I recently encountered a use case that I need to convert my struct or map value to the type of map[string]interface{}. After surveying and studying for a while, I figure out how to deal with this kind of task and the way to do it.
The following function ConvertStructToMap() is the example of converting Struct or Map data to Map[string]interface{} Type. It receives the argument as interface type and uses reflect function to check the receiver type is correct and what we want. But, it has a constrain, which if you give a map, and Map's key type must be string.
// ConvertStructToMap()
func ConvertStructToMap(message interface{}) (map[string]interface{}, error) {
msg := reflect.ValueOf(message)
msgtype := msg.Type()
// support Struct
if msgtype.Kind() == reflect.Struct {
// message should be tagged by "codec" or "msg"
kv := make(map[string]interface{})
fields := msgtype.NumField()
for i := 0; i < fields; i++ {
field := msgtype.Field(i)
name := field.Name
if n1 := field.Tag.Get("json"); n1 != "" {
name = n1
} else if n2 := field.Tag.Get("msg"); n2 != "" {
name = n2
}
kv[name] = msg.FieldByIndex(field.Index).Interface()
}
return kv, nil
}
// support map[string]interface{} or map[string]string
if msgtype.Kind() != reflect.Map {
return nil, errors.New("message must be a map")
} else if msgtype.Key().Kind() != reflect.String {
return nil, errors.New("map keys must be strings")
}
// Get the interface{}'s current value
kv := make(map[string]interface{})
for _, k := range msg.MapKeys() {
kv[k.String()] = msg.MapIndex(k).Interface()
}
return kv, nil
}
func main() {
fmt.Println("Hello, playground")
structData := struct { Name string `json:"JsonName"`
Score int `msg:"MsgScore"`} {
"john smith", 30, }
kv, err := ConvertStructToMap( structData )
if err != nil {
fmt.Println(err)
}
fmt.Println(kv)
}
How to use it? Here we go! You can try it on the Go Playground:
https://play.golang.org/p/TLKBIbSxIQj
or just take a look at the sample as follows:
// The way to use ConvertStructToMap()
func main() {
structData := struct { Name string `json:"JsonName"`
Score int `msg:"MsgScore"`} {
"john smith", 30, }
kv, err := ConvertStructToMap( structData )
if err != nil {
fmt.Println(err)
}
fmt.Println(kv)
mapData := make(map[string]int)
mapData["Score1"] = 100
mapData["Score2"] = 60
kv, err = ConvertStructToMap( mapData )
if err != nil {
fmt.Println(err)
}
fmt.Println(kv)
}
Run Result==>
map[JsonName:john smith MsgScore:30]
map[Score1:100 Score2:60]
