CongoMongo

What?

A toolkit for using MongoDB with Clojure.

Recent Changes

Added a few convenience fns related to object-ids:

'object-id: creates a com.mongodb.ObjectId from a string so
you don't have to import it anymore.

'fetch-by-id: takes a collection and a string/object-id and
fetches the result

'get-timestamp: takes a map with a valid :_id or an ObjectId and returns the embedded timestamp

GridFs support courtesy of Steve Purcell.

Bumped version to 0.1.2.

Clojars group is now congomongo.

Summary

note: The .java bits are likely to disappear once Clojure 1.2 is stable.

CongoMongo is essentially two parts.

One is the ClojureDBObject class written in java. It extends the BasicDBObject class with two methods (putClojure, toClojure) and a convenience constructor.

It is basically a close-to-the-metal wrapper around the mongo-java-driver's BasicDBObject class to handle coercions (keyword->string and nested structures)
while offering similar performance to the BasicDBObject class itself.

The rest is a Clojure api for the mongo-java-driver.

Basics

Setup

(ns my-mongo-app  
  (:use somnium.congomongo))  
(mongo!  
  :db "mydb") 

Simple Tasks

---

create

(insert! :robots    
         {:name "robby"}

read

(def my-robot (fetch-one :robots)) => #'user/my-robot

my-robot => { :name "robby", 
              :_id  #<ObjectId> "0c23396f7e53e34a4c8cf400">, 
              :_ns  "robots"}

update

(update! :robots my-robot (merge my-robot { :name "asimo" }))

=>  { :name "asimo" , 
      :_id  #<ObjectId> "0c23396f7e53e34a4c8cf400"> , 
      :_ns : "robots" }

destroy

(destroy! my-robot) => nil
(fetch :robots) => ()

More Sophisticated Tasks

---

mass inserts

(mass-insert!  
  :points
  (for [x (range 100) y (range 100)] 
    {:x x 
     :y y 
     :z (* x y)})) 

 =>  nil

(fetch-count :points)
=> 10000

ad-hoc queries

(fetch-one
  :points
  :where {:x {:$gt 10  
              :$lt 20}
          :y 42
          :z {:$gt 500}})

=> {:x 12, :y 42, :z 504,  :_ns "points", :_id ... }

easy json

---

(fetch-one :points 
           :as :json)

=> "{ \"_id\" : \"0c23396ffe79e34a508cf400\" , 
      \"x\" : 0 , \"y\" : 0 , \"z\" : 0 , \"_ns\" : \"points\"}"

Install

Leiningen is the recommended way to use congomongo. Just add [congomongo "0.1.2-SNAPSHOT"] to your project.clj and do $lein deps to get congomongo and all of its dependencies.

TODO

• convenient dsl for advanced queries/features
• orm-like schemas/validations?

Feedback

CongoMongo is a work in progress. If you've used, improved, or abused it I'd love to hear about it. Contact me at boekhoffa@gmail.com