From fb9af8411eaa3e38d2f72e28a305772f50042657 Mon Sep 17 00:00:00 2001 From: Cuong Manh Le Date: Thu, 10 Oct 2019 10:19:12 +0700 Subject: [PATCH] encoding/json: support TextUnmarshaler for map keys with string underlying types MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When unmarshaling to a map, the map's key type must either be a string, an integer, or implement encoding.TextUnmarshaler. But for a user defined type, reflect.Kind will not distinguish between the static type and the underlying type. In: var x MyString = "x" t := reflect.TypeOf(x) println(t.Kind() == reflect.String) the Kind of x is still reflect.String, even though the static type of x is MyString. Moreover, checking for the map's key type is a string occurs first, so even if the map key type MyString implements encoding.TextUnmarshaler, it will be ignored. To fix the bug, check for encoding.TextUnmarshaler first. Fixes #34437 Change-Id: I780e0b084575e1dddfbb433fe03857adf71d05fb Reviewed-on: https://go-review.googlesource.com/c/go/+/200237 Run-TryBot: Cuong Manh Le TryBot-Result: Gobot Gobot Reviewed-by: Daniel Martí --- src/encoding/json/decode.go | 4 ++-- src/encoding/json/decode_test.go | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+), 2 deletions(-) diff --git a/src/encoding/json/decode.go b/src/encoding/json/decode.go index 407fbcedbe..86d8a69db7 100644 --- a/src/encoding/json/decode.go +++ b/src/encoding/json/decode.go @@ -773,14 +773,14 @@ func (d *decodeState) object(v reflect.Value) error { kt := t.Key() var kv reflect.Value switch { - case kt.Kind() == reflect.String: - kv = reflect.ValueOf(key).Convert(kt) case reflect.PtrTo(kt).Implements(textUnmarshalerType): kv = reflect.New(kt) if err := d.literalStore(item, kv, true); err != nil { return err } kv = kv.Elem() + case kt.Kind() == reflect.String: + kv = reflect.ValueOf(key).Convert(kt) default: switch kt.Kind() { case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: diff --git a/src/encoding/json/decode_test.go b/src/encoding/json/decode_test.go index 4cbd2172d0..498bd97b46 100644 --- a/src/encoding/json/decode_test.go +++ b/src/encoding/json/decode_test.go @@ -2411,3 +2411,23 @@ func TestUnmarshalRecursivePointer(t *testing.T) { t.Fatal(err) } } + +type textUnmarshalerString string + +func (m *textUnmarshalerString) UnmarshalText(text []byte) error { + *m = textUnmarshalerString(strings.ToLower(string(text))) + return nil +} + +// Test unmarshal to a map, with map key is a user defined type. +// See golang.org/issues/34437. +func TestUnmarshalMapWithTextUnmarshalerStringKey(t *testing.T) { + var p map[textUnmarshalerString]string + if err := Unmarshal([]byte(`{"FOO": "1"}`), &p); err != nil { + t.Fatalf("Unmarshal unexpected error: %v", err) + } + + if _, ok := p["foo"]; !ok { + t.Errorf(`Key "foo" is not existed in map: %v`, p) + } +} -- 2.50.0