types: add StrInt64 type for unmarshalling integer in string

pkg/types/strint.go

@@ -0,0 +1,38 @@
+package types
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+)
+
+type StrInt64 int64
+
+func (s *StrInt64) UnmarshalJSON(body []byte) error {
+	var arg interface{}
+	if err := json.Unmarshal(body, &arg); err != nil {
+		return err
+	}
+
+	switch ta := arg.(type) {
+	case string:
+		// parse string
+		i, err := strconv.ParseInt(ta, 10, 64)
+		if err != nil {
+			return err
+		}
+		*s = StrInt64(i)
+
+	case int64:
+		*s = StrInt64(ta)
+	case int32:
+		*s = StrInt64(ta)
+	case int:
+		*s = StrInt64(ta)
+
+	default:
+		return fmt.Errorf("StrInt64 error: unsupported value type %T", ta)
+	}
+
+	return nil
+}