continuing deferred thought experiment

Signed-off-by: Sean Corfield <sean@corfield.org>

test/next/jdbc/defer_test.clj

@@ -10,23 +10,31 @@
    and next.jdbc.sql API that produces a data structure that
    describes a series of SQL operations to be performed, that
    are held in a dynamic var, and that can be executed at a
-   later time, in a transaction.
-
-   (with-deferred
-     (insert! :foo {:name \"Sean\"})
-     (insert! :bar {:foo_id (deferred-key :foo) :value 42})
-     (insert! :baz {:bar_id (deferred-key :bar) :value 99})
-     (update! :foo {:id (deferred-key :foo)} {:name \"Sean Corfield\"})
-     (delete! :foo {:id (deferred-key :foo)})
-     (delete! :bar {:foo_id (deferred-key :foo)})
-     (delete! :baz {:bar_id (deferred-key :bar)}))
-   "
-  (:require [clojure.test :refer [deftest is testing]]
+   later time, in a transaction."
+  (:require [clojure.test :refer [deftest is testing use-fixtures]]
             [next.jdbc :as jdbc]
-            [next.jdbc.sql.builder :refer [for-insert]]))
+            [next.jdbc.sql.builder :refer [for-delete for-insert for-update]]
+            [next.jdbc.test-fixtures
+             :refer [ds with-test-db]]))
+
+(set! *warn-on-reflection* true)
+
+(use-fixtures :once with-test-db)
 
 (def ^:private ^:dynamic *deferred* nil)
 
+(defn execute-one!
+  "Given a vector containing a SQL statement and parameters, defer
+  execution of that statement."
+  ([sql-p]
+   (execute-one! sql-p {}))
+  ([sql-p opts]
+   (swap! *deferred* conj
+          {:sql-p   sql-p
+           :key-fn  (or (:key-fn opts) (comp first vals))
+           :key     (:key opts)
+           :opts    opts})))
+
 (defn insert!
   "Given a table name, and a data hash map, defer an insertion of the
   data as a single row in the database."
@@ -39,7 +47,29 @@
            :key    (:key opts)
            :opts   opts})))
 
-(defn deferable [transactable stmts]
+(defn update!
+  "Given a table name, a hash map of columns and values to set, and
+  either a hash map of columns and values to search on or a vector
+  of a SQL where clause and parameters, defer an update on the table."
+  ([table key-map where-params]
+   (update! table key-map where-params {}))
+  ([table key-map where-params opts]
+   (swap! *deferred* conj
+          {:sql-p  (for-update table key-map where-params opts)
+           :opts   opts})))
+
+(defn delete!
+  "Given a table name, and either a hash map of columns and values
+  to search on or a vector of a SQL where clause and parameters,
+  defer a delete on the table."
+  ([table where-params]
+   (delete! table where-params {}))
+  ([table where-params opts]
+   (swap! *deferred* conj
+          {:sql-p  (for-delete table where-params opts)
+           :opts   opts})))
+
+(defn deferrable [transactable stmts]
   (reify clojure.lang.IDeref
     (deref [_]
       (let [keys (atom {})]
@@ -54,19 +84,47 @@
                                               {:key v})))
                             v))
                         sql-p)
-                  result (jdbc/execute! conn sql-p opts)]
+                  result (jdbc/execute-one! conn sql-p opts)]
               (when key
-                (swap! keys assoc key (key-fn result))))))))))
+                (swap! keys assoc key (key-fn result))))))
+        @keys))))
 
-(defmacro with-deferred [[conn connectable] & body]
-  `(let [~conn ~connectable]
-     (deferrable ~conn (binding [*deferred* (atom [])] (do ~@body) *deferred*))))
+(defmacro defer-ops [& body]
+  `(binding [*deferred* (atom [])]
+     (do ~@body)
+     *deferred*))
+
+(defmacro with-deferred [connectable & body]
+  `(let [conn# ~connectable]
+     (deferrable conn# (defer-ops ~@body))))
 
 (deftest basic-test
+  (testing "data structures"
     (is (= [{:sql-p ["INSERT INTO foo (name) VALUES (?)" "Sean"]
              :key-fn :GENERATED_KEY
              :key    :id
              :opts   {:key-fn :GENERATED_KEY :key :id}}]
-         (binding [*deferred* (atom [])]
-           (insert! :foo {:name "Sean"} {:key-fn :GENERATED_KEY :key :id})
-           @*deferred*))))
+           @(defer-ops
+             (insert! :foo {:name "Sean"} {:key-fn :GENERATED_KEY :key :id})))))
+  (testing "execution"
+    (let [effects (with-deferred (ds)
+                    (insert! :fruit {:name "Mango"} {:key :test}))]
+      (is (= {:test 1} @effects))
+      (is (= 1 (count (jdbc/execute! (ds)
+                                     ["select * from fruit where name = ?"
+                                      "Mango"])))))
+    (let [effects (with-deferred (ds)
+                    (insert! :fruit {:name "Dragonfruit"} {:key :test})
+                    (update! :fruit {:cost 123} {:name "Dragonfruit"})
+                    (delete! :fruit {:name "Dragonfruit"}))]
+      (is (= {:test 1} @effects))
+      (is (= 0 (count (jdbc/execute! (ds)
+                                     ["select * from fruit where name = ?"
+                                      "Dragonfruit"])))))
+    (let [effects (with-deferred (ds)
+                    (insert! :fruit {:name "Grapefruit" :bad_column 0} {:key :test}))]
+      (is (= :failed (try @effects
+                          (catch Exception _ :failed))))
+      (is (= 0 (count (jdbc/execute! (ds)
+                                     ["select * from fruit where name = ?"
+                                      "Grapefruit"])))))))