events: Allow to create custom MessageEventContents

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

@@ -68,6 +68,9 @@ use super::room::message::{
 /// This is the new primary type introduced in [MSC1767] and should not be sent before the end of
 /// the transition period. See the documentation of the [`message`] module for more information.
 ///
+/// To construct a `MessageEventContent` with a custom [`MessageContent`], convert it with
+/// `MessageEventContent::from()` / `.into()`.
+///
 /// `MessageEventContent` can be converted to a [`RoomMessageEventContent`] with a
 /// [`MessageType::Text`]. You can convert it back with
 /// [`MessageEventContent::from_text_room_message()`].
@@ -124,6 +127,12 @@ impl MessageEventContent {
     }
 }
 
+impl From<MessageContent> for MessageEventContent {
+    fn from(message: MessageContent) -> Self {
+        Self { message, relates_to: None }
+    }
+}
+
 impl From<MessageEventContent> for RoomMessageEventContent {
     fn from(content: MessageEventContent) -> Self {
         let MessageEventContent { message, relates_to, .. } = content;
@@ -136,6 +145,9 @@ impl From<MessageEventContent> for RoomMessageEventContent {
 ///
 /// A `MessageContent` must contain at least one message to be used as a fallback text
 /// representation.
+///
+/// To construct a `MessageContent` with custom MIME types, construct a `Vec<Text>` first and use
+/// its `.try_from()` / `.try_into()` implementation that will only fail if the `Vec` is empty.
 #[derive(Clone, Debug, Deserialize)]
 #[serde(try_from = "MessageContentSerDeHelper")]
 pub struct MessageContent(pub(crate) Vec<Text>);
@@ -231,7 +243,11 @@ impl Deref for MessageContent {
 #[derive(Clone, Debug, Serialize, Deserialize)]
 #[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
 pub struct Text {
-    /// The mime type of the `body`.
+    /// The MIME type of the `body`.
+    ///
+    /// This must follow the format defined in [RFC6838].
+    ///
+    /// [RFC6838]: https://datatracker.ietf.org/doc/html/rfc6838
     #[serde(default = "Text::default_mimetype")]
     pub mimetype: String,
 
@@ -249,24 +265,24 @@ pub struct Text {
 }
 
 impl Text {
-    /// Creates a new plain text message body.
-    pub fn plain(body: impl Into<String>) -> Self {
+    /// Creates a new `Text` with the given MIME type and body.
+    pub fn new(mimetype: impl Into<String>, body: impl Into<String>) -> Self {
         Self {
-            mimetype: "text/plain".to_owned(),
+            mimetype: mimetype.into(),
             body: body.into(),
             #[cfg(feature = "unstable-msc3554")]
             lang: None,
         }
     }
 
+    /// Creates a new plain text message body.
+    pub fn plain(body: impl Into<String>) -> Self {
+        Self::new("text/plain", body)
+    }
+
     /// Creates a new HTML-formatted message body.
     pub fn html(body: impl Into<String>) -> Self {
-        Self {
-            mimetype: "text/html".to_owned(),
-            body: body.into(),
-            #[cfg(feature = "unstable-msc3554")]
-            lang: None,
-        }
+        Self::new("text/html", body)
     }
 
     /// Creates a new HTML-formatted message body by parsing the Markdown in `body`.

crates/ruma-common/tests/events/message.rs

@@ -58,6 +58,36 @@ fn plain_text_content_serialization() {
     );
 }
 
+#[test]
+fn unknown_mimetype_content_serialization() {
+    let message_event_content = MessageEventContent::from(
+        MessageContent::try_from(vec![
+            Text::plain("> <@test:example.com> test\n\ntest reply"),
+            Text::new(
+                "application/json",
+                r#"{ "quote": "<@test:example.com> test", "reply": "test reply" }"#,
+            ),
+        ])
+        .unwrap(),
+    );
+
+    assert_eq!(
+        to_json_value(&message_event_content).unwrap(),
+        json!({
+            "org.matrix.msc1767.message": [
+                {
+                    "body": "> <@test:example.com> test\n\ntest reply",
+                    "mimetype": "text/plain",
+                },
+                {
+                    "body": r#"{ "quote": "<@test:example.com> test", "reply": "test reply" }"#,
+                    "mimetype": "application/json",
+                },
+            ]
+        })
+    );
+}
+
 #[test]
 #[cfg(feature = "markdown")]
 fn markdown_content_serialization() {