couchrest_model/lib/couchrest/mixins/views.rb

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module CouchRest
module Mixins
module Views
def self.included(base)
base.extend(ClassMethods)
base.send(:class_inheritable_accessor, :design_doc)
base.send(:class_inheritable_accessor, :design_doc_slug_cache)
base.send(:class_inheritable_accessor, :design_doc_fresh)
end
module ClassMethods
# Define a CouchDB view. The name of the view will be the concatenation
# of <tt>by</tt> and the keys joined by <tt>_and_</tt>
#
# ==== Example views:
#
# class Post
# # view with default options
# # query with Post.by_date
# view_by :date, :descending => true
#
# # view with compound sort-keys
# # query with Post.by_user_id_and_date
# view_by :user_id, :date
#
# # view with custom map/reduce functions
# # query with Post.by_tags :reduce => true
# view_by :tags,
# :map =>
# "function(doc) {
# if (doc['couchrest-type'] == 'Post' && doc.tags) {
# doc.tags.forEach(function(tag){
# emit(doc.tag, 1);
# });
# }
# }",
# :reduce =>
# "function(keys, values, rereduce) {
# return sum(values);
# }"
# end
#
# <tt>view_by :date</tt> will create a view defined by this Javascript
# function:
#
# function(doc) {
# if (doc['couchrest-type'] == 'Post' && doc.date) {
# emit(doc.date, null);
# }
# }
#
# It can be queried by calling <tt>Post.by_date</tt> which accepts all
# valid options for CouchRest::Database#view. In addition, calling with
# the <tt>:raw => true</tt> option will return the view rows
# themselves. By default <tt>Post.by_date</tt> will return the
# documents included in the generated view.
#
# CouchRest::Database#view options can be applied at view definition
# time as defaults, and they will be curried and used at view query
# time. Or they can be overridden at query time.
#
# Custom views can be queried with <tt>:reduce => true</tt> to return
# reduce results. The default for custom views is to query with
# <tt>:reduce => false</tt>.
#
# Views are generated (on a per-model basis) lazily on first-access.
# This means that if you are deploying changes to a view, the views for
# that model won't be available until generation is complete. This can
# take some time with large databases. Strategies are in the works.
#
# To understand the capabilities of this view system more compeletly,
# it is recommended that you read the RSpec file at
# <tt>spec/core/model_spec.rb</tt>.
def view_by(*keys)
self.design_doc ||= Design.new(default_design_doc)
opts = keys.pop if keys.last.is_a?(Hash)
opts ||= {}
ducktype = opts.delete(:ducktype)
unless ducktype || opts[:map]
opts[:guards] ||= []
opts[:guards].push "(doc['couchrest-type'] == '#{self.to_s}')"
end
keys.push opts
self.design_doc.view_by(*keys)
self.design_doc_fresh = false
end
# returns stored defaults if the there is a view named this in the design doc
def has_view?(view)
view = view.to_s
design_doc && design_doc['views'] && design_doc['views'][view]
end
# Dispatches to any named view.
def view(name, query={}, &block)
unless design_doc_fresh
refresh_design_doc
end
query[:raw] = true if query[:reduce]
raw = query.delete(:raw)
fetch_view_with_docs(name, query, raw, &block)
end
def all_design_doc_versions
database.documents :startkey => "_design/#{self.to_s}-",
:endkey => "_design/#{self.to_s}-\u9999"
end
# Deletes any non-current design docs that were created by this class.
# Running this when you're deployed version of your application is steadily
# and consistently using the latest code, is the way to clear out old design
# docs. Running it to early could mean that live code has to regenerate
# potentially large indexes.
def cleanup_design_docs!
ddocs = all_design_doc_versions
ddocs["rows"].each do |row|
if (row['id'] != design_doc_id)
database.delete_doc({
"_id" => row['id'],
"_rev" => row['value']['rev']
})
end
end
end
private
def fetch_view_with_docs(name, opts, raw=false, &block)
if raw || (opts.has_key?(:include_docs) && opts[:include_docs] == false)
fetch_view(name, opts, &block)
else
begin
view = fetch_view name, opts.merge({:include_docs => true}), &block
view['rows'].collect{|r|new(r['doc'])} if view['rows']
rescue
# fallback for old versions of couchdb that don't
# have include_docs support
view = fetch_view(name, opts, &block)
view['rows'].collect{|r|new(database.get(r['id']))} if view['rows']
end
end
end
def fetch_view view_name, opts, &block
retryable = true
begin
design_doc.view(view_name, opts, &block)
# the design doc could have been deleted by a rouge process
rescue RestClient::ResourceNotFound => e
if retryable
refresh_design_doc
retryable = false
retry
else
raise e
end
end
end
end # module ClassMethods
end
end
end