我应该如何在golang中传递param？

Question

I have the follow whole codes:

I hope that string convert map in golang, and use golang reflect.

The following code have simpled from my project.

package main

import (
    "encoding/json"
    "fmt"
    "reflect"
)

func main() {
    jsonStr := `{"name": "thinkerou", "age": 31, "balance": 3.14}`

    var a map[string]interface{}
    var value reflect.Value = reflect.ValueOf(&a)

    // call function and pass param
    f(jsonStr, value)

    // print result
    fmt.Println(value.Kind(), value.Interface())
}

func f(v string, value reflect.Value) {
    personMap := make(map[string]interface{})

    err := json.Unmarshal([]byte(v), &personMap)

    if err != nil {
        panic(err)
    }

    value = reflect.Indirect(value)
    value = reflect.MakeMap(value.Type())
    for k, v := range personMap {
        // set key/value
        value.SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(v))
    }

    // print result
    fmt.Println(value.Kind(), value.Interface())
}

and run it and will get the result:

map map[age:31 balance:3.14 name:thinkerou]
ptr &map[]

I hope the follow result:

map map[age:31 balance:3.14 name:thinkerou]
map map[age:31 balance:3.14 name:thinkerou]

How should I pass reflect.Value param? thanks!

Answer 1

You should be able to get your map from the interface, using type assertion:

a := i.(map[string]interface{})

See "Convert Value type to Map in Golang?"

I have modified your code here.
Note that I don't try to mutate the f(value) argument, but I return it instead.

func f(v string, value reflect.Value) reflect.Value {
  ...
  return value 
}

So the code becomes:

value = f(jsonStr, value)
fmt.Println(value.Kind(), value.Interface().(map[string]interface{}))