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Tidy up some mongo<->clojure coercion code using multimethods

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1 parent 149b1b9 commit 7e7405c380759a38e0930593bbfbb7ef95ad7198 @purcell committed Jan 26, 2010
Showing with 40 additions and 24 deletions.
  1. +40 −24 src/clj/somnium/congomongo/coerce.clj
@@ -13,53 +13,69 @@
"Set this to false to prevent ClojureDBObject from setting string keys to keywords")
-(declare obj->clojure)
+;;; Converting data from mongo into Clojure data objects
+(defn- mongo->clojure-dispatch [o keywordize]
+ (class o))
+(defmulti mongo->clojure mongo->clojure-dispatch)
(defn- assocs->clojure [kvs keywordize]
;; Taking the keywordize test out of the fn reduces derefs
;; dramatically, which was the main barrier to matching pure-Java
;; performance for this marshalling
(reduce (if keywordize
- (fn [m [#^String k v]] (assoc m (keyword k) (obj->clojure v true)))
- (fn [m [#^String k v]] (assoc m k (obj->clojure v false))))
+ (fn [m [#^String k v]] (assoc m (keyword k) (mongo->clojure v true)))
+ (fn [m [#^String k v]] (assoc m k (mongo->clojure v false))))
{} kvs))
-(defn- map->clojure [#^Map m keywordize]
+(defmethod mongo->clojure Map
+ [#^Map m keywordize]
(assocs->clojure (.entrySet m) keywordize))
-(defn- list->clojure [#^List l keywordize]
- (vec (map #(obj->clojure % keywordize) l)))
+(defmethod mongo->clojure List
+ [#^List l keywordize]
+ (vec (map #(mongo->clojure % keywordize) l)))
-(defn- obj->clojure [o keywordize]
- (cond
- (.isInstance Map o) (map->clojure o keywordize)
- (.isInstance List o) (list->clojure o keywordize)
- true o))
+(defmethod mongo->clojure :default
+ [o keywordize]
+ o)
-(defn- dbobject->clojure
+(defmethod mongo->clojure DBObject
[#^DBObject f keywordize]
;; DBObject provides .toMap, but the implementation in
;; subclass GridFSFile unhelpfully throws
;; UnsupportedOperationException
(assocs->clojure (for [k (.keySet f)] [k (.get f k)]) keywordize))
+(prefer-method mongo->clojure DBObject Map)
+;;; Converting data from Clojure into data objects suitable for Mongo
-(declare clojure-obj->mongo-obj)
+(defmulti clojure->mongo class)
-(defn- clojure-map->mongo-map [#^IPersistentMap m]
+(defmethod clojure->mongo IPersistentMap
+ [#^IPersistentMap m]
(let [dbo (BasicDBObject.)]
(doseq [[k v] m]
(.put dbo
(if (keyword? k) (.getName #^Keyword k) k)
- (clojure-obj->mongo-obj v)))
+ (clojure->mongo v)))
-(defn- clojure-obj->mongo-obj [o]
- (cond
- (keyword? o) (.getName #^Keyword o)
- (map? o) (clojure-map->mongo-map #^IPersistentMap o)
- (.isInstance List o) (map clojure-obj->mongo-obj #^List o)
- true o))
+(defmethod clojure->mongo Keyword
+ [#^Keyword o]
+ (.getName o))
+(defmethod clojure->mongo List
+ [#^List o]
+ (map clojure->mongo o))
+(defmethod clojure->mongo :default
+ [o]
+ o)
(defunk coerce
@@ -74,11 +90,11 @@
(let [fun
(condp = from-to
- [:clojure :mongo ] clojure-map->mongo-map
+ [:clojure :mongo ] clojure->mongo
[:clojure :json ] json-str
- [:mongo :clojure] #(dbobject->clojure #^DBObject % #^Boolean/TYPE *keywordize*)
+ [:mongo :clojure] #(mongo->clojure #^DBObject % #^Boolean/TYPE *keywordize*)
[:mongo :json ] #(.toString #^DBObject %)
- [:gridfs :clojure] #(dbobject->clojure #^GridFSFile % *keywordize*)
+ [:gridfs :clojure] #(mongo->clojure #^GridFSFile % *keywordize*)
[:json :clojure] #(binding [*json-keyword-keys* *keywordize*] (read-json %))
[:json :mongo ] #(JSON/parse %)
:else (throw (RuntimeException.

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