fix bugs with pagination

src/posts.py

@@ -145,14 +145,14 @@ class Posts:
                                      group=True)
                 ])))
 
-    def browse(self, limit, startkey, categories=[], json=True):
+    def browse(self, limit, startkey, categories=[], json=True, backwards=False):
         args = {
                 "num" : limit,
                 "categories" : dumps(categories)
                 }
 
         if startkey:
-            args["startkey"] = startkey
+            args["endkey" if backwards else "startkey"] = startkey
 
         results = self.db.list(
                     "blogPosts/categories",
@@ -163,5 +163,4 @@ class Posts:
         for categories, post in results:
             post["content"] = markdown(post["content"])
             posts.append([categories, post])
-
         return jsonify(posts) if json else posts

src/scripts/browse.tag

@@ -33,14 +33,27 @@
             </a>
           </div>
         </div>
-        <div class="getmore">
-          <button
-            class="btn btn-primary branded"
-            if={opts.state.results.length == pagesize}
-            onclick={getmore}
-          >
-            Next
-          </button>
+        <div class="container">
+          <div class="columns">
+            <div class="col-6 getprev">
+              <button
+                if={pagenum > 0}
+                class="btn btn-primary branded"
+                onclick={getprev}
+              >
+                Previous
+              </button>
+            </div>
+            <div class="col-6 getmore">
+              <button
+                class="btn btn-primary branded"
+                if={opts.state.results.length == pagesize}
+                onclick={getmore}
+              >
+                Next
+              </button>
+            </div>
+          </div>
         </div>
       </div>
     </div>
@@ -62,7 +75,7 @@ self.loading = false;
 self.category = self.opts.state.category_filter;
 self.converter = new showdown.Converter();
 self.lastkey = false;
-self.pagesize = 5;
+self.pagesize = 4;
 
 self.openPost = (id) => {
   return ((ev) => {
@@ -91,7 +104,7 @@ self.filterCategories = (category) => {
     });
     self.opts.state.category_filter = category;
 
-    window.cached(`/blog/getbrowse/${category}/${self.pagesize}/${self.lastkey ? self.lastkey : ""}`)
+    window.cached(`/blog/getbrowse/${category}/${self.pagesize}/${self.startkey ? self.startkey : ""}`)
     .then((resp) => { return resp.json() })
     .then((results) => {
       self.opts.state.results = results;
@@ -102,12 +115,34 @@ self.filterCategories = (category) => {
   })
 }
 
+self.getPrev = (endkey) => {
+    self.update({"loading" : true});
+    var endpoint;
+
+    if (self.category) {
+      endpoint = `/blog/prevbrowse/${self.opts.state.category_filter}/${self.pagesize}/${endkey}`;
+    }
+    else {
+      endpoint = `/blog/prevbrowse/${self.pagesize}/${endkey}`;
+    }
+
+    window.cached(endpoint)
+    .then((resp) => { return resp.json() })
+    .then((results) => {
+      self.opts.state.results = results;
+      self.update({
+        "loading" : false,
+        "pagenum" : self.pagenum-1
+      });
+    });
+}
+
 self.getNext = (startkey) => {
     self.update({"loading" : true});
     var endpoint;
 
     if (self.category) {
-      endpoint = `/blog/getbrowse/${self.category}/${self.pagesize}/${startkey}`;
+      endpoint = `/blog/getbrowse/${self.opts.state.category_filter}/${self.pagesize}/${startkey}`;
     }
     else {
       endpoint = `/blog/getbrowselim/${self.pagesize}/${startkey}`;
@@ -118,7 +153,8 @@ self.getNext = (startkey) => {
     .then((results) => {
       self.opts.state.results = results.slice(1, results.length);
       self.update({
-        "loading" : false
+        "loading" : false,
+        "pagenum" : self.pagenum+1
       });
     });
 }
@@ -140,6 +176,11 @@ self.getmore = (ev) => {
   self.getNext(self.opts.state.results.slice(-1)[0][1].id)
 }
 
+self.getprev = (ev) => {
+  ev.preventDefault();
+  self.getPrev(self.opts.state.results[0][1].id)
+}
+
 self.on("mount", () => {
   if (!self.opts.state.category_filter && !self.opts.state.category_tag) {
     self.getInitial();

src/website.py

@@ -163,7 +163,7 @@ def NeverWhere(configfile=None):
 
     @app.route("/blog/browse/<category>/<start>")
     def browse_categories(category, start):
-        results = posts.browse(5, start*5, categories=[category], json=False)
+        results = posts.browse(4, start*4, categories=[category], json=False)
         return render_template("index.html",
                                 page="browse",
                                 start=start,
@@ -262,6 +262,7 @@ def NeverWhere(configfile=None):
     def getbrowse(limit, startkey):
         return posts.browse(limit, startkey)
 
+    # forwards pagination
     @app.route("/blog/getbrowse/<category>/<limit>/<startkey>")
     def getbycategory(category, limit, startkey):
         return posts.browse(limit, startkey, categories=[category])
@@ -269,6 +270,16 @@ def NeverWhere(configfile=None):
     @app.route("/blog/getbrowse/<category>/<limit>/")
     def getbycategoryinitial(category, limit):
         return posts.browse(limit, False, categories=[category])
+
+    # backwards pagination
+    @app.route("/blog/prevbrowse/<limit>/<endkey>")
+    def prevbrowse(limit, endkey):
+        return posts.browse(limit, endkey, backwards=True)
+
+    @app.route("/blog/prevbrowse/<category>/<limit>/<endkey>")
+    def prevbycategory(category, limit, endkey):
+        return posts.browse(limit, endkey, categories=[category], backwards=True)
+
     return app
 
 app = NeverWhere()