Preconditions to validate db/conn arguments (closes #101)

CHANGELOG.md

@@ -4,6 +4,7 @@
 - lookup refs in JS API `pull`, `pull_many`, `entity` (#94, thx [Matt Senior](https://github.com/mattsenior))
 - fix in Pull API for reverse non-component attributes (#91, thx [Matt Senior](https://github.com/mattsenior))
 - Node.js and Browser repls for dev profile (#93)
+- Preconditions to validate db/conn arguments (#101)
 
 # 0.11.5
 

src/datascript.cljc

@@ -16,7 +16,9 @@
 
 (def  q dq/q)
 (def  entity de/entity)
-(defn entity-db [^Entity entity] (.-db entity))
+(defn entity-db [^Entity entity]
+  {:pre [(de/entity? entity)]}
+  (.-db entity))
 
 (def  datom dc/datom)
 
@@ -36,6 +38,7 @@
   (instance? FilteredDB x))
 
 (defn filter [db pred]
+  {:pre [(dc/db? db)]}
   (if (is-filtered db)
     (let [^FilteredDB fdb db
           u (.-unfiltered-db fdb)]
@@ -45,6 +48,7 @@
 (defn with
   ([db tx-data] (with db tx-data nil))
   ([db tx-data tx-meta]
+    {:pre [(dc/db? db)]}
     (if (is-filtered db)
       (throw (ex-info "Filtered DB cannot be modified" {:error :transaction/filtered}))
       (dc/transact-tx-data (dc/map->TxReport
@@ -55,35 +59,44 @@
                                :tx-meta   tx-meta}) tx-data))))
 
 (defn db-with [db tx-data]
+  {:pre [(dc/db? db)]}
   (:db-after (with db tx-data)))
 
 (defn datoms
-  ([db index] (dc/-datoms db index []))
-  ([db index c1] (dc/-datoms db index [c1]))
-  ([db index c1 c2] (dc/-datoms db index [c1 c2]))
-  ([db index c1 c2 c3] (dc/-datoms db index [c1 c2 c3]))
-  ([db index c1 c2 c3 c4] (dc/-datoms db index [c1 c2 c3 c4])))
+  ([db index]             {:pre [(dc/db? db)]} (dc/-datoms db index []))
+  ([db index c1]          {:pre [(dc/db? db)]} (dc/-datoms db index [c1]))
+  ([db index c1 c2]       {:pre [(dc/db? db)]} (dc/-datoms db index [c1 c2]))
+  ([db index c1 c2 c3]    {:pre [(dc/db? db)]} (dc/-datoms db index [c1 c2 c3]))
+  ([db index c1 c2 c3 c4] {:pre [(dc/db? db)]} (dc/-datoms db index [c1 c2 c3 c4])))
 
 (defn seek-datoms
-  ([db index] (dc/-seek-datoms db index []))
-  ([db index c1] (dc/-seek-datoms db index [c1]))
-  ([db index c1 c2] (dc/-seek-datoms db index [c1 c2]))
-  ([db index c1 c2 c3] (dc/-seek-datoms db index [c1 c2 c3]))
-  ([db index c1 c2 c3 c4] (dc/-seek-datoms db index [c1 c2 c3 c4])))
+  ([db index]             {:pre [(dc/db? db)]} (dc/-seek-datoms db index []))
+  ([db index c1]          {:pre [(dc/db? db)]} (dc/-seek-datoms db index [c1]))
+  ([db index c1 c2]       {:pre [(dc/db? db)]} (dc/-seek-datoms db index [c1 c2]))
+  ([db index c1 c2 c3]    {:pre [(dc/db? db)]} (dc/-seek-datoms db index [c1 c2 c3]))
+  ([db index c1 c2 c3 c4] {:pre [(dc/db? db)]} (dc/-seek-datoms db index [c1 c2 c3 c4])))
 
-(def index-range dc/-index-range)
+(defn index-range [db attr start end]
+  {:pre [(dc/db? db)]}
+  (dc/-index-range db attr start end))
 
 (def entid dc/entid)
 
 ;; Conn
 
+(defn conn? [conn]
+  (and (instance? #?(:clj  clojure.lang.Atom
+                     :cljs cljs.core/Atom) conn)
+       (dc/db? @conn)))
+
 (defn create-conn
   ([] (create-conn dc/default-schema))
   ([schema]
     (atom (empty-db schema)
           :meta { :listeners  (atom {}) })))
 
 (defn -transact! [conn tx-data tx-meta]
+  {:pre [(conn? conn)]}
   (let [report (atom nil)]
     (swap! conn (fn [db]
                   (let [r (with db tx-data tx-meta)]
@@ -94,6 +107,7 @@
 (defn transact!
   ([conn tx-data] (transact! conn tx-data nil))
   ([conn tx-data tx-meta]
+    {:pre [(conn? conn)]}
     (let [report (-transact! conn tx-data tx-meta)]
       (doseq [[_ callback] @(:listeners (meta conn))]
         (callback report))
@@ -102,10 +116,12 @@
 (defn listen!
   ([conn callback] (listen! conn (rand) callback))
   ([conn key callback]
+     {:pre [(conn? conn)]}
      (swap! (:listeners (meta conn)) assoc key callback)
      key))
 
 (defn unlisten! [conn key]
+  {:pre [(conn? conn)]}
   (swap! (:listeners (meta conn)) dissoc key))
 
 
@@ -141,11 +157,14 @@
 (defn resolve-tempid [_db tempids tempid]
   (get tempids tempid))
 
-(def db deref)
+(defn db [conn]
+  {:pre [(conn? conn)]}
+  @conn)
 
 (defn transact
   ([conn tx-data] (transact conn tx-data nil))
   ([conn tx-data tx-meta]
+    {:pre [(conn? conn)]}
     (let [res (transact! conn tx-data tx-meta)]
       #?(:cljs
          (reify
@@ -181,6 +200,7 @@
 (defn transact-async
   ([conn tx-data] (transact-async conn tx-data nil))
   ([conn tx-data tx-meta]
+    {:pre [(conn? conn)]}
     (future-call #(transact! conn tx-data tx-meta))))
 
 (defn- rand-bits [pow]

src/datascript/core.cljc

@@ -405,7 +405,10 @@
                 (btset/slice (.-avet db) (resolve-datom db nil attr start nil)
                              (resolve-datom db nil attr end nil))))
 
-(defn db? [x] (and (instance? ISearch x) (instance? IIndexAccess x) (instance? IDB x)))
+(defn db? [x]
+  (and (satisfies? ISearch x)
+       (satisfies? IIndexAccess x)
+       (satisfies? IDB x)))
 
 ;; ----------------------------------------------------------------------------
 (defrecord-updatable FilteredDB [unfiltered-db pred #?(:clj __hash)]
@@ -516,6 +519,7 @@
 (defn ^DB empty-db
   ([] (empty-db default-schema))
   ([schema]
+    {:pre [(or (nil? schema) (map? schema))]}
     (map->DB {
       :schema  (validate-schema schema)
       :eavt    (btset/btset-by cmp-datoms-eavt)
@@ -658,6 +662,7 @@
   (is-attr? db attr :db/isComponent))
 
 (defn entid [db eid]
+  {:pre [(db? db)]}
   (cond
     (number? eid) eid
     (sequential? eid)

src/datascript/impl/entity.cljc

@@ -11,9 +11,7 @@
     (dc/entid db eid)))
 
 (defn entity [db eid]
-  {:pre [(satisfies? dc/IDB db)
-         (satisfies? dc/ISearch db)
-         (satisfies? dc/IIndexAccess db)]}
+  {:pre [(dc/db? db)]}
   (when-let [e (entid db eid)]
     (->Entity db e (volatile! false) (volatile! {}))))
 
@@ -189,6 +187,7 @@
     {} (partition-by :a datoms)))
 
 (defn touch [^Entity e]
+  {:pre [(entity? e)]}
   (when-not @(.-touched e)
     (when-let [datoms (not-empty (dc/-search (.-db e) [(.-eid e)]))]
       (vreset! (.-cache e) (->> datoms

src/datascript/pull_api.cljc

@@ -268,10 +268,10 @@
   (let [eids (into [] (map #(dc/entid-strict db %)) eids)]
     (pull-pattern db (list (initial-frame pattern eids multi?)))))
 
-(defn pull
-  [db selector eid]
+(defn pull [db selector eid]
+  {:pre [(dc/db? db)]}
   (pull-spec db (dpp/parse-pull selector) [eid] false))
 
-(defn pull-many
-  [db selector eids]
+(defn pull-many [db selector eids]
+  {:pre [(dc/db? db)]}
   (pull-spec db (dpp/parse-pull selector) eids true))