how to convert map to struct

[Yasutaka Kawamoto]

Please tell me how to covert map to struct.

# I saw the link, but I didn't understand much.

# https://groups.google.com/forum/#!topic/golang-nuts/0ewfMfAGu94

For example,

//define map and initialization

var m url.Vaues (= map[string][]string)  ) 

m["name"] = []string{"go"}

m["address"] = []string{"japan"}

m["hobbies"] = []string{"watching tv", "listen music"}

//define struct

type example struct{

    name string

    address string

    hobbies  []string

}

// convert map to struct

????

// expect like this

example{ "go", "japan",[]string{"watching tv", "listen music"}}

Thank you.

Yasutaka

[Jan Mercl]

On Sat, Oct 12, 2013 at 11:18 AM, Yasutaka Kawamoto <kwm...@gmail.com> wrote:
> Please tell me how to covert map to struct.

// will panic for empty m["name"] or m["address"]
v := example{m["name"][0], m["address"][0], m["hobbies"]}

Also: http://play.golang.org/p/oxnu6K9jgX

-j

[Sebastien Binet]

there is also this nice package:
https://github.com/mitchellh/mapstructure

-s

[Yasutaka Kawamoto]

Thank you Jan.
But I assume the struct has a lot of fields, I think I want to use
reflect package.

Thank you Sebastien.
> https://github.com/mitchellh/mapstructure
This is good package.
But the type like map[string][]string does not seem to support.

In fact, the following message is displayed.
cannot use map[string][]string literal (type map[string][]string) as
type map[string]interface {} in assignment


Yasutaka

[Sebastien Binet]

converting your map[string][]string to something mapstructure can
understand is easy enough:
http://play.golang.org/p/yyDt8gUV-7

-s

[Jan Mercl]

On Sat, Oct 12, 2013 at 11:57 AM, Yasutaka Kawamoto <kwm...@gmail.com> wrote:
> But I assume the struct has a lot of fields, I think I want to use
> reflect package.

It's only _one_ (1!) simple assignment statement. Using reflect for
that is, umm it is, ... err, just forget what I said.

-j

[Yasutaka Kawamoto]

Thanks All,

> http://play.golang.org/p/yyDt8gUV-7
I used this and mapstructure lib, but it is not the result I expect.
http://play.golang.org/p/6L88pgTjQg
// Of course, I know it does't work on playground because use github package.

I don't know what the problem...

yasu

[Dan Kortschak]

You'll need the fields to be exported since the package uses reflect.

[Cao Nguyên]

If performance is not your concern, you can do:

map -> json -> struct (with the encoding/json pkg)

this way you can easyly handle nested map/struct, I mean:

m := make(map[string]interface{})
m["a"] = 1
m["B"] = map[string]int{"C":2, "D":3}

can be convert to Foo

type Foo struct {
  A int `json:"a"`
  B Bar
}
type Bar struct {
  C int
  D int
}

Vào 16:18:32 UTC+7 Thứ bảy, ngày 12 tháng mười năm 2013, Yasutaka Kawamoto đã viết:

[Yasutaka Kawamoto]

To Dan,
Oh... I forgot
Thank you

To Cao,

> map -> json -> struct (with the encoding/json pkg)

That's it!
Although I thought I need to use reflect package, I didn't notice
that I can do with json package.

To All,
I could do.
http://play.golang.org/p/Kd7TRoRG5w

Thank you very much

[Dan Kortschak]

You are using reflect if you are using encoding/json. This is not an
efficient approach.