From 396cd361790c7c885df2c7f0531c3ae6f432aee7 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Fri, 26 Aug 2011 12:27:33 +0400
Subject: [PATCH] json: fix decode bug with struct tag names with ,opts being
 ignored

When the encoder was updated to respect the ",omitempty"
struct tag options, the decoder half was never updated to know
about the new struct tag format. (the format is now an optional
name, followed by zero or more ",option" strings)

This only affected people who used ",omitempty" along with
a field name. In that case, the serialized JSON wouldn't
decode to the original value.

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/4965049
---
 src/pkg/json/decode.go      | 12 +++++++++++-
 src/pkg/json/decode_test.go |  6 +++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/pkg/json/decode.go b/src/pkg/json/decode.go
index 4f6562bd55..6782c76c4e 100644
--- a/src/pkg/json/decode.go
+++ b/src/pkg/json/decode.go
@@ -486,7 +486,7 @@ func (d *decodeState) object(v reflect.Value) {
 			if isValidTag(key) {
 				for i := 0; i < sv.NumField(); i++ {
 					f = st.Field(i)
-					if f.Tag.Get("json") == key {
+					if tagName(f.Tag.Get("json")) == key {
 						ok = true
 						break
 					}
@@ -918,3 +918,13 @@ func unquoteBytes(s []byte) (t []byte, ok bool) {
 	}
 	return b[0:w], true
 }
+
+// tagName extracts the field name part out of the "json" struct tag
+// value. The json struct tag format is an optional name, followed by
+// zero or more ",option" values.
+func tagName(v string) string {
+	if idx := strings.Index(v, ","); idx != -1 {
+		return v[:idx]
+	}
+	return v
+}
diff --git a/src/pkg/json/decode_test.go b/src/pkg/json/decode_test.go
index a855d60486..4c179de5d0 100644
--- a/src/pkg/json/decode_test.go
+++ b/src/pkg/json/decode_test.go
@@ -262,7 +262,8 @@ type All struct {
 	Float32 float32
 	Float64 float64
 
-	Foo string `json:"bar"`
+	Foo  string `json:"bar"`
+	Foo2 string `json:"bar2,dummyopt"`
 
 	PBool    *bool
 	PInt     *int
@@ -331,6 +332,7 @@ var allValue = All{
 	Float32: 14.1,
 	Float64: 15.1,
 	Foo:     "foo",
+	Foo2:    "foo2",
 	String:  "16",
 	Map: map[string]Small{
 		"17": {Tag: "tag17"},
@@ -391,6 +393,7 @@ var allValueIndent = `{
 	"Float32": 14.1,
 	"Float64": 15.1,
 	"bar": "foo",
+	"bar2": "foo2",
 	"PBool": null,
 	"PInt": null,
 	"PInt8": null,
@@ -481,6 +484,7 @@ var pallValueIndent = `{
 	"Float32": 0,
 	"Float64": 0,
 	"bar": "",
+	"bar2": "",
 	"PBool": true,
 	"PInt": 2,
 	"PInt8": 3,
-- 
2.50.0