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crates/ruma-common/src/events/receipt.rs

@@ -12,7 +12,10 @@ use std::{
 use ruma_macros::{EventContent, OrdAsRefStr, PartialEqAsRefStr, PartialOrdAsRefStr, StringEnum};
 use serde::{Deserialize, Serialize};
 
-use crate::{EventId, MilliSecondsSinceUnixEpoch, OwnedEventId, OwnedUserId, PrivOwnedStr, UserId};
+use crate::{
+    EventId, IdParseError, MilliSecondsSinceUnixEpoch, OwnedEventId, OwnedUserId, PrivOwnedStr,
+    UserId,
+};
 
 /// The content of an `m.receipt` event.
 ///
@@ -106,7 +109,7 @@ pub struct Receipt {
     pub ts: Option<MilliSecondsSinceUnixEpoch>,
 
     /// The thread this receipt applies to.
-    #[serde(rename = "thread_id", skip_serializing_if = "crate::serde::is_default")]
+    #[serde(rename = "thread_id", default, skip_serializing_if = "crate::serde::is_default")]
     pub thread: ReceiptThread,
 }
 
@@ -122,7 +125,7 @@ impl Receipt {
 /// The [thread a receipt applies to].
 ///
 /// This type can hold an arbitrary string. To build this with a custom value, convert it from an
-/// `Option<string>` with `::from()` / `.into()`. [`ReceiptThread::Unthreaded`] can be constructed
+/// `Option<String>` with `::from()` / `.into()`. [`ReceiptThread::Unthreaded`] can be constructed
 /// from `None`.
 ///
 /// To check for values that are not available as a documented variant here, use its string
@@ -168,21 +171,23 @@ impl ReceiptThread {
     }
 }
 
-impl<T> From<Option<T>> for ReceiptThread
+impl<T> TryFrom<Option<T>> for ReceiptThread
 where
     T: AsRef<str> + Into<Box<str>>,
 {
-    fn from(s: Option<T>) -> Self {
-        match s {
+    type Error = IdParseError;
+
+    fn try_from(s: Option<T>) -> Result<Self, Self::Error> {
+        let res = match s {
             None => Self::Unthreaded,
             Some(s) => match s.as_ref() {
                 "main" => Self::Main,
-                s_ref => match EventId::parse(s_ref) {
-                    Ok(event_id) => Self::Thread(event_id),
-                    Err(_) => Self::_Custom(PrivOwnedStr(s.into())),
-                },
+                s_ref if s_ref.starts_with('s') => Self::Thread(EventId::parse(s_ref)?),
+                _ => Self::_Custom(PrivOwnedStr(s.into())),
             },
-        }
+        };
+
+        Ok(res)
     }
 }
 
@@ -209,7 +214,7 @@ mod tests {
             Receipt::new(MilliSecondsSinceUnixEpoch(1_664_702_144_365_u64.try_into().unwrap()));
         assert_eq!(to_json_value(receipt.clone()).unwrap(), json!({ "ts": 1_664_702_144_365_u64 }));
 
-        receipt.thread = ReceiptThread::from(Some("io.ruma.unknown"));
+        receipt.thread = ReceiptThread::try_from(Some("io.ruma.unknown")).unwrap();
         assert_eq!(
             to_json_value(receipt).unwrap(),
             json!({ "ts": 1_664_702_144_365_u64, "thread_id": "io.ruma.unknown" })

crates/ruma-common/src/events/receipt/receipt_thread_serde.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 use super::ReceiptThread;
@@ -18,7 +16,7 @@ impl<'de> Deserialize<'de> for ReceiptThread {
     where
         D: Deserializer<'de>,
     {
-        let s = Option::<Cow<'_, str>>::deserialize(deserializer)?;
-        Ok(s.into())
+        let s = crate::serde::deserialize_cow_str(deserializer)?;
+        Self::try_from(Some(s)).map_err(serde::de::Error::custom)
     }
 }