use gob to instead json to store pk & added json type

cache.go

@@ -1,10 +1,11 @@
 package core
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
 	"time"
+	"bytes"
+	"encoding/gob"
 )
 
 const (
@@ -47,16 +48,20 @@ type Cacher interface {
 }
 
 func encodeIds(ids []PK) (string, error) {
-	b, err := json.Marshal(ids)
-	if err != nil {
-		return "", err
-	}
-	return string(b), nil
+	buf := new(bytes.Buffer)
+	enc := gob.NewEncoder(buf)
+	err := enc.Encode(ids)
+
+	return buf.String(), err
 }
 
+
 func decodeIds(s string) ([]PK, error) {
 	pks := make([]PK, 0)
-	err := json.Unmarshal([]byte(s), &pks)
+
+	dec := gob.NewDecoder(bytes.NewBufferString(s))
+	err := dec.Decode(&pks)
+
 	return pks, err
 }
 

type.go

@@ -101,6 +101,8 @@ var (
 	Serial    = "SERIAL"
 	BigSerial = "BIGSERIAL"
 
+	Json = "JSON"
+
 	SqlTypes = map[string]int{
 		Bit:       NUMERIC_TYPE,
 		TinyInt:   NUMERIC_TYPE,
@@ -112,6 +114,7 @@ var (
 
 		Enum: TEXT_TYPE,
 		Set:  TEXT_TYPE,
+		Json: TEXT_TYPE,
 
 		Char:       TEXT_TYPE,
 		Varchar:    TEXT_TYPE,
@@ -229,7 +232,6 @@ var (
 )
 
 func Type2SQLType(t reflect.Type) (st SQLType) {
-
 	switch k := t.Kind(); k {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32:
 		st = SQLType{Int, 0, 0}