Expose merge conflicts in the JavaScript editor. This fixes #23

assets/script.js

@@ -78,15 +78,27 @@ function openEditor() {
             // Update body:
             rendered.innerHTML = result.rendered;
 
+            if (result.conflict) {
+                form.elements.title.value = result.title;
+                form.elements.body.value = result.body;
+            }
+
             // Update form:
             form.elements.base_revision.value = result.revision;
             for (const element of form.elements) {
                 element.defaultValue = element.value;
             }
 
+            if (!result.conflict) {
                 container.classList.remove('edit');
+            }
 
             textarea.disabled = false;
+
+            if (result.conflict) {
+                alert("Your edit came into conflict with another change and has not been saved.\n" +
+                    "Please resolve the merge conflict and save again.");
+            }
         }).catch(err => {
             textarea.disabled = false;
             console.error(err);

src/resources/article_resource.rs

@@ -133,9 +133,11 @@ impl Resource for ArticleResource {
 
         #[derive(Serialize)]
         struct PutResponse<'a> {
+            conflict: bool,
             slug: &'a str,
             revision: i32,
             title: &'a str,
+            body: Option<&'a str>,
             rendered: &'a str,
             last_updated: &'a str,
         }
@@ -150,15 +152,17 @@ impl Resource for ArticleResource {
             .and_then(move |update: UpdateArticle| {
                 self.state.update_article(self.article_id, update.base_revision, update.title, update.body, identity)
             })
-            .and_then(|updated| {
-                let updated = updated.unwrap();
-                futures::finished(Response::new()
+            .and_then(|updated| match updated {
+                UpdateResult::Success(updated) =>
+                    Ok(Response::new()
                         .with_status(hyper::StatusCode::Ok)
                         .with_header(ContentType(APPLICATION_JSON.clone()))
                         .with_body(serde_json::to_string(&PutResponse {
+                            conflict: false,
                             slug: &updated.slug,
                             revision: updated.revision,
                             title: &updated.title,
+                            body: None,
                             rendered: &Template {
                                 title: &updated.title,
                                 rendered: render_markdown(&updated.body),
@@ -169,7 +173,33 @@ impl Resource for ArticleResource {
                                 updated.author.as_ref().map(|x| &**x)
                             ),
                         }).expect("Should never fail"))
+                    ),
+                UpdateResult::RebaseConflict(RebaseConflict {
+                    base_article, title, body
+                }) => {
+                    let title = title.flatten();
+                    let body = body.flatten();
+                    Ok(Response::new()
+                        .with_status(hyper::StatusCode::Ok)
+                        .with_header(ContentType(APPLICATION_JSON.clone()))
+                        .with_body(serde_json::to_string(&PutResponse {
+                            conflict: true,
+                            slug: &base_article.slug,
+                            revision: base_article.revision,
+                            title: &title,
+                            body: Some(&body),
+                            rendered: &Template {
+                                title: &title,
+                                rendered: render_markdown(&body),
+                            }.to_string(),
+                            last_updated: &last_updated(
+                                base_article.article_id,
+                                &Local.from_utc_datetime(&base_article.created),
+                                base_article.author.as_ref().map(|x| &**x)
+                            ),
+                        }).expect("Should never fail"))
                     )
+                }
             })
         )
     }

src/state.rs

@@ -58,16 +58,6 @@ pub enum UpdateResult {
     RebaseConflict(RebaseConflict),
 }
 
-impl UpdateResult {
-    // TODO Move to mod tests below
-    pub fn unwrap(self) -> models::ArticleRevision {
-        match self {
-            UpdateResult::Success(x) => x,
-            _ => panic!("Expected success")
-        }
-    }
-}
-
 fn decide_slug(conn: &SqliteConnection, article_id: i32, prev_title: &str, title: &str, prev_slug: Option<&str>) -> Result<String, Error> {
     let base_slug = ::slug::slugify(title);
 
@@ -485,6 +475,15 @@ mod test {
     use super::*;
     use db;
 
+    impl UpdateResult {
+        pub fn unwrap(self) -> models::ArticleRevision {
+            match self {
+                UpdateResult::Success(x) => x,
+                _ => panic!("Expected success")
+            }
+        }
+    }
+
     macro_rules! init {
         ($state:ident) => {
             let db = db::test_connection();