Path: | README.md |
Last Update: | Tue Aug 17 18:02:47 -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)