From 851722e46cbb02c31640a0c8a1e0433de195f38a Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Thu, 2 Jun 2022 20:46:41 +0400
Subject: [PATCH] Fix deserialization of `File` when `file_path` or `file_size`
 are missing

---
 CHANGELOG.md      |  2 ++
 src/types/file.rs | 55 +++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fe2e1c0a..692d9e1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,9 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## unreleased
 
+- Fix deserialization of `File` when `file_path` or `file_size` are missing ([#220][pr220])
 - Add `ChatId` and `UserId` to the prelude ([#212][pr212])
 - Add `is_*` methods to `ChatMemberStatus` analogous to the `ChatMember{,Kind}` methods ([#216][pr216])
 
+[pr220]: https://github.com/teloxide/teloxide-core/pull/220
 [pr212]: https://github.com/teloxide/teloxide-core/pull/212
 [pr216]: https://github.com/teloxide/teloxide-core/pull/216
 
diff --git a/src/types/file.rs b/src/types/file.rs
index 82aa237e..05402ffa 100644
--- a/src/types/file.rs
+++ b/src/types/file.rs
@@ -22,11 +22,62 @@ pub struct File {
     pub file_unique_id: String,
 
     /// File size, if known.
+    ///
+    /// **Note:** in the Telegram Bot API this field is optional, however it was
+    /// errourneusly marked as required in Teloxide. To workaround this issue,
+    /// when `file_size` is not present, it is deserialized as [`u32::MAX`].
+    #[serde(default = "default_file_size")]
     pub file_size: u32,
 
     /// File path. Use [`Bot::download_file(file_path, dst)`] to get the file.
     ///
-    /// [`Bot::download_file(file_path, dst)`]:
-    /// crate::net::Download::download_file
+    /// **Note:** in the Telegram Bot API this field is optional, however it was
+    /// errourneusly marked as required in Teloxide. To workaround this issue,
+    /// when `file_path` is not present, it is deserialized as an empty string.
+    ///
+    /// [`Bot::download_file(file_path, dst)`]: crate::net::Download::download_file
+    #[serde(default)]
     pub file_path: String,
 }
+
+const fn default_file_size() -> u32 {
+    u32::MAX
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::types::File;
+
+    #[test]
+    fn no_file_size() {
+        let json =
+            r#"{"file_id":"FILE_ID","file_unique_id":"FILE_UNIQUE_ID","file_path":"FILE_PATH"}"#;
+        let file: File = serde_json::from_str(json).unwrap();
+
+        assert_eq!(
+            file,
+            File {
+                file_id: "FILE_ID".to_owned(),
+                file_unique_id: "FILE_UNIQUE_ID".to_owned(),
+                file_size: u32::MAX,
+                file_path: "FILE_PATH".to_owned(),
+            }
+        );
+    }
+
+    #[test]
+    fn no_file_path() {
+        let json = r#"{"file_id":"FILE_ID","file_unique_id":"FILE_UNIQUE_ID","file_size":42}"#;
+        let file: File = serde_json::from_str(json).unwrap();
+
+        assert_eq!(
+            file,
+            File {
+                file_id: "FILE_ID".to_owned(),
+                file_unique_id: "FILE_UNIQUE_ID".to_owned(),
+                file_size: 42,
+                file_path: "".to_owned(),
+            }
+        );
+    }
+}