feat: book id use optional i64

src/model/http_body/book.rs

@@ -1,8 +1,10 @@
 use serde::{Serialize, Deserialize};
+use super::common::{number_stringify, OptionalI64};
 
 #[derive(Serialize)]
 pub struct BookItem {
-    pub id: i64,
+    #[serde(with="number_stringify")]
+    pub id: OptionalI64,
     pub name: String,
 }