handle map types which implement envconfig.Unmarshaler

envconfig.go

@@ -270,6 +270,12 @@ func isUnmarshaler(t reflect.Type) bool {
 func parseValue(v reflect.Value, str string, ctx *context) (err error) {
  vtype := v.Type()
 
+ // Special case when the type is a map: we need to make the map
+ switch vtype.Kind() {
+ case reflect.Map:
+ v.Set(reflect.MakeMap(vtype))
+ }
+
  // Special case for Unmarshaler
  if isUnmarshaler(vtype) {
  return parseWithUnmarshaler(v, str)

envconfig_test.go

@@ -547,3 +547,22 @@ func TestLeaveNil(t *testing.T) {
  require.Nil(t, err)
  require.Nil(t, conf.MySQL)
 }
+
+type myMapType map[string]int
+
+func (t *myMapType) Unmarshal(s string) error {
+ (*t)[s] = 1
+ return nil
+}
+
+func TestParseMapType(t *testing.T) {
+ var conf struct {
+ Map myMapType
+ }
+
+ os.Setenv("MAP", "a")
+
+ err := envconfig.Init(&conf)
+ require.Nil(t, err)
+ require.Equal(t, 1, conf.Map["a"])
+}