encoding/json: skip unexpected null values

As discussed in issue 2540, nulls are allowed for any type in JSON so they should not result in an error during Unmarshal.
Fixes #2540.

R=rsc
CC=golang-dev
https://golang.org/cl/6759043

diff --git a/src/pkg/encoding/json/decode.go b/src/pkg/encoding/json/decode.go
index b06b87af400bf5134e62b2e6285d39e43533af00..1e0c8d4b6e62f55274b7e59cfef5a097c873bc2a 100644 (file)
--- a/src/pkg/encoding/json/decode.go
+++ b/src/pkg/encoding/json/decode.go
@@ -617,12 +617,10 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
        switch c := item[0]; c {
        case 'n': // null
                switch v.Kind() {
-               default:
-                       d.saveError(&UnmarshalTypeError{"null", v.Type()})
                case reflect.Interface, reflect.Ptr, reflect.Map, reflect.Slice:
                        v.Set(reflect.Zero(v.Type()))
+                       // otherwise, ignore null for primitives/string
                }
-
        case 't', 'f': // true, false
                value := c == 't'
                switch v.Kind() {

diff --git a/src/pkg/encoding/json/decode_test.go b/src/pkg/encoding/json/decode_test.go
index f2da141b8f999aa7ba05c2e920415f377b9fd3b2..b9fad0597a6d0d17727f240826d57d005b186951 100644 (file)
--- a/src/pkg/encoding/json/decode_test.go
+++ b/src/pkg/encoding/json/decode_test.go
@@ -953,3 +953,50 @@ func TestInterfaceSet(t *testing.T) {
                }
        }
 }
+
+// JSON null values should be ignored for primitives and string values instead of resulting in an error.
+// Issue 2540
+func TestUnmarshalNulls(t *testing.T) {
+       jsonData := []byte(`{
+               "Bool"    : null, 
+               "Int"     : null, 
+               "Int8"    : null,
+               "Int16"   : null,
+               "Int32"   : null,
+               "Int64"   : null,
+               "Uint"    : null,
+               "Uint8"   : null,
+               "Uint16"  : null,
+               "Uint32"  : null,
+               "Uint64"  : null,
+               "Float32" : null,
+               "Float64" : null,
+               "String"  : null}`)
+
+       nulls := All{
+               Bool:    true,
+               Int:     2,
+               Int8:    3,
+               Int16:   4,
+               Int32:   5,
+               Int64:   6,
+               Uint:    7,
+               Uint8:   8,
+               Uint16:  9,
+               Uint32:  10,
+               Uint64:  11,
+               Float32: 12.1,
+               Float64: 13.1,
+               String:  "14"}
+
+       err := Unmarshal(jsonData, &nulls)
+       if err != nil {
+               t.Errorf("Unmarshal of null values failed: %v", err)
+       }
+       if !nulls.Bool || nulls.Int != 2 || nulls.Int8 != 3 || nulls.Int16 != 4 || nulls.Int32 != 5 || nulls.Int64 != 6 ||
+               nulls.Uint != 7 || nulls.Uint8 != 8 || nulls.Uint16 != 9 || nulls.Uint32 != 10 || nulls.Uint64 != 11 ||
+               nulls.Float32 != 12.1 || nulls.Float64 != 13.1 || nulls.String != "14" {
+
+               t.Errorf("Unmarshal of null values affected primitives")
+       }
+}