Ragtime migrations adapter

ChangeLog.md

@@ -1,5 +1,24 @@
 ## Changes between 1.0.0-rc1 and 1.0.0-rc2
 
+### Ragtime integration
+
+Monger now provides an adapter for [Ragtime, a generic Clojure library for data migrations](https://github.com/weavejester/ragtime) (evolutions).
+
+It is in the `monger.ragtime` namespace. To use Ragtime with Monger, you need to add dependencies
+on both Ragtime core and Monger to your project. An example with Leiningen:
+
+``` clojure
+:dependencies [[org.clojure/clojure       "1.4.0"]
+               [com.novemberain/monger    "1.0.0-rc2"]
+               [ragtime/ragtime.core      "0.2.0"]]
+```
+
+Then require `monger.ragtime` and use Ragtime as usual, passing it a database instance
+you get via `monger.core/get-db`.
+
+Monger will persist information about migrations using the `FSYNC_SAFE` write concern.
+
+
 ### Query DSL no longer seq()s the cursor
 
 Query DSL will no longer apply `clojure.core/seq` to the underlying cursor, thus guaranteeing to return an empty

project.clj

@@ -5,7 +5,8 @@
   :dependencies [[org.clojure/clojure           "1.3.0"]
                  [org.mongodb/mongo-java-driver "2.7.3"]
                  [com.novemberain/validateur    "1.1.0"]
-                 [clojurewerkz/support          "0.5.0"]]
+                 [clojurewerkz/support          "0.5.0"]
+                 [ragtime/ragtime.core          "0.2.0" :exclusions [org.clojure/clojure]]]
   :test-selectors {:default     (fn [m]
                                   (and (not (:performance m))
                                        (not (:edge-features m))))

src/clojure/monger/ragtime.clj

@@ -0,0 +1,34 @@
+(ns monger.ragtime
+  (:refer-clojure :exclude [find sort])
+  (:require [ragtime.core      :as ragtime]
+            [monger.core       :as mg]
+            [monger.collection :as mc])
+  (:use [monger.query :only [with-collection find sort]])
+  (:import java.util.Date
+           [com.mongodb DB WriteConcern]))
+
+
+(def ^{:const true}
+  migrations-collection "meta.migrations")
+
+
+
+(extend-type com.mongodb.DB
+  ragtime/Migratable
+  (add-migration-id [db id]
+    (mc/insert db migrations-collection {:_id id :created_at (Date.)} WriteConcern/FSYNC_SAFE))
+  (remove-migration-id [db id]
+    (mc/remove-by-id db migrations-collection id))
+  (applied-migration-ids [db]
+    (mg/with-db db
+      (let [xs (with-collection migrations-collection
+                 (find {})
+                 (sort {:created_at 1}))]
+        (set (map :_id xs))))))
+
+
+(defn flush-migrations!
+  "REMOVES all the information about previously performed migrations"
+  [db]
+  (mg/with-db db
+    (mc/remove migrations-collection)))

test/monger/test/fixtures.clj

@@ -17,3 +17,4 @@
 
 (defcleaner cached    "cached")
 
+(defcleaner migrations "meta.migrations")

test/monger/test/ragtime_test.clj

@@ -0,0 +1,37 @@
+(set! *warn-on-reflection* true)
+
+(ns monger.test.ragtime-test
+  (:require [monger.core :as mg]
+            [monger.collection  :as mc]
+            [monger.test.helper :as helper]
+            monger.ragtime)
+  (:use clojure.test
+        [monger.test.fixtures :only [purge-migrations]]
+        ragtime.core))
+
+
+(helper/connect!)
+
+(use-fixtures :each purge-migrations)
+
+
+(deftest test-add-migration-id
+  (let [db   (mg/get-db "monger-test")
+        coll "meta.migrations"
+        key  "1"]
+    (is (not (mc/any? db coll {:_id key})))
+    (is (not (contains? (applied-migration-ids db) key)))
+    (add-migration-id db key)
+    (is (mc/any? db coll {:_id key}))
+    (is (contains? (applied-migration-ids db) key))))
+
+
+(deftest test-remove-migration-id
+  (let [db   (mg/get-db "monger-test")
+        coll "meta.migrations"
+        key  "1"]
+    (add-migration-id db key)
+    (is (mc/any? db coll {:_id key}))
+    (is (contains? (applied-migration-ids db) key))
+    (remove-migration-id db key)
+    (is (not (contains? (applied-migration-ids db) key)))))