Allow empty messages with attachment.

src/routes/channels/message_send.rs

@@ -12,7 +12,7 @@ use validator::Validate;
 
 #[derive(Validate, Serialize, Deserialize)]
 pub struct Data {
-    #[validate(length(min = 1, max = 2000))]
+    #[validate(length(min = 0, max = 2000))]
     content: String,
     // Maximum length of 36 allows both ULIDs and UUIDs.
     #[validate(length(min = 1, max = 36))]
@@ -27,6 +27,10 @@ pub async fn req(user: User, target: Ref, message: Json<Data>) -> Result<JsonVal
         .validate()
         .map_err(|error| Error::FailedValidation { error })?;
     
+    if message.content.len() == 0 && message.attachment.is_none() {
+        return Err(Error::EmptyMessage);
+    }
+
     let target = target.fetch_channel().await?;
 
     let perm = permissions::PermissionCalculator::new(&user)

src/util/result.rs

@@ -40,6 +40,8 @@ pub enum Error {
     UnknownAttachment,
     #[snafu(display("Cannot edit someone else's message."))]
     CannotEditMessage,
+    #[snafu(display("Cannot send empty message."))]
+    EmptyMessage,
     #[snafu(display("Cannot remove yourself from a group, use delete channel instead."))]
     CannotRemoveYourself,
     #[snafu(display("Group size is too large."))]
@@ -92,6 +94,7 @@ impl<'r> Responder<'r, 'static> for Error {
             Error::UnknownChannel => Status::NotFound,
             Error::UnknownAttachment => Status::BadRequest,
             Error::CannotEditMessage => Status::Forbidden,
+            Error::EmptyMessage => Status::UnprocessableEntity,
             Error::CannotRemoveYourself => Status::BadRequest,
             Error::GroupTooLarge { .. } => Status::Forbidden,
             Error::AlreadyInGroup => Status::Conflict,