From 5ab2f993e3842f902c00fd031556732c5c96a86f Mon Sep 17 00:00:00 2001
From: Nikita Prokopov <prokopov@gmail.com>
Date: Mon, 19 Jan 2015 12:57:58 +0600
Subject: [PATCH] Support for nested maps in `transact!` (also fixes #38)

---
 CHANGELOG.md                    |  1 +
 src/datascript/core.cljs        | 29 ++++++++++++-------
 src/datascript/impl/entity.cljs |  4 +--
 test/test/datascript.cljs       | 49 +++++++++++++++++++++++++++++++--
 4 files changed, 69 insertions(+), 14 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6e9b60c6..bec8f359 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 - Find specifications: collection `:find [?e ...]`, tuple `:find [?e ?v]`, and scalar `:find ?e .`
 - Support for `:db/isComponent` (issue #3)
+- Support for nested maps in `transact!` (also fixes #38)
 - [ BREAKING ] Custom aggregate fns must be called via special syntax (`aggregate` keyword): `(q '[:find (aggregate ?myfn ?e) :in $ ?myfn ...])`. Built-in aggregates work as before: `(q '[:find (count ?e) ...]`
 - Return nil from `entity` when passed nil eid (issue #47)
 
diff --git a/src/datascript/core.cljs b/src/datascript/core.cljs
index 1f47ba03..7b7da85a 100644
--- a/src/datascript/core.cljs
+++ b/src/datascript/core.cljs
@@ -290,22 +290,31 @@
       (update-in [:db-after] with-datom datom)
       (update-in [:tx-data] conj datom)))
 
-(defn reverse-ref [attr]
-  (let [name (name attr)]
-    (when (= "_" (nth name 0))
-      (keyword (namespace attr) (subs name 1)))))
+(defn- reverse-ref? [attr]
+  (= "_" (nth (name attr) 0)))
+
+(defn- reverse-ref [attr]
+  (if (reverse-ref? attr)
+    (keyword (namespace attr) (subs (name attr) 1))
+    (keyword (namespace attr) (str "_" (name attr)))))
 
 (defn- explode [db entity]
   (let [eid (:db/id entity)]
-    (for [[a vs] (dissoc entity :db/id)
-          :let   [reverse-a (reverse-ref a)]
+    (for [[a vs] entity
+          :when  (not= a :db/id)
+          :let   [reverse?   (reverse-ref? a)
+                  straight-a (if reverse? (reverse-ref a) a)
+                  _          (when (and reverse? (not (ref? db straight-a)))
+                               (throw (js/Error. (str "Bad attribute " a ": reverse attribute name requires {:db/valueType :db.type/ref} in schema"))))]
           v      (if (and (or (array? vs) (coll? vs))
                           (not (map? vs))
-                          (multival? db a))
+                          (or reverse? (multival? db a)))
                    vs [vs])]
-      (if reverse-a
-        [:db/add v   reverse-a eid]
-        [:db/add eid a         v]))))
+      (if (and (ref? db straight-a) (map? v)) ;; another entity specified as nested map
+        (assoc v (reverse-ref a) eid)
+        (if reverse?
+          [:db/add v   straight-a eid]
+          [:db/add eid straight-a v])))))
 
 (defn- transact-add [report [_ e a v]]
   (let [tx      (current-tx report)
diff --git a/src/datascript/impl/entity.cljs b/src/datascript/impl/entity.cljs
index 4603ce1b..af188536 100644
--- a/src/datascript/impl/entity.cljs
+++ b/src/datascript/impl/entity.cljs
@@ -125,8 +125,8 @@
   (-lookup [_ attr not-found]
     (if (= attr :db/id)
       eid
-      (if-let [attr (dc/reverse-ref attr)]
-        (-lookup-backwards db eid attr not-found)
+      (if (dc/reverse-ref? attr)
+        (-lookup-backwards db eid (dc/reverse-ref attr) not-found)
         (or (cache attr)
             (if touched
               not-found
diff --git a/test/test/datascript.cljs b/test/test/datascript.cljs
index 0afa264a..f3dbdc40 100644
--- a/test/test/datascript.cljs
+++ b/test/test/datascript.cljs
@@ -414,8 +414,53 @@
       (is (= (d/q '[:find ?n
                     :where [_ :children ?e]
                            [?e :name ?n]] db)
-             #{["Petr"] ["Evgeny"]})))))
-
+             #{["Petr"] ["Evgeny"]})))
+    
+    (is (thrown-with-msg? js/Error #"Bad attribute :_parent"
+      (d/db-with db0 [{:name "Sergey" :_parent 1}])))))
+
+(deftest test-explode-nested-maps
+  (let [schema { :profile { :db/valueType :db.type/ref }}
+        db     (d/empty-db schema)]
+    (are [tx res] (= (d/q '[:find ?e ?a ?v
+                            :where [?e ?a ?v]]
+                          (d/db-with db tx)) res)
+      [ {:db/id 5 :name "Ivan" :profile {:db/id 7 :email "@2"}} ]
+      #{ [5 :name "Ivan"] [5 :profile 7] [7 :email "@2"] }
+         
+      [ {:name "Ivan" :profile {:email "@2"}} ]
+      #{ [1 :name "Ivan"] [1 :profile 2] [2 :email "@2"] }
+         
+      [ {:email "@2" :_profile {:name "Ivan"}} ]
+      #{ [1 :email "@2"] [2 :name "Ivan"] [2 :profile 1] }
+    ))
+  
+  (testing "multi-valued"
+    (let [schema { :profile { :db/valueType :db.type/ref
+                              :db/cardinality :db.cardinality/many }}
+          db     (d/empty-db schema)]
+      (are [tx res] (= (d/q '[:find ?e ?a ?v
+                              :where [?e ?a ?v]]
+                            (d/db-with db tx)) res)
+        [ {:db/id 5 :name "Ivan" :profile {:db/id 7 :email "@2"}} ]
+        #{ [5 :name "Ivan"] [5 :profile 7] [7 :email "@2"] }
+           
+        [ {:db/id 5 :name "Ivan" :profile [{:db/id 7 :email "@2"} {:db/id 8 :email "@3"}]} ]
+        #{ [5 :name "Ivan"] [5 :profile 7] [7 :email "@2"] [5 :profile 8] [8 :email "@3"] }
+
+        [ {:name "Ivan" :profile {:email "@2"}} ]
+        #{ [1 :name "Ivan"] [1 :profile 2] [2 :email "@2"] }
+
+        [ {:name "Ivan" :profile [{:email "@2"} {:email "@3"}]} ]
+        #{ [1 :name "Ivan"] [1 :profile 2] [2 :email "@2"] [1 :profile 3] [3 :email "@3"] }
+           
+        [ {:email "@2" :_profile {:name "Ivan"}} ]
+        #{ [1 :email "@2"] [2 :name "Ivan"] [2 :profile 1] }
+
+        [ {:email "@2" :_profile [{:name "Ivan"} {:name "Petr"} ]} ]
+        #{ [1 :email "@2"] [2 :name "Ivan"] [2 :profile 1] [3 :name "Petr"] [3 :profile 1] }
+      ))))
+    
 (deftest test-joins
   (let [db (-> (d/empty-db)
                (d/db-with [ { :db/id 1, :name  "Ivan", :age   15 }