173 lines
6 KiB
Markdown
173 lines
6 KiB
Markdown
# CouchRest: CouchDB, close to the metal
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CouchRest is based on [CouchDB's couch.js test
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library](http://svn.apache.org/repos/asf/couchdb/trunk/share/www/script/couch.js),
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which I find to be concise, clear, and well designed. CouchRest lightly wraps
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CouchDB's HTTP API, managing JSON serialization, and remembering the URI-paths
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to CouchDB's API endpoints so you don't have to.
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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.
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Note: CouchRest only support CouchDB 0.9.0 or newer.
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## Easy Install
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$ sudo gem install couchrest
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Alternatively, you can install from Github:
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$ gem sources -a http://gems.github.com (you only have to do this once)
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$ sudo gem install couchrest-couchrest
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### Relax, it's RESTful
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CouchRest rests on top of a HTTP abstraction layer using by default Heroku’s excellent REST Client Ruby HTTP wrapper.
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Other adapters can be added to support more http libraries.
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### Running the Specs
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The most complete documentation is the spec/ directory. To validate your
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CouchRest install, from the project root directory run `rake`, or `autotest`
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(requires RSpec and optionally ZenTest for autotest support).
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## Examples (CouchRest Core)
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Quick Start:
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# with !, it creates the database if it doesn't already exist
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@db = CouchRest.database!("http://127.0.0.1:5984/couchrest-test")
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response = @db.save_doc({:key => 'value', 'another key' => 'another value'})
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doc = @db.get(response['id'])
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puts doc.inspect
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Bulk Save:
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@db.bulk_save([
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{"wild" => "and random"},
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{"mild" => "yet local"},
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{"another" => ["set","of","keys"]}
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])
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# returns ids and revs of the current docs
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puts @db.documents.inspect
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Creating and Querying Views:
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@db.save_doc({
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"_id" => "_design/first",
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:views => {
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:test => {
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:map => "function(doc){for(var w in doc){ if(!w.match(/^_/))emit(w,doc[w])}}"
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}
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}
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})
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puts @db.view('first/test')['rows'].inspect
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## CouchRest::ExtendedDocument
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CouchRest::ExtendedDocument is a DSL/ORM for CouchDB. Basically, ExtendedDocument seats on top of CouchRest Core to add the concept of Model.
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ExtendedDocument offers a lot of the usual ORM tools such as optional yet defined schema, validation, callbacks, pagination, casting and much more.
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### Model example
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Check spec/couchrest/more and spec/fixtures/more for more examples
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class Article < CouchRest::ExtendedDocument
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use_database DB
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unique_id :slug
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view_by :date, :descending => true
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view_by :user_id, :date
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view_by :tags,
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:map =>
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"function(doc) {
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if (doc['couchrest-type'] == 'Article' && doc.tags) {
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doc.tags.forEach(function(tag){
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emit(tag, 1);
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});
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}
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}",
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:reduce =>
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"function(keys, values, rereduce) {
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return sum(values);
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}"
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property :date
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property :slug, :read_only => true
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property :title
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property :tags, :cast_as => ['String']
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timestamps!
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save_callback :before, :generate_slug_from_title
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def generate_slug_from_title
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self['slug'] = title.downcase.gsub(/[^a-z0-9]/,'-').squeeze('-').gsub(/^\-|\-$/,'') if new_document?
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end
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end
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### Callbacks
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`CouchRest::ExtendedDocuments` instances have 2 callbacks already defined for you:
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`create_callback`, `save_callback`, `update_callback` and `destroy_callback`
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In your document inherits from `CouchRest::ExtendedDocument`, define your callback as follows:
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save_callback :before, :generate_slug_from_name
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CouchRest uses a mixin you can find in lib/mixins/callbacks which is extracted from Rails 3, here are some simple usage examples:
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save_callback :before, :before_method
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save_callback :after, :after_method, :if => :condition
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save_callback :around {|r| stuff; yield; stuff }
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Check the mixin or the ExtendedDocument class to see how to implement your own callbacks.
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### Properties
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property :last_name, :alias => :family_name
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property :read_only_value, :read_only => true
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property :name, :length => 4...20
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property :price, :type => Integer
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### Casting
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Often, you will want to store multiple objects within a document, to be able to retrieve your objects when you load the document,
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you can define some casting rules.
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property :casted_attribute, :cast_as => 'WithCastedModelMixin'
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property :keywords, :cast_as => ["String"]
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property :occurs_at, :cast_as => 'Time'
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property :end_date, :cast_as => 'Date'
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If you want to cast an array of instances from a specific Class, use the trick shown above ["ClassName"]
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### Pagination
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Pagination is available in any ExtendedDocument classes. Here are some usage examples:
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basic usage:
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Article.all.paginate(:page => 1, :per_page => 5)
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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.
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Slightly more advance usage:
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Article.by_name(:startkey => 'a', :endkey => {}).paginate(:page => 1, :per_page => 5)
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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`
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Basically, you can paginate through the articles starting by the letter a, 5 articles at a time.
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Low level usage:
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Article.paginate(:design_doc => 'Article', :view_name => 'by_date',
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:per_page => 3, :page => 2, :descending => true, :key => Date.today, :include_docs => true)
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## Ruby on Rails
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CouchRest is compatible with rails and can even be used a Rails plugin.
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However, you might be interested in the CouchRest companion rails project:
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[http://github.com/hpoydar/couchrest-rails](http://github.com/hpoydar/couchrest-rails) |