Golang: Converting a struct to a map (to a url.Values string map)

main.go

package main

import (
	"fmt"
	"net/url"
	"reflect"
	"strconv"
)

type Person struct {
	Name string
	Age  uint
}

func main() {
	betty := Person{
		Name: "Betty",
		Age: 82,
	}

	urlValues := structToMap(&betty)
	fmt.Printf("%#v", urlValues)
	// Response...
	// url.Values{"Name":[]string{"Betty"}, "Age":[]string{"82"}}
	// It works! Play with it @ http://play.golang.org/p/R8jhzfI_ac
}

func structToMap(i interface{}) (values url.Values) {
	values = url.Values{}
	iVal := reflect.ValueOf(i).Elem()
	typ := iVal.Type()
	for i := 0; i < iVal.NumField(); i++ {
		f := iVal.Field(i)
		// You ca use tags here...
		// tag := typ.Field(i).Tag.Get("tagname")
		// Convert each type into a string for the url.Values string map
		var v string
		switch f.Interface().(type) {
		case int, int8, int16, int32, int64:
			v = strconv.FormatInt(f.Int(), 10)
		case uint, uint8, uint16, uint32, uint64:
			v = strconv.FormatUint(f.Uint(), 10)
		case float32:
			v = strconv.FormatFloat(f.Float(), 'f', 4, 32)
		case float64:
			v = strconv.FormatFloat(f.Float(), 'f', 4, 64)
		case []byte:
			v = string(f.Bytes())
		case string:
			v = f.String()
		}
		values.Set(typ.Field(i).Name, v)
	}
	return
}

Thanks, I was having a tough time rewriting code to get this working. This code works great.

This func cannot deal with embedded structs.

A shorter version would be

func structToMap(i interface{}) (values url.Values) {
	values = url.Values{}
	iVal := reflect.ValueOf(i).Elem()
	typ := iVal.Type()
	for i := 0; i < iVal.NumField(); i++ {
		values.Set(typ.Field(i).Name, fmt.Sprint(iVal.Field(i)))
	}
	return
}

if the wish only converting interface{} (type of url.Values) to map, then we can do this;
convert url.Values to map string

func someHandler(w http.ResponseWriter, r *http.Request) {
         r.ParseForm()
         mapValOfForm := r.Form.(url.Values)
         fmt.Println(mapValOfForm[formKey])
}

更一步简化完善：

// CMap = url.Values{} = map[string][]string
// struct to CMap, maybe use Encode
func StructToMap(v interface{}) (values CMap) {
	values = NewCMap()
	el := reflect.ValueOf(v)
	if el.Kind() == reflect.Ptr {
		el = el.Elem()
	}
	iVal := el
	typ := iVal.Type()
	for i := 0; i < iVal.NumField(); i++ {
		fi := typ.Field(i)
		name := fi.Tag.Get("json")
		if name == "" {
			name = fi.Name
		}
		values.Set(name, fmt.Sprint(iVal.Field(i)))
	}
	return
}

参考：
https://github.com/dreamlu/gt/blob/2c0230b701fdbec64113111b4c651d0f6e41b040/tool/type/cmap/cmap.go#L107