Use json.Number when scan to JSONMap (#202)

* Use json.Number when scan to JSONMap

* Add unittest for scanning JSONMap using json.Decoder.UseNumber

json_map.go

@@ -1,6 +1,7 @@
 package datatypes
 
 import (
+ "bytes"
  "context"
  "database/sql/driver"
  "encoding/json"
@@ -42,7 +43,10 @@ func (m *JSONMap) Scan(val interface{}) error {
  return errors.New(fmt.Sprint("Failed to unmarshal JSONB value:", val))
  }
  t := map[string]interface{}{}
- err := json.Unmarshal(ba, &t)
+ rd := bytes.NewReader(ba)
+ decoder := json.NewDecoder(rd)
+ decoder.UseNumber()
+ err := decoder.Decode(&t)
  *m = t
  return err
 }

json_map_test.go

@@ -172,3 +172,13 @@ func TestJSONMap(t *testing.T) {
  }
  }
 }
+
+func TestJSONMap_Scan(t *testing.T) {
+ content := `{"user_id": 1085238870184050699, "name": "Name of user"}`
+ obj := make(datatypes.JSONMap)
+ err := obj.Scan([]byte(content))
+ if err != nil {
+ t.Fatalf("decode error %v", err)
+ }
+ AssertEqual(t, obj["user_id"], 1085238870184050699)
+}