Couchbase Ruby Client

This is the official client library for use with Couchbase Server.


This gem depends on a couple of external libraries to work with JSON and HTTP. For JSON it uses yajl-ruby and yaji which are built atop of yajl. For HTTP iteraction it uses curb, the curl bindings for ruby. To install it use your package manager. On debian you can install it, use aptitude:

$ sudo aptitude install libcurl3-dev

After that you can install the gem via rubygems:

$ gem install couchbase


First of all you need to load library:

require 'couchbase'

To establish connection with couchbase you need to specify at least pool URI. Also you can choose custom bucket name and memcached SASL authentication and Couchbase REST API.

c ="http://localhost:8091/pools/default")
c ="http://localhost:8091/pools/default", :bucket_name => 'blog')
c ="http://localhost:8091/pools/default",
                  :bucket_name => 'blog', :bucket_password => 'secret')

This gem supports memcached API accessible for memcached client with a bit syntax sugar:

c.set('password', 'secret')
c.get('password')             #=> "secret"
c['password'] = 'secret'
c['password']                 #=> "secret"
c['counter'] = 1              #=> 1
c['counter'] += 1             #=> 2
c['counter']                  #=> 2
c.increment('counter', 10)

But if you store structured data, they will be treated as documents and you can handle them in map/reduce function from CouchDB views. For example, store a couple of posts using memcached API:

c['biking'] = {:title => 'Biking',
               :body => 'I went to the the pet store earlier and brought home a little kitty...',
               :date => '2009/01/30 18:04:11'}
c['bought-a-cat'] = {:title => 'Biking',
                     :body => 'My biggest hobby is mountainbiking. The other day...',
                     :date => '2009/01/30 18:04:11'}
c['hello-world'] = {:title => 'Hello World',
                    :body => 'Well hello and welcome to my new blog...',
                    :date => '2009/01/15 15:52:20'}
c.all_docs.count    #=> 3

Now let's create design doc with sample view and save it in file 'blog.json':

  "_id": "_design/blog",
  "language": "javascript",
  "views": {
    "recent_posts": {
      "map": "function(doc){if( && doc.title){emit(, doc.title);}}"

This design document could be loaded into the database like this (also you can pass the ruby Hash or String with JSON encoded document):


To execute view you need to fetch it from design document _design/blog:

blog = c.design_docs['blog']
blog.views                    #=> ["recent_posts"]
blog.recent_posts             #=> [#<Couchbase::Document:14244860 {"id"=>"hello-world", "key"=>"2009/01/15 15:52:20", "value"=>"Hello World"}>,...]

Gem uses streaming parser to access view results so you can iterate them easily and if your code won't keep links to the documents GC might free them as soon as it decide they are unreachable, because parser doesn't store global JSON tree.

posts = blog.recent_posts.each do |doc|
  # do something
  # with doc object

You can also use Enumerator to iterate view results

require 'date'
posts_by_date ={|h,k| h[k] = []}
enum = c.all_docs.each  # request hasn't issued yet
enum.inject(posts_by_date) do |acc, doc|
  acc[date] = Date.strptime(doc['date'], '%Y/%m/%d')

The Couchbase server could generate errors during view execution with 200 OK and partial results. By default the library raises exception as soon as errors detected in the result stream, but you can define the callback on_error to intercept these errors and do something more useful.

view = blog.recent_posts
logger =

view.on_error do |from, reason|
  logger.warn("#{view.inspect} received the error '#{reason}' from #{from}")

posts = view.each do |doc|
  # do something
  # with doc object

Note that errors object in view results usually goes after the rows, so you will likely receive a number of view results successfully before the error is detected.