Allows custom values of hooks to be entered into a map

[baagod]

When we want to convert the mapping value to a structure field, we can easily convert it by hook：

type Message struct {
	Content string    `json:"content"`
	Time    time.Time `json:"time"`
}

var result Message

decoder, _ := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
	DecodeHook: func(f reflect.Type, t reflect.Type, data any) (any, error) {
		if t == reflect.TypeOf(time.Time{}) {
			msgTime, _ := time.ParseInLocation(time.DateTime, data.(string), time.Local)
			return msgTime, nil
		}
		return data, nil
	},
	Result:  &result,
	TagName: "json",
})

input := map[string]any{"content": "testMsg", "time": "2024-07-17 11:09:23"}
_ = decoder.Decode(input)
// result => Message[Content="testMsg" Time=2024-07-17 11:09:23 +0800 CST]

However, when you need to convert the structure field values to 'map' in the same way, this doesn't work:

type Message struct {
	Content string    `json:"content"`
	Time    time.Time `json:"time"`
}

result := map[string]any{}
decoder, _ := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
	DecodeHook: func(f reflect.Type, t reflect.Type, data any) (any, error) {
		if f == reflect.TypeOf(&time.Time{}) {
			msgTime, _ := data.(*time.Time)
			return msgTime.Format(time.DateTime), nil
		}
		return data, nil
	},
	Result:  &result,
	TagName: "json",
})

input := Message{"testMsg", time.Now()}
if err := decoder.Decode(input); err != nil {
	fmt.Println("err:", err)
}

fmt.Printf("%+v\n", result)

得到一个错误：err: 'time' expected a map, got 'string'.

该提交正是为了解决这个问题，现在执行上面的代码不会再报错，将输出：map[content:"testMsg" time:"2024-07-17 11:24:27"].