Deserialize components properly on MessageUpdateEvent (#3316)

Author: jamesbt365

src/model/channel/message.rs

@@ -22,7 +22,7 @@ use crate::gateway::ShardMessenger;
 #[cfg(feature = "model")]
 use crate::http::{CacheHttp, Http};
 use crate::model::prelude::*;
-use crate::model::utils::{deserialize_val, discord_colours, StrOrInt};
+use crate::model::utils::{deserialize_components, discord_colours, StrOrInt};
 #[cfg(all(feature = "model", feature = "cache"))]
 use crate::utils;
 
@@ -151,54 +151,6 @@ pub struct Message {
     pub poll: Option<Box<Poll>>,
 }
 
-// Custom deserialize function to deserialize components safely without knocking the whole message
-// out when new components are found but not supported.
-fn deserialize_components<'de, D>(deserializer: D) -> Result<Vec<ActionRow>, D::Error>
-where
-    D: Deserializer<'de>,
-{
-    struct ComponentsVisitor;
-
-    impl<'de> Visitor<'de> for ComponentsVisitor {
-        type Value = Vec<ActionRow>;
-
-        fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            formatter.write_str("a sequence of ActionRow elements")
-        }
-
-        fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
-        where
-            A: serde::de::SeqAccess<'de>,
-        {
-            let mut components = Vec::with_capacity(seq.size_hint().unwrap_or_default());
-
-            while let Some(map) = seq.next_element::<JsonMap>()? {
-                // We deserialize only the `kind` field to determine the component type.
-                // We later use this to check if its a supported component before deserializing the
-                // entire payload.
-                let raw_kind =
-                    map.get("type").ok_or_else(|| DeError::missing_field("type"))?.clone();
-                let kind: i64 = deserialize_val(raw_kind)?;
-
-                // Action rows are the only top level component supported in serenity at this time.
-                if kind == 1 {
-                    let value = Value::from(map);
-                    components
-                        .push(ActionRow::deserialize(value).map_err(serde::de::Error::custom)?);
-                } else {
-                    // Top level component is not an action row and cannot be supported on
-                    // serenity@current without breaking changes, so we skip them.
-                    tracing::debug!("Skipping component with unsupported kind: {kind}");
-                }
-            }
-
-            Ok(components)
-        }
-    }
-
-    deserializer.deserialize_seq(ComponentsVisitor)
-}
-
 #[cfg(feature = "model")]
 impl Message {
     /// Crossposts this message.

src/model/event.rs

@@ -15,6 +15,7 @@ use crate::model::utils::{
     deserialize_val,
     emojis,
     members,
+    optional_deserialize_components,
     remove_from_map,
     remove_from_map_opt,
     stickers,
@@ -531,6 +532,7 @@ pub struct MessageUpdateEvent {
     pub interaction_metadata: Option<Option<Box<MessageInteractionMetadata>>>,
     #[serde(default, deserialize_with = "deserialize_some")]
     pub thread: Option<Option<GuildChannel>>,
+    #[serde(default, deserialize_with = "optional_deserialize_components")]
     pub components: Option<Vec<ActionRow>>,
     pub sticker_items: Option<Vec<StickerItem>>,
     pub position: Option<Option<u64>>,

src/model/mod.rs

@@ -62,7 +62,7 @@ pub use self::timestamp::Timestamp;
 pub mod prelude {
     pub(crate) use std::collections::HashMap;
 
-    pub(crate) use serde::de::{Error as DeError, Visitor};
+    pub(crate) use serde::de::Visitor;
     pub(crate) use serde::{Deserialize, Deserializer};
 
     pub use super::guild::automod::EventType as AutomodEventType;

src/model/utils.rs

@@ -450,3 +450,62 @@ where
         })
         .collect()
 }
+
+// A function used for deserializing components within a MessageUpdateEvent.
+// Due to discord now sending the whole message payload, we don't need to distinguish between None
+// and empty, as such we always return Some.
+pub fn optional_deserialize_components<'de, D>(
+    deserializer: D,
+) -> Result<Option<Vec<ActionRow>>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    deserialize_components(deserializer).map(Some)
+}
+
+// Custom deserialize function to deserialize components safely without knocking the whole message
+// out when new components are found but not supported.
+pub fn deserialize_components<'de, D>(deserializer: D) -> Result<Vec<ActionRow>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    struct ComponentsVisitor;
+
+    impl<'de> Visitor<'de> for ComponentsVisitor {
+        type Value = Vec<ActionRow>;
+
+        fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            formatter.write_str("a sequence of ActionRow elements")
+        }
+
+        fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+        where
+            A: serde::de::SeqAccess<'de>,
+        {
+            let mut components = Vec::with_capacity(seq.size_hint().unwrap_or_default());
+
+            while let Some(map) = seq.next_element::<JsonMap>()? {
+                // We deserialize only the `kind` field to determine the component type.
+                // We later use this to check if its a supported component before deserializing the
+                // entire payload.
+                let raw_kind =
+                    map.get("type").ok_or_else(|| DeError::missing_field("type"))?.clone();
+                let kind: i64 = deserialize_val(raw_kind)?;
+
+                // Action rows are the only top level component supported in serenity at this time.
+                if kind == 1 {
+                    let value = Value::from(map);
+                    components.push(ActionRow::deserialize(value).map_err(DeError::custom)?);
+                } else {
+                    // Top level component is not an action row and cannot be supported on
+                    // serenity@current without breaking changes, so we skip them.
+                    tracing::debug!("Skipping component with unsupported kind: {kind}");
+                }
+            }
+
+            Ok(components)
+        }
+    }
+
+    deserializer.deserialize_seq(ComponentsVisitor)
+}