Merge branch 'master' of https://github.com/michaelklishin/monger

README.md

@@ -1,6 +1,7 @@
 # Monger
 
-Monger is an idiomatic Clojure wrapper around MongoDB Java driver.
+Monger is an idiomatic Clojure wrapper around MongoDB Java driver. It offers powerful expressive query DSL, strives to support
+every MongoDB 2.0+ feature and is well maintained.
 
 
 ## Project Goals
@@ -17,11 +18,18 @@ wanted a client that will
  * Learn from other clients like the Java and Ruby ones.
  * Target Clojure 1.3.0 and later from the ground up.
 
+
 ## Usage
 
-We are working on documentation guides & examples site for the 1.0 release. Please refer to the test suite for code examples.
+We are working on documentation guides & examples site for the 1.0 release. In the meantime, please refer to the [test suite](https://github.com/michaelklishin/monger/tree/master/test/monger/test) for code examples.
 
-Here is what monger.query DSL looks like right now:
+
+## Powerful Query DSL
+
+Every application that works with data stores has to query them. As a consequence, having an expressive powerful query DSL is a must
+for client libraries like Monger.
+
+Here is what monger.query DSL feels like:
 
 ``` clojure
 (with-collection "docs"
@@ -34,12 +42,38 @@ Here is what monger.query DSL looks like right now:
   (snapshot))
 ```
 
-More code examples can be found in our test suite.
+It is easy to add new DSL elements, for example, adding pagination took literally less than 10 lines of Clojure code. Here is what
+it looks like:
+
+``` clojure
+(with-collection coll
+                  (find {})
+                  (paginate :page 1 :per-page 3)
+                  (sort { :title 1 })
+                  (read-preference ReadPreference/PRIMARY))
+```
+
+Query DSL supports composition, too:
+
+``` clojure
+(let
+    [top3               (partial-query (limit 3))
+     by-population-desc (partial-query (sort { :population -1 }))
+     result             (with-collection coll
+                          (find {})
+                          (merge top3)
+                          (merge by-population-desc))]
+  ;; ...
+  )
+```
+
+More code examples can be found [in our test suite](https://github.com/michaelklishin/monger/tree/master/test/monger/test).
 
 
 ## This is a Work In Progress
 
-Core Monger APIs are stabilized but it is still a work in progress. Keep that in mind. 1.0 will be released in late 2011.
+Core Monger APIs are stabilized but it is still a work in progress. Keep that in mind. 1.0 will be released in early 2012
+together with documentation guides and dedicated website.
 
 
 ## Artifacts
@@ -48,7 +82,7 @@ Snapshot artifacts are [released to Clojars](https://clojars.org/com.novemberain
 
 With Leiningen:
 
-    [com.novemberain/monger "0.11.0-SNAPSHOT"]
+    [com.novemberain/monger "1.0.0-SNAPSHOT"]
 
 
 With Maven:
@@ -56,7 +90,7 @@ With Maven:
     <dependency>
       <groupId>com.novemberain</groupId>
       <artifactId>monger</artifactId>
-      <version>0.11.0-SNAPSHOT</version>
+      <version>1.0.0-SNAPSHOT</version>
     </dependency>
 
 
@@ -65,7 +99,7 @@ With Maven:
 [![Continuous Integration status](https://secure.travis-ci.org/michaelklishin/monger.png)](http://travis-ci.org/michaelklishin/monger)
 
 
-CI is hosted by [travis-ci.org](http://travis-ci.org)
+CI is hosted by [travis-ci.org](http://travis-ci.org).
 
 
 

src/monger/collection.clj

@@ -8,7 +8,7 @@
 ;; You must not remove this notice, or any other, from this software.
 
 (ns monger.collection
-  (:refer-clojure :exclude [find remove count drop distinct])
+  (:refer-clojure :exclude [find remove count drop distinct empty?])
   (:import [com.mongodb Mongo DB DBCollection WriteResult DBObject WriteConcern DBCursor MapReduceCommand MapReduceCommand$OutputType]
            [java.util List Map]
            [clojure.lang IPersistentMap ISeq])

src/monger/conversion.clj

@@ -22,9 +22,10 @@
 ;; THE SOFTWARE.
 
 (ns monger.conversion
-  (:import (com.mongodb DBObject BasicDBObject BasicDBList DBCursor)
+  (:import [com.mongodb DBObject BasicDBObject BasicDBList DBCursor]
-           (clojure.lang IPersistentMap Keyword)
+           [clojure.lang IPersistentMap Keyword]
-           (java.util List Map)))
+           [java.util List Map Date]
+           [org.bson.types ObjectId]))
 
 (defprotocol ConvertToDBObject
   (to-db-object [input] "Converts given piece of Clojure data to BasicDBObject MongoDB Java driver uses"))
@@ -101,3 +102,22 @@
               (assoc m k (from-db-object v false))))
           {} (reverse pairs)))
 
+
+
+(defprotocol ConvertToObjectId
+  (to-object-id [input] "Instantiates ObjectId from input unless the input itself is an ObjectId instance. In that case, returns input as is."))
+
+(extend-protocol ConvertToObjectId
+  String
+  (to-object-id [^String input]
+    (ObjectId. input))
+
+  Date
+  (to-object-id [^Date input]
+    (ObjectId. input))
+
+  ObjectId
+  (to-object-id [^ObjectId input]
+    input))
+
+

src/monger/core.clj

@@ -14,8 +14,9 @@
   monger.core
   (:refer-clojure :exclude [count])
   (:use [monger.conversion])
-  (:import (com.mongodb Mongo DB WriteConcern DBObject DBCursor)
+  (:import [com.mongodb Mongo DB WriteConcern DBObject DBCursor CommandResult]
-           (java.util Map)))
+           [com.mongodb.gridfs GridFS]
+           [java.util Map]))
 
 ;;
 ;; Defaults
@@ -28,6 +29,7 @@
 (declare ^:dynamic ^DB           *mongodb-database*)
 (def     ^:dynamic ^WriteConcern *mongodb-write-concern* WriteConcern/SAFE)
 
+(declare ^:dynamic ^GridFS       *mongodb-gridfs*)
 
 ;;
 ;; API
@@ -75,33 +77,37 @@
   `(binding [*mongodb-database* ~db]
      (do ~@body)))
 
+(defmacro with-gridfs
+  [fs & body]
+  `(binding [*mongodb-gridfs* ~fs]
+     (do ~@body)))
+
 
 (defn connect!
-  "Connect to MongoDB, save connection to *mongodb-connection* dynamic variable"
+  "Connect to MongoDB, store connection in the *mongodb-connection* var"
   ^Mongo [& args]
   (def ^:dynamic *mongodb-connection* (apply connect args)))
 
 
 (defn set-db!
-  "Set dynamic *mongodb-database* variable to given :db"
+  "Sets *mongodb-database* var to given db, updates *mongodb-gridfs* var state. Recommended to be used for
+  applications that only use one database."
   [db]
-  (def ^:dynamic *mongodb-database* db))
+  (def ^:dynamic *mongodb-database* db)
+  (def ^:dynamic *mongodb-gridfs* (GridFS. db)))
 
 
 (defn set-default-write-concern!
   [wc]
-  "Set dynamic *mongodb-write-concert* to :wc
+  "Set *mongodb-write-concert* var to :wc
 
-  We recommend to use WriteConcern/SAFE by default to make sure your data was written."
+  Unlike the official Java driver, Monger uses WriteConcern/SAFE by default. We think defaults should be safe first
+  and WebScale fast second."
   (def ^:dynamic *mongodb-write-concern* wc))
 
-(defn command
+(defn ^CommandResult command
-  "Available commands (please check MongoDB documentation for a complete list of commands for particular DB version.
+  "Runs a database command (please check MongoDB documentation for the complete list of commands). Some common commands
-   Returns CommandResult.
+  are:
-     Use (.ok result) to get response status.
-     It implements AbstractMap interface, so you can access it's internals:
-
-        (get (monger.core/command { :collstats \"things\") \"ns\")) ;; => monger-test.things
 
    { :buildinfo 1 } returns version number and build information about the current MongoDB server, should be executed via admin DB.
 
@@ -162,7 +168,7 @@
 
 (extend-protocol Countable
   DBCursor
-  (count [^com.mongodb.DBCursor this]
+  (count [^DBCursor this]
     (.count this)))
 
 (defn ^DBObject get-last-error
@@ -184,5 +190,3 @@
      (.getLastError ^DB database w wtimeout fsync))
   ([^DB database ^WriteConcern write-concern]
      (.getLastError ^DB database write-concern)))
-
-

src/monger/gridfs.clj

@@ -0,0 +1,100 @@
+(ns monger.gridfs
+  (:refer-clojure :exclude [remove find])
+  (:require [monger.core]
+            [clojure.java.io :as io])
+  (:use [monger.conversion])
+  (:import [com.mongodb DBObject]
+           [com.mongodb.gridfs GridFS GridFSInputFile]
+           [java.io InputStream File]))
+
+;;
+;; Implementation
+;;
+
+(def
+  ^{:doc "Type object for a Java primitive byte array."
+    :private true
+    }
+  byte-array-type (class (make-array Byte/TYPE 0)))
+
+;; ...
+
+
+
+;;
+;; API
+;;
+
+
+(defn remove
+  ([]
+     (remove {}))
+  ([query]
+     (.remove ^GridFS monger.core/*mongodb-gridfs* ^DBObject (to-db-object query))))
+
+(defn remove-all
+  []
+  (remove {}))
+
+(defn all-files
+  ([]
+     (.getFileList ^GridFS monger.core/*mongodb-gridfs*))
+  ([query]
+     (.getFileList ^GridFS monger.core/*mongodb-gridfs* query)))
+
+
+(defprotocol GridFSInputFileFactory
+  (^GridFSInputFile make-input-file [input] "Makes GridFSInputFile out of given input"))
+
+(extend byte-array-type
+  GridFSInputFileFactory
+  { :make-input-file (fn [^bytes input]
+                       (.createFile ^GridFS monger.core/*mongodb-gridfs* input)) })
+
+(extend-protocol GridFSInputFileFactory
+  String
+  (make-input-file [^String input]
+    (.createFile ^GridFS monger.core/*mongodb-gridfs* ^InputStream (io/make-input-stream input { :encoding "UTF-8" })))
+
+  File
+  (make-input-file [^File input]
+    (.createFile ^GridFS monger.core/*mongodb-gridfs* ^InputStream (io/make-input-stream input { :encoding "UTF-8" })))
+
+  InputStream
+  (make-input-file [^InputStream input]
+    (.createFile ^GridFS monger.core/*mongodb-gridfs* ^InputStream input)))
+
+
+(defmacro store
+  [^GridFSInputFile input & body]
+  `(let [^GridFSInputFile f# (doto ~input ~@body)]
+     (.save f# GridFS/DEFAULT_CHUNKSIZE)
+     (from-db-object f# true)))
+
+
+(defprotocol Finders
+  (find     [input] "Finds multiple files using given input (an ObjectId, filename or query)")
+  (find-one [input] "Finds one file using given input (an ObjectId, filename or query)"))
+
+(extend-protocol Finders
+  String
+  (find [^String input]
+    (vec (.find ^GridFS monger.core/*mongodb-gridfs* input)))
+  (find-one [^String input]
+    (.findOne ^GridFS monger.core/*mongodb-gridfs* input))
+
+  org.bson.types.ObjectId
+  (find-one [^org.bson.types.ObjectId input]
+    (.findOne ^GridFS monger.core/*mongodb-gridfs* input))
+
+
+  DBObject
+  (find [^DBObject input]
+    (vec (.find ^GridFS monger.core/*mongodb-gridfs* input)))
+  (find-one [^DBObject input]
+    (.findOne ^GridFS monger.core/*mongodb-gridfs* input))
+
+  clojure.lang.PersistentArrayMap
+  (find [^clojure.lang.PersistentArrayMap input]
+    (find (to-db-object input))))
+

src/monger/query.clj

@@ -2,7 +2,7 @@
   (:refer-clojure :exclude [select find sort])
   (:require [monger.core]
             [monger.internal pagination])
-  (:import [com.mongodb DB DBCollection DBObject DBCursor]
+  (:import [com.mongodb DB DBCollection DBObject DBCursor ReadPreference]
            [java.util List])
   (:use [monger conversion operators]))
 
@@ -34,9 +34,8 @@
 ;;    deleted during the query, it may or may not be returned, even with snapshot mode). Note that short query responses
 ;;    (less than 1MB) are always effectively snapshotted. Currently, snapshot mode may not be used with sorting or explicit hints.
 (defn empty-query
-  [^DBCollection coll]
+  ([]
      {
-   :collection      coll
       :query           {}
       :sort            {}
       :fields          []
@@ -46,22 +45,25 @@
       :hint            nil
       :snapshot        false
       })
+  ([^DBCollection coll]
+     (merge (empty-query) { :collection coll })))
 
 (defn- fields-to-db-object
   [^List fields]
   (to-db-object (zipmap fields (repeat 1))))
 
 (defn exec
-  [{ :keys [collection query fields skip limit sort batch-size hint snapshot] :or { limit 0 batch-size 256 skip 0 } }]
+  [{ :keys [collection query fields skip limit sort batch-size hint snapshot read-preference] :or { limit 0 batch-size 256 skip 0 } }]
   (let [cursor (doto ^DBCursor (.find ^DBCollection collection (to-db-object query) (fields-to-db-object fields))
                      (.limit limit)
                      (.skip  skip)
                      (.sort  (to-db-object sort))
                      (.batchSize batch-size)
-                     (.hint ^DBObject (to-db-object hint))
+                     (.hint ^DBObject (to-db-object hint)))]
-                     )]
+    (when snapshot
-    (if snapshot
       (.snapshot cursor))
+    (when read-preference
+      (.setReadPreference cursor read-preference))
     (map (fn [x] (from-db-object x true))
          (seq cursor))))
 
@@ -101,6 +103,10 @@
   [m]
   (merge m { :snapshot true }))
 
+(defn read-preference
+  [m ^ReadPreference rp]
+  (merge m { :read-preference rp }))
+
 (defn paginate
   [m & { :keys [page per-page] :or { page 1 per-page 10 } }]
   (merge m { :limit per-page :skip (monger.internal.pagination/offset-for page per-page) }))
@@ -112,3 +118,7 @@
                                   ~coll)]
      (let [query# (-> (empty-query *query-collection*) ~@body)]
        (exec query#))))
+
+(defmacro partial-query
+  [& body]
+  `(-> {} ~@body))

test/monger/test/atomic_modifiers.clj

@@ -3,9 +3,7 @@
 (ns monger.test.atomic-modifiers
   (:import  [com.mongodb WriteResult WriteConcern DBCursor DBObject CommandResult$CommandFailure]
             [org.bson.types ObjectId]
-            [java.util Date]
+            [java.util Date])
-
-            )
   (:require [monger core util]
             [monger.collection :as mgcol]
             [monger.result     :as mgres]

test/monger/test/collection.clj

@@ -130,9 +130,9 @@
 (deftest find-one-full-document-when-collection-has-matches
   (let [collection "docs"
         doc-id     (monger.util/random-uuid)
-        doc        { :data-store "MongoDB", :language "Clojure", :_id doc-id }]
+        doc        { :data-store "MongoDB", :language "Clojure", :_id doc-id }
-    (mgcol/insert collection doc)
+        _          (mgcol/insert collection doc)
-    (def ^DBObject found-one (mgcol/find-one collection { :language "Clojure" }))
+        found-one (mgcol/find-one collection { :language "Clojure" })]
     (is (= (:_id doc) (monger.util/get-id found-one)))
     (is (= (mgcnv/from-db-object found-one true) doc))
     (is (= (mgcnv/to-db-object doc) found-one))))
@@ -150,9 +150,9 @@
   (let [collection "docs"
         doc-id     (monger.util/random-uuid)
         doc        { :data-store "MongoDB", :language "Clojure", :_id doc-id }
-        fields     [:language]]
+        fields     [:language]
-    (mgcol/insert collection doc)
+        _          (mgcol/insert collection doc)
-    (def ^DBObject loaded (mgcol/find-one collection { :language "Clojure" } fields))
+        loaded     (mgcol/find-one collection { :language "Clojure" } fields)]
     (is (nil? (.get ^DBObject loaded "data-store")))
     (is (= doc-id (monger.util/get-id loaded)))
     (is (= "Clojure" (.get ^DBObject loaded "language")))))

test/monger/test/conversion.clj

@@ -2,7 +2,8 @@
   (:require [monger core collection]
             [monger.conversion :as cnv])
   (:import [com.mongodb DBObject BasicDBObject BasicDBList]
-           [java.util Date Calendar List ArrayList])
+           [java.util Date Calendar List ArrayList]
+           [org.bson.types ObjectId])
   (:use [clojure.test]))
 
 
@@ -131,3 +132,13 @@
     (is (= (-> output (get "nested") (get "list")) ["red" "green" "blue"]))
     (is (= (-> output (get "nested") (get "dblist")) [0 1]))))
 
+
+
+;;
+;; ObjectId coercion
+;;
+
+(deftest test-conversion-to-object-id
+  (let [output (ObjectId. "4efb39370364238a81020502")]
+    (is (= output (cnv/to-object-id "4efb39370364238a81020502")))
+    (is (= output (cnv/to-object-id output)))))

test/monger/test/gridfs.clj

@@ -0,0 +1,130 @@
+(ns monger.test.gridfs
+  (:refer-clojure :exclude [count remove find])
+  (:use [clojure.test]
+        [monger.core :only [count]]
+        [monger.test.fixtures]
+        [monger operators conversion]
+        [monger.gridfs :only (store make-input-file)])
+  (:require [monger.gridfs :as gridfs]
+            [monger.test.helper :as helper]
+            [clojure.java.io :as io])
+  (:import [java.io InputStream File FileInputStream]
+           [com.mongodb.gridfs GridFS GridFSInputFile GridFSDBFile]))
+
+
+(defn purge-gridfs
+  [f]
+  (gridfs/remove-all)
+  (f)
+  (gridfs/remove-all))
+
+(use-fixtures :each purge-gridfs)
+
+(helper/connect!)
+
+
+
+(deftest test-storing-files-to-gridfs-using-relative-fs-paths
+  (let [input "./test/resources/mongo/js/mapfun1.js"]
+    (is (= 0 (count (gridfs/all-files))))
+    (store (make-input-file input)
+      (.setFilename "monger.test.gridfs.file1")
+      (.setContentType "application/octet-stream"))
+    (is (= 1 (count (gridfs/all-files))))))
+
+
+(deftest test-storing-files-to-gridfs-using-file-instances
+  (let [input (io/as-file "./test/resources/mongo/js/mapfun1.js")]
+    (is (= 0 (count (gridfs/all-files))))
+    (store (make-input-file input)
+      (.setFilename "monger.test.gridfs.file2")
+      (.setContentType "application/octet-stream"))
+    (is (= 1 (count (gridfs/all-files))))))
+
+(deftest test-storing-bytes-to-gridfs
+  (let [input (.getBytes "A string")]
+    (is (= 0 (count (gridfs/all-files))))
+    (store (make-input-file input)
+      (.setFilename "monger.test.gridfs.file3")
+      (.setContentType "application/octet-stream"))
+    (is (= 1 (count (gridfs/all-files))))))
+
+(deftest test-storing-files-to-gridfs-using-absolute-fs-paths
+  (let [tmp-file (File/createTempFile "monger.test.gridfs" "test-storing-files-to-gridfs-using-absolute-fs-paths")
+        _        (spit tmp-file "Some content")
+        input    (.getAbsolutePath tmp-file)]
+    (is (= 0 (count (gridfs/all-files))))
+    (store (make-input-file input)
+      (.setFilename "monger.test.gridfs.file4")
+      (.setContentType "application/octet-stream"))
+    (is (= 1 (count (gridfs/all-files))))))
+
+(deftest test-storing-files-to-gridfs-using-input-stream
+  (let [tmp-file (File/createTempFile "monger.test.gridfs" "test-storing-files-to-gridfs-using-input-stream")
+        _        (spit tmp-file "Some other content")]
+    (is (= 0 (count (gridfs/all-files))))
+    (store (make-input-file (FileInputStream. tmp-file))
+      (.setFilename "monger.test.gridfs.file4b")
+      (.setContentType "application/octet-stream"))
+    (is (= 1 (count (gridfs/all-files))))))
+
+
+
+(deftest test-finding-individual-files-on-gridfs
+  (let [input   "./test/resources/mongo/js/mapfun1.js"
+        ct      "binary/octet-stream"
+        filename "monger.test.gridfs.file5"
+        md5      "14a09deabb50925a3381315149017bbd"
+        stored  (store (make-input-file input)
+                  (.setFilename filename)
+                  (.setContentType ct))]
+    (is (= 1 (count (gridfs/all-files))))
+    (is (:_id stored))
+    (is (:uploadDate stored))
+    (is (= 62 (:length stored)))
+    (is (= md5 (:md5 stored)))
+    (is (= filename (:filename stored)))
+    (is (= ct (:contentType stored)))
+    (are [a b] (is (= a (:md5 (from-db-object (gridfs/find-one b) true))))
+         md5 (:_id stored)
+         md5 filename
+         md5 (to-db-object { :md5 md5 }))))
+
+(deftest test-finding-multiple-files-on-gridfs
+  (let [input   "./test/resources/mongo/js/mapfun1.js"
+        ct      "binary/octet-stream"
+        md5      "14a09deabb50925a3381315149017bbd"
+        stored1  (store (make-input-file input)
+                   (.setFilename "monger.test.gridfs.file6")
+                   (.setContentType ct))
+        stored2  (store (make-input-file input)
+                   (.setFilename "monger.test.gridfs.file7")
+                   (.setContentType ct))
+        list1    (gridfs/find "monger.test.gridfs.file6")
+        list2    (gridfs/find "monger.test.gridfs.file7")
+        list3    (gridfs/find "888000___.monger.test.gridfs.file")
+        list4    (gridfs/find { :md5 md5 })]
+    (is (= 2 (count (gridfs/all-files))))
+    (are [a b] (is (= (map #(.get ^GridFSDBFile % "_id") a)
+                      (map :_id b)))
+         list1 [stored1]
+         list2 [stored2]
+         list3 []
+         list4 [stored1 stored2])))
+
+
+(deftest test-removing-multiple-files-from-gridfs
+  (let [input   "./test/resources/mongo/js/mapfun1.js"
+        ct      "binary/octet-stream"
+        md5      "14a09deabb50925a3381315149017bbd"
+        stored1  (store (make-input-file input)
+                   (.setFilename "monger.test.gridfs.file8")
+                   (.setContentType ct))
+        stored2  (store (make-input-file input)
+                   (.setFilename "monger.test.gridfs.file9")
+                   (.setContentType ct))]
+    (is (= 2 (count (gridfs/all-files))))
+    (gridfs/remove { :filename "monger.test.gridfs.file8" })
+    (is (= 1 (count (gridfs/all-files))))
+    (gridfs/remove { :md5 md5 })
+    (is (= 0 (count (gridfs/all-files))))))

test/monger/test/lib_integration.clj

@@ -6,7 +6,8 @@
   (:import [org.joda.time DateTime ReadableInstant]
            [org.joda.time.format ISODateTimeFormat]
            [java.io StringWriter PrintWriter]
-           [org.bson.types ObjectId])
+           [org.bson.types ObjectId]
+           [com.mongodb DBObject])
   (:require [clojure.data.json :as json]
             [clj-time.core     :as t]))
 

test/monger/test/querying.clj

@@ -2,7 +2,7 @@
 
 (ns monger.test.querying
   (:refer-clojure :exclude [select find sort])
-  (:import  [com.mongodb WriteResult WriteConcern DBCursor DBObject CommandResult$CommandFailure]
+  (:import  [com.mongodb WriteResult WriteConcern DBCursor DBObject CommandResult$CommandFailure ReadPreference]
             [org.bson.types ObjectId]
             [java.util Date])
   (:require [monger core util]
@@ -11,7 +11,8 @@
             [monger.test.helper :as helper])
   (:use [clojure.test]
         [monger.test.fixtures]
-        [monger conversion query operators]))
+        [monger conversion query operators joda-time]
+        [clj-time.core :only [date-time]]))
 
 (helper/connect!)
 
@@ -77,7 +78,7 @@
 
 ;; < ($lt), <= ($lte), > ($gt), >= ($gte)
 
-(deftest query-using-dsl-and-$lt-operator
+(deftest query-using-dsl-and-$lt-operator-with-integers
   (let [coll "docs"
         doc1 { :language "Clojure" :_id (ObjectId.) :inception_year 2006 }
         doc2 { :language "Java"    :_id (ObjectId.) :inception_year 1992 }
@@ -86,7 +87,21 @@
         lt-result (with-collection "docs"
                     (find { :inception_year { $lt 2000 } })
                     (limit 2))]
-    (is (= [doc2] lt-result))))
+    (is (= [doc2] (vec lt-result)))))
+
+
+(deftest query-using-dsl-and-$lt-operator-with-dates
+  (let [coll "docs"
+        ;; these rely on monger.joda-time being loaded. MK.
+        doc1 { :language "Clojure" :_id (ObjectId.) :inception_year (date-time 2006 1 1) }
+        doc2 { :language "Java"    :_id (ObjectId.) :inception_year (date-time 1992 1 2) }
+        doc3 { :language "Scala"   :_id (ObjectId.) :inception_year (date-time 2003 3 3) }
+        _      (mgcol/insert-batch coll [doc1 doc2])
+        lt-result (with-collection "docs"
+                    (find { :inception_year { $lt (date-time 2000 1 2) } })
+                    (limit 2))]
+    (is (= (map :_id [doc2])
+           (map :_id (vec lt-result))))))
 
 
 
@@ -110,6 +125,20 @@
                  (find { :inception_year { "$gte" 2006 } }))))))
 
 
+(deftest query-using-$gt-$lt-$gte-$lte-operators-using-dsl-composition
+  (let [coll "docs"
+        doc1 { :language "Clojure" :_id (ObjectId.) :inception_year 2006 }
+        doc2 { :language "Java"    :_id (ObjectId.) :inception_year 1992 }
+        doc3 { :language "Scala"   :_id (ObjectId.) :inception_year 2003 }
+        srt  (-> {}
+                 (limit 1)
+                 (sort { :inception_year -1 }))
+        _    (mgcol/insert-batch coll [doc1 doc2 doc3])]
+    (is (= [doc1] (with-collection coll
+                    (find { :inception_year { "$gt"  2002 } })
+                    (merge srt))))))
+
+
 ;; $all
 
 (deftest query-with-using-$all
@@ -189,7 +218,8 @@
         result1 (with-collection coll
                   (find {})
                   (paginate :page 1 :per-page 3)
-                  (sort { :title 1 }))
+                  (sort { :title 1 })
+                  (read-preference ReadPreference/PRIMARY))
         result2 (with-collection coll
                   (find {})
                   (paginate :page 2 :per-page 3)
@@ -201,3 +231,20 @@
     (is (= [doc1 doc5 doc7] result1))
     (is (= [doc2 doc6 doc4] result2))
     (is (= [doc3] result3))))
+
+
+(deftest combined-querying-dsl-example1
+  (let [coll "docs"
+        ma-doc { :_id (ObjectId.) :name "Massachusetts" :iso "MA" :population 6547629  :joined_in 1788 :capital "Boston" }
+        de-doc { :_id (ObjectId.) :name "Delaware"      :iso "DE" :population 897934   :joined_in 1787 :capital "Dover"  }
+        ny-doc { :_id (ObjectId.) :name "New York"      :iso "NY" :population 19378102 :joined_in 1788 :capital "Albany" }
+        ca-doc { :_id (ObjectId.) :name "California"    :iso "CA" :population 37253956 :joined_in 1850 :capital "Sacramento" }
+        tx-doc { :_id (ObjectId.) :name "Texas"         :iso "TX" :population 25145561 :joined_in 1845 :capital "Austin" }
+        top3               (partial-query (limit 3))
+        by-population-desc (partial-query (sort { :population -1 }))
+        _                  (mgcol/insert-batch coll [ma-doc de-doc ny-doc ca-doc tx-doc])
+        result             (with-collection coll
+                             (find {})
+                             (merge top3)
+                             (merge by-population-desc))]
+    (is (= result [ca-doc tx-doc ny-doc]))))