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Cupboard is an embedded database library for Clojure, intended to make writing Clojure objects to disk, and retrieving them, a relatively simple task. Cupboard is almost completely schemaless, supports unique and non-unique indices, querying by one or more indices, and ACID transactional semantics.

At its lowest level, Cupboard uses Berkeley DB JE, and contains a fairly complete Clojure wrapper for the JE API. This API is available in the cupboard.bdb.je package; some projects may find this code useful on its own. The cupboard.core package provides a higher-level abstraction.

This code makes some struct-maps representing books, saves them into a database, and updates them.

(ns examples.cupboard.simple
  (:use clojure.contrib.pprint)
  (:require [cupboard.core :as cb])
  (:use [cupboard.utils]))

(cb/open-cupboard! "/tmp/books")

(cb/defpersist book
  ((:isbn :index :unique)
   (:title :index :any)
   (:author :index :any)))

(cb/make-instance book ["0393039854", "The First Folio", "Shakespeare, William"])
(cb/make-instance book ["0393925870", "The Canterbury Tales", "Chaucer"])
(cb/make-instance book ["143851557X", "Troilus and Criseyde", "Chaucer"])
(cb/make-instance book ["019280619X", "Paradise Lost", "Milton, John"])

(println "this returns maps")
(pprint (cb/query (starts-with :isbn "039")))

(println "this returns struct-map values")
(pprint (cb/query (= :author "Chaucer") :struct book))

(println "this updates the :author slot")
(cb/query (= :author "Chaucer")
          :callback #(cb/passoc! % :author "Chaucer, Geoffrey"))

(println "this verifies that the update worked")
(pprint (cb/query (starts-with :author "Chaucer")))

(cb/close-cupboard!)

This example is available in examples/examples/cupboard/simple.clj. examples/examples/cupboard/gutenberg.clj uses a few more of Cupboard's features.

• Clojure 1.4.0
• Leiningen

Just add [cupboard "1.0beta1"] to your project.clj. Alternatively, add the following to your pom.xml file:

<dependency>
  <groupId>cupboard</groupId>
  <artifactId>cupboard</artifactId>
  <version>1.0beta1</version>
</dependency>

Cupboard's documentation is still a work in progress. Please refer to the doc directory in the source distribution.

Cupboard is distributed under the MIT license, and so has few restrictions itself. Its Berkeley DB dependency, however, is licensed by Oracle — see Oracle's Berkeley DB Licensing Information page for details.