Improve pagination

project.clj

@@ -8,7 +8,7 @@
                  [duct/module.logging "0.4.0"]
                  [duct/module.web "0.7.0"]
                  [duct/module.ataraxy "0.3.0"]
-                 [duct/module.cljs "0.4.0" :exclusions [org.clojure/clojurescript]]
+                 [duct/module.cljs "0.4.1" :exclusions [org.clojure/clojurescript]]
                  [duct/module.sql "0.5.0"]
 
                  [duct/middleware.buddy "0.1.0"]
@@ -27,7 +27,7 @@
                  [org.clojure/core.async "0.4.490"]
                  [org.postgresql/postgresql "42.2.5"]]
   :middleware [lein-duct.plugin/middleware]
-  :plugins [[duct/lein-duct "0.11.2"]]
+  :plugins [[duct/lein-duct "0.12.0"]]
   :main ^:skip-aot conduit.main
   :resource-paths ["resources" "target/resources"]
   :prep-tasks     ["javac" "compile" ["run" ":duct/compiler"]]
@@ -43,7 +43,7 @@
                   :resource-paths ["dev/resources"]
                   :dependencies   [ ;; cljs
                                    [cider/piggieback "0.4.0"]
-                                   [walkable/duct.server.figwheel "0.4.0-SNAPSHOT" :exclusions [org.clojure/clojurescript]]
+                                   [duct/server.figwheel "0.3.1" :exclusions [org.clojure/clojurescript]]
                                    [org.clojure/test.check "0.10.0-alpha3"]
                                    [devcards "0.2.6" :exclusions [org.clojure/clojurescript]]
 

resources/conduit/config.edn

@@ -47,8 +47,7 @@
             :user/whoami
             "user"
 
-            [:feed.global/articles :feed.global/next-id
-             :feed.personal/articles :feed.personal/next-id]
+            [:feed.global/articles :feed.personal/articles]
             "article"
 
             :tags/all
@@ -74,14 +73,19 @@
 
            :comment/author [:comment/author-id :user/id]}
 
-   :pseudo-columns {:pagination/total   [:count-*]
-                    :pagination/last-id [:max :article/id]}
+   :pseudo-columns {}
 
    :aggregators {[:article/liked-by-count :user/followed-by-count :tag/count]
                  [:count-*]
 
-                 [:feed.global/next-id :feed.personal/next-id]
-                 :article/id
+                 :app.articles.list/total-items
+                 [:count-*]
+
+                 :app.articles.list/first-item-id
+                 [:min :article/id]
+
+                 :app.articles.list/last-item-id
+                 [:max :article/id]
 
                  [:user/followed-by-me :article/liked-by-me]
                  [:< 0 [:count-*]]}
@@ -91,7 +95,7 @@
                     :user/articles :article/author}
 
    :extra-conditions
-   {[:feed.personal/articles :feed.personal/next-id]
+   {[:feed.personal/articles]
     {:article/author {:user/followed-by [:= app/current-user :user/id]}}
 
     :article/liked-by-me

src/conduit/handler/mutations.clj

@@ -124,3 +124,21 @@
     (if current-user
       (article/remove-tag db current-user article-id tag)
       {})))
+
+(defmutation conduit.ui.pagination/next-page [page-ident]
+  (action [{:keys         [parser] :app/keys [db current-user] :as env
+            list-subquery :query}]
+    (let [next-page-ident-value (assoc page-ident :app.articles.list.page/operation :next)
+          next-page-ident       [:app.articles/list next-page-ident-value]]
+      (-> env
+        (parser [{next-page-ident list-subquery}])
+        (get next-page-ident)))))
+
+(defmutation conduit.ui.pagination/previous-page [page-ident]
+  (action [{:keys [parser] :app/keys [db current-user] :as env
+            list-subquery :query}]
+    (let [next-page-ident-value (assoc page-ident :app.articles.list.page/operation :previous)
+          next-page-ident       [:app.articles/list next-page-ident-value]]
+      (-> env
+        (parser [{next-page-ident list-subquery}])
+        (get next-page-ident)))))

src/conduit/handler/walkable.clj

@@ -11,154 +11,139 @@
             [conduit.handler.mutations :as mutations]
             [fulcro.server :as server :refer [server-mutate]]
             [com.wsscode.pathom.core :as p]
+            [conduit.util :as util :refer [list-ident list-ident-value]]
             [clojure.spec.alpha :as s]))
 
 (defn get-items-subquery [query]
   (->> query
-    (some #(and (map? %) (get % :pagination/items)))))
-
-(defn query-params [env]
-  (let [{:pagination/keys [size start end] :or {size 10}} (env/params env)]
-    {:order-by [:article/id (if-not (number? end) :desc :asc)]
-     :filters  (cond
-                 (number? end)
-                 [:<= :article/id end]
-                 (number? start)
-                 [:<= start :article/id])}))
-
-(defn extra-filter [env]
-  (let [{:pagination/keys [list-type list-id]} (env/params env)]
-    (case list-type
-      :liked-articles/by-user-id
-      {:article/liked-by [:= :user/id list-id]}
-
-      :owned-articles/by-user-id
-      [:= :article/author-id list-id]
-
-      :articles/by-tag
-      {:article/tags [:= :tag/tag list-id]}
-
-      ;; default
+    (some #(and (map? %) (get % :app.articles.list/current-page)))
+    (some #(and (map? %) (get % :app.articles.list.page/items)))))
+
+(defn page-filters [{:app.articles.list/keys [direction]
+                     :app.articles.list.page/keys [operation start end]}]
+  (if (= :forward direction)
+    (case operation
+      :current
+      [:>= start :article/id end]
+
+      :next
+      [:> end :article/id]
+
+      :previous
+      [:> :article/id start]
+
+      ;; else
+      nil)
+    (case operation
+      :current
+      [:<= start :article/id end]
+
+      :next
+      [:< end :article/id]
+
+      :previous
+      [:< :article/id start]
+
+      ;; else
       nil)))
 
+(defn order-by [{:app.articles.list/keys [direction]
+                 :app.articles.list.page/keys [operation]}]
+  [:article/id (if (and (= direction :forward) (not= operation :previous))
+                 :desc
+                 :asc)])
+
+(defn list-filters [{:app.articles.list/keys [list-type list-id]}]
+  (case list-type
+    :app.articles/liked-by-user
+    {:article/liked-by [:= :user/id list-id]}
+
+    :app.articles/owned-by-user
+    [:= :article/author-id list-id]
+
+    :app.articles/with-tag
+    {:article/tags [:= :tag/tag list-id]}
+
+    ;; default
+    nil))
+
 (defn merge-filters [xs]
   (let [xs (remove nil? xs)]
     (when (seq xs)
       (if (= 1 (count xs))
         (first xs)
         (into [:and] xs)))))
 
-(defn next-id [env]
-  (let [{:pagination/keys [list-type list-id size start end] :or {size 10}} (env/params env)
-
-        {:keys [parser query]} env
-
-        query-root
-        (cond
-          (= [list-type list-id] [:articles/by-feed :personal])
-          :feed.personal/next-id
-
-          :default
-          :feed.global/next-id)
-
-        params {:order-by [:article/id :desc]
-                :limit    1
-                :offset   (when-not (number? end) size)
-                :filters  (merge-filters
-                            [(extra-filter env)
-                             (cond
-                               (number? end)
-                               [:< :article/id end]
-                               (number? start)
-                               [:<= :article/id start])])}]
-    (-> (parser env [(list query-root params)])
-      (get query-root))))
-
-(defn previous-id [env]
-  (let [{:pagination/keys [list-type list-id size start end] :or {size 10}} (env/params env)
-
-        {:keys [parser query]} env
-        query-root
-        (cond
-          (= [list-type list-id] [:articles/by-feed :personal])
-          :feed.personal/next-id
-
-          :default
-          :feed.global/next-id)
-
-        params {:order-by [:article/id :asc]
-                :limit    1
-                :offset   (when (number? end) size)
-                :filters  (merge-filters
-                            [(extra-filter env)
-                             (cond
-                               (number? end)
-                               [:<= end :article/id]
-                               (number? start)
-                               [:< start :article/id])])}]
-    (when (or end start)
-      (-> (parser env [(list query-root params)])
-        (get query-root)))))
-
-(defn fetch-items [env]
-  (let [{:pagination/keys [list-type list-id size start end] :or {size 10}} (env/params env)
-
-        {:keys [parser query]} env
-
-        query-root
-        (cond
-          (= [list-type list-id] [:articles/by-feed :personal])
-          :feed.personal/articles
-
-          :default
-          :feed.global/articles)
-
-        params      {:order-by [:article/id (if (number? end) :asc :desc)]
-                     :limit    size
-                     :filters  (merge-filters
-                                 [(extra-filter env)
-                                  (cond
-                                    (number? end)
-                                    [:<= end :article/id]
-                                    (number? start)
-                                    [:<= :article/id start])])}
-        items-query [{(list query-root params) (get-items-subquery query)}]]
+(defn fetch-items
+  [query-root params {:keys [parser query] :as env}]
+  (let [items-query
+        [{(list query-root params) (get-items-subquery query)}]]
     (-> (parser env items-query)
       (get query-root))))
 
-(defn paginated-list-resolver [env]
-  (if (not= :paginated-list/articles (env/dispatch-key env))
+(defn query-root
+  [{:app.articles.list/keys [list-type list-id]}]
+  (cond
+    (= [list-type list-id] [:app.articles/on-feed :personal])
+    :feed.personal/articles
+
+    :default
+    :feed.global/articles))
+
+(defn fetch-list-stats
+  [query-root list-filters {:keys [parser] :as env}]
+  (let [query [{(list query-root {:filters list-filters})
+                [:app.articles.list/first-item-id
+                 :app.articles.list/last-item-id
+                 :app.articles.list/total-items]}]]
+    (-> (parser env query)
+      (get query-root)
+      first)))
+
+(defn article-list-resolver [env]
+  (if (not= :app.articles/list (env/dispatch-key env))
+    ::p/continue
+    (let [page        (env/ident-value env)
+          ident-value (list-ident-value page)
+          direction   (:app.articles.list/direction ident-value)
+          qr          (query-root ident-value)
+          lf          (list-filters ident-value)
+          stats       (fetch-list-stats qr lf env)
+          items       (fetch-items qr
+                        {:order-by (order-by ident-value)
+                         :limit    (:app.articles.list/size ident-value)
+                         :filters  (merge-filters [lf (page-filters page)])}
+                        env)]
+      (merge ident-value
+        (clojure.set/rename-keys stats (when (= :forward direction)
+                                         {:app.articles.list/first-item-id
+                                          :app.articles.list/last-item-id
+                                          :app.articles.list/last-item-id
+                                          :app.articles.list/first-item-id}))
+        {:app.articles.list/current-page
+         (merge ident-value
+           #:app.articles.list.page {:items items
+                                     :start (-> items first :article/id)
+                                     :end   (-> items last :article/id)})}))))
+
+(defn whoami-resolver [env]
+  (if (not= :user/whoami (env/dispatch-key env))
     ::p/continue
-    (let [{:pagination/keys [list-type list-id size start end] :or {size 10}} (env/params env)
-
-          items (fetch-items env)]
-      (merge
-        {(if (number? end) :pagination/end :pagination/start)
-         (or (:article/id (first items)) :no-start)}
-        #:pagination{:size        size
-                     :list-type   list-type
-                     :list-id     list-id
-                     :next-id     (let [n (next-id env)]
-                                    (when (number? n)
-                                      #:pagination{:list-type list-type
-                                                   :list-id   list-id
-                                                   :size      size
-                                                   :start     n}))
-                     :previous-id (let [p (previous-id env)]
-                                    (when (number? p)
-                                      #:pagination{:list-type list-type
-                                                   :list-id   list-id
-                                                   :size      size
-                                                   :end       p}))
-                     :items       items}))))
+    (if-let [user-id (:app/current-user env)]
+      (let [{:keys [parser query]} env
+            ident [:user/by-id user-id]]
+        (-> (parser env [{ident query}])
+          (get ident)))
+      #:user {:id :guest :email "non@exist"})))
 
 (def pathom-parser
   (p/parser
     {:mutate server-mutate
      ::p/plugins
      [(p/env-plugin
         {::p/reader
-         [paginated-list-resolver
+         [article-list-resolver
+          whoami-resolver
           sqb/pull-entities
           p/map-reader
           p/env-placeholder-reader]})]}))