Slug Driver Support (#2456)

- Support slug drivers for core's sluggable models, easily extends to other models
- Add automated testing for affected single-model API routes
- Fix nickname selection UI
- Serialize slugs as `slug` attribute
- Make min search length a constant

js/src/forum/resolvers/DiscussionPageResolver.ts

@@ -1,15 +1,6 @@
 import DefaultResolver from '../../common/resolvers/DefaultResolver';
 import DiscussionPage from '../components/DiscussionPage';
 
-/**
- * This isn't exported as it is a temporary measure.
- * A more robust system will be implemented alongside UTF-8 support in beta 15.
- */
-function getDiscussionIdFromSlug(slug: string | undefined) {
-  if (!slug) return;
-  return slug.split('-')[0];
-}
-
 /**
  * A custom route resolver for DiscussionPage that generates the same key to all posts
  * on the same discussion. It triggers a scroll when going from one post to another
@@ -18,17 +9,32 @@ function getDiscussionIdFromSlug(slug: string | undefined) {
 export default class DiscussionPageResolver extends DefaultResolver {
   static scrollToPostNumber: string | null = null;
 
+  /**
+   * Remove optional parts of a discussion's slug to keep the substring
+   * that bijectively maps to a discussion object. By default this just
+   * extracts the numerical ID from the slug. If a custom discussion
+   * slugging driver is used, this may need to be overriden.
+   * @param slug
+   */
+  canonicalizeDiscussionSlug(slug: string | undefined) {
+    if (!slug) return;
+    return slug.split('-')[0];
+  }
+
+  /**
+   * @inheritdoc
+   */
   makeKey() {
     const params = { ...m.route.param() };
     if ('near' in params) {
       delete params.near;
     }
-    params.id = getDiscussionIdFromSlug(params.id);
+    params.id = this.canonicalizeDiscussionSlug(params.id);
     return this.routeName.replace('.near', '') + JSON.stringify(params);
   }
 
   onmatch(args, requestedPath, route) {
-    if (app.current.matches(DiscussionPage) && getDiscussionIdFromSlug(args.id) === getDiscussionIdFromSlug(m.route.param('id'))) {
+    if (app.current.matches(DiscussionPage) && this.canonicalizeDiscussionSlug(args.id) === this.canonicalizeDiscussionSlug(m.route.param('id'))) {
       // By default, the first post number of any discussion is 1
       DiscussionPageResolver.scrollToPostNumber = args.near || '1';
     }