```
 107
 108 Note: if test are failing due missing package, please execute:
 109
 110     go get gopkg.in/yaml.v1
 111
 112 ## Contact me
 113
 114 If I can help you, you have an idea or you are using Mergo in your projects, don't hesitate to drop me a line (or a pull request): [@im_dario](https://twitter.com/im_dario)
 115
 116 ## About
 117
 118 Written by [Dario Castañé](http://dario.im).
 119
 120 ## License
 121
 122 [BSD 3-Clause](http://opensource.org/licenses/BSD-3-Clause) license, as [Go language](http://golang.org/LICENSE).