| Path: | README.md | 
| Last Update: | Thu Aug 19 05:59:16 -0600 2010 | 
# CouchRest: CouchDB, close to the metal
CouchRest is based on [CouchDB‘s couch.js test library](svn.apache.org/repos/asf/couchdb/trunk/share/www/script/couch.js), 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
    $ sudo gem install couchrest
Alternatively, you can install from Github:
    $ gem sources -a http://gems.github.com (you only have to do this once)
    $ sudo gem install couchrest-couchrest
### Relax, it‘s RESTful
CouchRest rests on top of a HTTP abstraction layer using by default Heroku’s excellent REST Client Ruby HTTP wrapper. Other adapters can be added to support more http libraries.
### 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 (CouchRest Core)
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::ExtendedDocument
CouchRest::ExtendedDocument is a DSL/ORM for CouchDB. Basically, ExtendedDocument seats on top of CouchRest Core to add the concept of Model. ExtendedDocument offers a lot of the usual ORM tools such as optional yet defined schema, validation, callbacks, pagination, casting and much more.
### Model example
Check spec/couchrest/more and spec/fixtures/more for more examples
    class Article < CouchRest::ExtendedDocument
      use_database DB
      unique_id :slug
      view_by :date, :descending => true
      view_by :user_id, :date
      view_by :tags,
        :map =>
          "function(doc) {
            if (doc['couchrest-type'] == 'Article' && doc.tags) {
              doc.tags.forEach(function(tag){
                emit(tag, 1);
              });
            }
          }",
        :reduce =>
          "function(keys, values, rereduce) {
            return sum(values);
          }"
      property :date
      property :slug, :read_only => true
      property :title
      property :tags, :cast_as => ['String']
      timestamps!
      save_callback :before, :generate_slug_from_title
      def generate_slug_from_title
        self['slug'] = title.downcase.gsub(/[^a-z0-9]/,'-').squeeze('-').gsub(/^\-|\-$/,'') if new_document?
      end
    end
### 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)
## Ruby on Rails
CouchRest is compatible with rails and can even be used a Rails plugin. However, you might be interested in the CouchRest companion rails project: [github.com/hpoydar/couchrest-rails](http://github.com/hpoydar/couchrest-rails)