Map to struct and vice versa

[Nick Keets]

Is there an easy way to go from a map to a struct and vice versa? e.g. going from:
    m := map[string]interface{}{"a": "x", "b": 5}

to an instance of:
  type T struct {
    A string
    B int
  }

I can do this going through JSON (marshal the map, unmarshal into struct),
but is there a more direct way?

[Amnon]

https://programmersought.com/article/93641771999/

[Mock ***]

Hi Nick,

I understand , please check if this pkg may help you https://github.com/fatih/structs,

Thanks

[Howard C. Shaw III]

The examples given in other responses are great if you need to handle arbitrary or unknown maps and very much fit the 'easy way' part of your initial question. But you also asked at the end 'is there a more direct way?'.

If you actually know what you are getting, you can code it entirely directly:

t := T{

A: m["a"].(string),

B: m["b"].(int),

}

and back again

m2 := map[string]interface{}{}

m2["a"] = t.A

m2["b"] = t.B

https://play.golang.org/p/4OY3QoA5Mr3

Why would you not do this? Because your assignment will panic if you pass an m that is missing "a" or "b". Not fun. (Something like "panic: interface conversion: interface {} is nil, not int") Of course, you can always collect the values from the map into temporaries before creating the type and handle any nils in that process. Or pass your map through a validation step that ensures it is safe to convert before passing it to the conversion.

[Nick Keets]

Thanks everyone for your responses. structs is interesting, but archived, pre modules even. Using reflect directly also doesn't seem that bad and I do want error handling, so it looks like nothing beats JSON in terms of UI.

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