FEATURE: cache search results for 5 route transitions

DEV: transientCache that can be used to hold data for N route transitions
FEATURE: remember scroll position when hitting back from full page search

app/assets/javascripts/discourse/controllers/full-page-search.js.es6

@@ -1,4 +1,4 @@
-import { translateResults, searchContextDescription } from "discourse/lib/search";
+import { translateResults, searchContextDescription, getSearchKey } from "discourse/lib/search";
 import showModal from 'discourse/lib/show-modal';
 import { default as computed, observes } from 'ember-addons/ember-computed-decorators';
 import Category from 'discourse/models/category';
@@ -64,6 +64,8 @@ export default Ember.Controller.extend({
   canBulkSelect: Em.computed.alias('currentUser.staff'),
 
   search(){
+    const router = Discourse.__container__.lookup('router:main');
+
     this.set("q", this.get("searchTerm"));
     this.set("model", null);
 
@@ -77,8 +79,12 @@ export default Ember.Controller.extend({
       };
     }
 
+    const searchKey = getSearchKey(args);
+
     Discourse.ajax("/search", { data: args }).then(results => {
-      this.set("model", translateResults(results) || {});
+      const model = translateResults(results) || {};
+      router.transientCache('lastSearch', { searchKey, model }, 5);
+      this.set("model", model);
     });
   },
 

app/assets/javascripts/discourse/initializers/page-tracking.js.es6

@@ -6,6 +6,9 @@ export default {
 
   initialize(container) {
 
+    const cache = {};
+    var transitionCount = 0;
+
     // Tell our AJAX system to track a page transition
     const router = container.lookup('router:main');
     router.on('willTransition', function() {
@@ -14,8 +17,23 @@ export default {
 
     router.on('didTransition', function() {
       Em.run.scheduleOnce('afterRender', Ember.Route, cleanDOM);
+      transitionCount++;
+      _.each(cache, (v,k) => {
+        if (v && v.target && v.target < transitionCount) {
+           delete cache[k];
+        }
+      });
     });
 
+
+    router.transientCache = function(key, data, count) {
+      if (data === undefined) {
+        return cache[key];
+      } else {
+        return cache[key] = {data, target: transitionCount + count};
+      }
+    };
+
     const pageTracker = PageTracker.current();
     pageTracker.start();
 

app/assets/javascripts/discourse/lib/search.js.es6

@@ -101,4 +101,9 @@ const searchContextDescription = function(type, name){
   }
 };
 
-export { searchForTerm, searchContextDescription };
+const getSearchKey = function(args){
+  return args.q + "|" + ((args.searchContext && args.searchContext.type) || "") + "|" +
+                      ((args.searchContext && args.searchContext.id) || "")
+};
+
+export { searchForTerm, searchContextDescription, getSearchKey };

app/assets/javascripts/discourse/routes/full-page-search.js.es6

@@ -1,24 +1,37 @@
-import { translateResults } from "discourse/lib/search";
+import { translateResults, getSearchKey } from "discourse/lib/search";
 
 export default Discourse.Route.extend({
-  queryParams: { q: {}, "context-id": {}, context: {} },
+  queryParams: { q: {}, context_id: {}, context: {} },
 
   model(params) {
+    const router = Discourse.__container__.lookup('router:main');
+    var cached = router.transientCache('lastSearch');
+    var args = { q: params.q };
+    if (params.context_id && !args.skip_context) {
+      args.search_context = {
+        type: params.context,
+        id: params.context_id
+      }
+    }
+
+    const searchKey = getSearchKey(args);
+
+    if (cached && cached.data.searchKey === searchKey) {
+      // extend expiry
+      router.transientCache('lastSearch', { searchKey, model: cached.data.model }, 5);
+      return cached.data.model;
+    }
+
     return PreloadStore.getAndRemove("search", function() {
       if (params.q && params.q.length > 2) {
-        var args = { q: params.q };
-        if (params.context_id && !args.skip_context) {
-          args.search_context = {
-            type: params.context,
-            id: params.context_id
-          }
-        }
         return Discourse.ajax("/search", { data: args });
       } else {
         return null;
       }
     }).then(results => {
-      return (results && translateResults(results)) || {};
+      const model = (results && translateResults(results)) || {};
+      router.transientCache('lastSearch', { searchKey, model }, 5);
+      return model;
     });
   },
 

app/assets/javascripts/discourse/views/full-page-search.js.es6

@@ -1,3 +1 @@
-import ScrollTop from "discourse/mixins/scroll-top";
-
-export default Ember.View.extend(ScrollTop, {});
+export default Ember.View.extend({});