feat: get amount

src/model/req.rs

@@ -1,7 +1,23 @@
+use std::fmt;
+use std::str::FromStr;
 use serde::{de, Deserialize, Deserializer};
 
 #[derive(Debug, Deserialize)]
 pub struct Params {
     #[serde(default, deserialize_with="empty_string_as_none")]
-    transaction_id: Option<i64>,
-}
+    pub transaction_id: Option<i64>,
+}
+
+// Serde deserialization decorator to map empty Strings to None,
+fn empty_string_as_none<'de, D, T>(de: D) -> Result<Option<T>, D::Error>
+where
+    D: Deserializer<'de>,
+    T: FromStr,
+    T::Err: fmt::Display,
+{
+    let opt = Option::<String>::deserialize(de)?;
+    match opt.as_deref() {
+        None | Some("") => Ok(None),
+        Some(s) => FromStr::from_str(s).map_err(de::Error::custom).map(Some),
+    }
+}