bug fixed for PK marshal & unmarshl

pk.go

@@ -1,7 +1,8 @@
 package core
 
 import (
-	"encoding/json"
+	"bytes"
+	"encoding/gob"
 )
 
 type PK []interface{}
@@ -12,14 +13,14 @@ func NewPK(pks ...interface{}) *PK {
 }
 
 func (p *PK) ToString() (string, error) {
-	bs, err := json.Marshal(*p)
-	if err != nil {
-		return "", nil
-	}
-
-	return string(bs), nil
+	buf := new(bytes.Buffer)
+	enc := gob.NewEncoder(buf)
+	err := enc.Encode(*p)
+	return buf.String(), err
 }
 
 func (p *PK) FromString(content string) error {
-	return json.Unmarshal([]byte(content), p)
+	dec := gob.NewDecoder(bytes.NewBufferString(content))
+	err := dec.Decode(p)
+	return err
 }

pk_test.go

@@ -2,6 +2,7 @@ package core
 
 import (
 	"fmt"
+	"reflect"
 	"testing"
 )
 
@@ -19,4 +20,14 @@ func TestPK(t *testing.T) {
 		t.Error(err)
 	}
 	fmt.Println(s)
+
+	if len(*p) != len(*s) {
+		t.Fatal("p", *p, "should be equal", *s)
+	}
+
+	for i, ori := range *p {
+		if ori != (*s)[i] {
+			t.Fatal("ori", ori, reflect.ValueOf(ori), "should be equal", (*s)[i], reflect.ValueOf((*s)[i]))
+		}
+	}
 }