Add a function to walk a config and return the requested value.

config.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
+	"reflect"
 
 	"github.com/hjson/hjson-go/v4"
 )
@@ -13,6 +14,8 @@ import (
 var ErrUndefined = errors.New("value not defined")
 var ErrFileNotFound = errors.New("file not found")
 var ErrParse = errors.New("file could not be parsed")
+var ErrType = errors.New("invalid type")
+var ErrKey = errors.New("key not found")
 
 // File and parsing errors
 type ParseError struct{
@@ -104,3 +107,30 @@ func (s ServiceConfig) GetHostPort() (string, error) {
 
 	return ports[0], nil
 }
+
+// Walk a tree of nested structures or maps until the node is found.
+// Node must be of type string or array.
+func GetValue(i interface{}, path string) (interface{}, error) {
+	for _, p := range strings.Split(path, ".") {
+		switch reflect.ValueOf(i).Kind() {
+		case reflect.Struct:
+			v := reflect.ValueOf(i).FieldByName(p)
+			if v.IsValid() == false { return nil, ErrKey }
+			i = v.Interface()
+		case reflect.Map:
+			v := reflect.ValueOf(i)
+			if v.IsValid() == false { return nil, ErrKey }
+			i = v.MapIndex(reflect.ValueOf(p)).Interface()
+		case reflect.Array:
+			return i, nil
+		case reflect.String:
+			return i, nil
+		default:
+			fmt.Printf("%s is not a valid type\n",
+				reflect.TypeOf(i).Kind())
+			return nil, ErrType
+		}
+	}
+
+	return i, nil
+}