Add monger.collection/find-and-modify and associated tests.

src/monger/collection.clj

@@ -172,6 +172,42 @@
      (from-db-object ^DBObject (find-one collection ref fields) keywordize)))
 
 
+;;
+;; monger.collection/find-and-modify
+;;
+
+(defn ^DBObject find-and-modify
+  "Atomically modify a document (at most one) and return it.
+
+   EXAMPLES:
+      
+      ;; Find and modify a document
+      (mgcol/find-and-modify collection { :language \"Python\" } { :language \"Clojure\" })
+
+      ;; If multiple documents match, choose the first one in the specified order
+      (mgcol/find-and-modify collection { :language \"Python\" } { :language \"Clojure\" } :sort { :language -1 })
+
+      ;; Remove the object before returning
+      (mgcol/find-and-modify collection { :language \"Python\" } {} :remove true)
+
+      ;; Return the modified object instead of the old one
+      (mgcol/find-and-modify collection { :language \"Python\" } { :language \"Clojure\" } :return-new true)
+
+      ;; Retrieve a subset of fields
+      (mgcol/find-and-modify collection { :language \"Python\" } { :language \"Clojure\" } :fields [ :language ])
+
+      ;; Create the object if it doesn't exist
+      (mgcol/find-and-modify collection { :language \"Factor\" } { :language \"Clojure\" } :upsert true)
+
+  "
+  ([^String collection ^Map conditions ^Map document & { :keys [fields sort remove return-new upsert keywordize] :or
+                                                       { fields nil sort nil remove false return-new false upsert false keywordize true }}]
+     (let [^DBCollection coll (.getCollection monger.core/*mongodb-database* collection)
+           maybe-fields (when fields (to-db-object (as-field-selector fields)))
+           maybe-sort (when sort (to-db-object sort))]
+       (from-db-object
+        ^DBObject (.findAndModify ^DBCollection coll ^DBObject (to-db-object conditions) maybe-fields maybe-sort remove
+                                  ^DBObject (to-db-object document) return-new upsert) keywordize))))
 
 ;;
 ;; monger.collection/find-by-id

test/monger/test/atomic_modifiers_test.clj

@@ -291,3 +291,50 @@
     (mgcol/insert coll { :_id oid :title title :measurements v })
     (mgcol/update coll { :_id oid } { $rename { :measurements "results" } })
     (is (= { :_id oid :title title :results v } (mgcol/find-map-by-id coll oid)))))
+
+
+;;
+;; find-and-modify
+;;
+
+(deftest find-and-modify-a-single-document
+  (let [coll "docs"
+        oid (ObjectId.)
+        doc {:_id oid :name "Sophie Bangs" :level 42}
+        conditions {:name "Sophie Bangs"}
+        update {$inc {:level 1}}]
+    (mgcol/insert coll doc)
+    (let [res (mgcol/find-and-modify coll conditions update :return-new true)]
+      (is (= (select-keys res [:name :level]) {:name "Sophie Bangs" :level 43})))))
+
+
+(deftest find-and-modify-remove-a-document
+  (let [coll "docs"
+        oid (ObjectId.)
+        doc {:_id oid :name "Sophie Bangs" :level 42}
+        conditions {:name "Sophie Bangs"}]
+    (mgcol/insert coll doc)
+    (let [res (mgcol/find-and-modify coll conditions {} :remove true)]
+      (is (= (select-keys res [:name :level]) {:name "Sophie Bangs" :level 42}))
+      (is (empty? (mgcol/find-maps coll conditions))))))
+
+
+(deftest find-and-modify-upsert-a-document
+  (let [coll "docs"
+        oid (ObjectId.)
+        doc {:_id oid :name "Sophie Bangs" :level 42}]
+    (let [res (mgcol/find-and-modify coll doc doc :upsert true)]
+      (is (empty? res))
+      (is (select-keys (mgcol/find-map-by-id coll oid) [:name :level]) (dissoc doc :_id)))))
+
+
+(deftest find-and-modify-after-sort
+  (let [coll "docs"
+        oid (ObjectId.)
+        oid2 (ObjectId.)
+        doc {:name "Sophie Bangs"}
+        doc1 (assoc doc :_id oid :level 42)
+        doc2 (assoc doc :_id oid2 :level 0)]
+    (mgcol/insert-batch coll [doc1 doc2])
+    (let [res (mgcol/find-and-modify coll doc {$inc {:level 1}} :sort {:level -1})]
+      (is (= (select-keys res [:name :level]) {:name "Sophie Bangs" :level 42})))))