CouchRest: CouchDB, close to the metal

CouchRest is based on CouchDB's couch.js test library, which I find to be concise, clear, and well designed. CouchRest lightly wraps CouchDB's HTTP API, managing JSON serialization, and remembering the URI-paths to CouchDB's API endpoints so you don't have to.

CouchRest is designed to make a simple base for application and framework-specific object oriented APIs. CouchRest is Object-Mapper agnostic, the parsed JSON it returns from CouchDB shows up as subclasses of Ruby's Hash. Naked JSON, just as it was mean to be.

Note: CouchRest only support CouchDB 0.9.0 or newer.

Easy Install

Easy Install is moving to RubyForge, heads up for the gem.

Relax, it's RESTful

The core of Couchrest is Heroku’s excellent REST Client Ruby HTTP wrapper. REST Client takes all the nastyness of Net::HTTP and gives is a pretty face, while still giving you more control than Open-URI. I recommend it anytime you’re interfacing with a well-defined web service.

Running the Specs

The most complete documentation is the spec/ directory. To validate your CouchRest install, from the project root directory run rake, or autotest (requires RSpec and optionally ZenTest for autotest support).

Examples

Quick Start:

# with !, it creates the database if it doesn't already exist
@db = CouchRest.database!("http://127.0.0.1:5984/couchrest-test")
response = @db.save_doc({:key => 'value', 'another key' => 'another value'})
doc = @db.get(response['id'])
puts doc.inspect

Bulk Save:

@db.bulk_save([
    {"wild" => "and random"},
    {"mild" => "yet local"},
    {"another" => ["set","of","keys"]}
  ])
# returns ids and revs of the current docs
puts @db.documents.inspect 

Creating and Querying Views:

@db.save_doc({
  "_id" => "_design/first", 
  :views => {
    :test => {
      :map => "function(doc){for(var w in doc){ if(!w.match(/^_/))emit(w,doc[w])}}"
      }
    }
  })
puts @db.view('first/test')['rows'].inspect 

CouchRest::Model

CouchRest::Model has been deprecated and replaced by CouchRest::ExtendedDocument

CouchRest::ExtendedDocument

Callbacks

CouchRest::ExtendedDocuments instances have 2 callbacks already defined for you: create_callback, save_callback, update_callback and destroy_callback

In your document inherits from CouchRest::ExtendedDocument, define your callback as follows:

save_callback :before, :generate_slug_from_name

CouchRest uses a mixin you can find in lib/mixins/callbacks which is extracted from Rails 3, here are some simple usage examples:

save_callback :before, :before_method
save_callback :after,  :after_method, :if => :condition
save_callback :around {|r| stuff; yield; stuff }

Check the mixin or the ExtendedDocument class to see how to implement your own callbacks.

Casting

Often, you will want to store multiple objects within a document, to be able to retrieve your objects when you load the document, you can define some casting rules.

property :casted_attribute, :cast_as => 'WithCastedModelMixin'
property :keywords,         :cast_as => ["String"]

If you want to cast an array of instances from a specific Class, use the trick shown above ["ClassName"]

Pagination

Pagination is available in any ExtendedDocument classes. Here are some usage examples:

basic usage:

Article.all.paginate(:page => 1, :per_page => 5)

note: the above query will look like: GET /db/_design/Article/_view/all?include_docs=true&skip=0&limit=5&reduce=false and only fetch 5 documents.

Slightly more advance usage:

Article.by_name(:startkey => 'a', :endkey => {}).paginate(:page => 1, :per_page => 5)

note: the above query will look like: GET /db/_design/Article/_view/by_name?startkey=%22a%22&limit=5&skip=0&endkey=%7B%7D&include_docs=true
Basically, you can paginate through the articles starting by the letter a, 5 articles at a time.

Low level usage:

Article.paginate(:design_doc => 'Article', :view_name => 'by_date',
  :per_page => 3, :page => 2, :descending => true, :key => Date.today, :include_docs => true)