couchrest_model/lib/couchrest/mixins/collection.rb

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module CouchRest
module Mixins
module Collection
def self.included(base)
base.extend(ClassMethods)
end
module ClassMethods
# Creates a new class method, find_all_<collection_name>, that will
# execute the view specified with the design_doc and view_name
# parameters, along with the specified view_options. This method will
# return the results of the view as an Array of objects which are
# instances of the class.
#
# This method is handy for objects that do not use the view_by method
# to declare their views.
def provides_collection(collection_name, design_doc, view_name, view_options)
class_eval <<-END, __FILE__, __LINE__ + 1
def self.find_all_#{collection_name}(options = {})
view_options = #{view_options.inspect} || {}
CollectionProxy.new(@database, "#{design_doc}", "#{view_name}", view_options.merge(options), Kernel.const_get('#{self}'))
end
END
end
# Fetch a group of objects from CouchDB. Options can include:
# :page - Specifies the page to load (starting at 1)
# :per_page - Specifies the number of objects to load per page
#
# Defaults are used if these options are not specified.
def paginate(options)
proxy = create_collection_proxy(options)
proxy.paginate(options)
end
# Iterate over the objects in a collection, fetching them from CouchDB
# in groups. Options can include:
# :page - Specifies the page to load
# :per_page - Specifies the number of objects to load per page
#
# Defaults are used if these options are not specified.
def paginated_each(options, &block)
proxy = create_collection_proxy(options)
proxy.paginated_each(options, &block)
end
# Create a CollectionProxy for the specified view and options.
# CollectionProxy behaves just like an Array, but offers support for
# pagination.
def collection_proxy_for(design_doc, view_name, view_options = {})
options = view_options.merge(:design_doc => design_doc, :view_name => view_name)
create_collection_proxy(options)
end
private
def create_collection_proxy(options)
design_doc, view_name, view_options = parse_view_options(options)
CollectionProxy.new(@database, design_doc, view_name, view_options, self)
end
def parse_view_options(options)
design_doc = options.delete(:design_doc)
raise ArgumentError, 'design_doc is required' if design_doc.nil?
view_name = options.delete(:view_name)
raise ArgumentError, 'view_name is required' if view_name.nil?
default_view_options = (design_doc.class == Design &&
design_doc['views'][view_name.to_s] &&
design_doc['views'][view_name.to_s]["couchrest-defaults"]) || {}
view_options = default_view_options.merge(options)
[design_doc, view_name, view_options]
end
end
class CollectionProxy
alias_method :proxy_respond_to?, :respond_to?
instance_methods.each { |m| undef_method m unless m =~ /(^__|^nil\?$|^send$|proxy_|^object_id$)/ }
DEFAULT_PAGE = 1
DEFAULT_PER_PAGE = 30
# Create a new CollectionProxy to represent the specified view. If a
# container class is specified, the proxy will create an object of the
# given type for each row that comes back from the view. If no
# container class is specified, the raw results are returned.
#
# The CollectionProxy provides support for paginating over a collection
# via the paginate, and paginated_each methods.
def initialize(database, design_doc, view_name, view_options = {}, container_class = nil)
raise ArgumentError, "database is a required parameter" if database.nil?
@database = database
@container_class = container_class
strip_pagination_options(view_options)
@view_options = view_options
if design_doc.class == Design
@view_name = "#{design_doc.name}/#{view_name}"
else
@view_name = "#{design_doc}/#{view_name}"
end
end
# See Collection.paginate
def paginate(options = {})
page, per_page = parse_options(options)
results = @database.view(@view_name, pagination_options(page, per_page))
remember_where_we_left_off(results, page)
convert_to_container_array(results)
end
# See Collection.paginated_each
def paginated_each(options = {}, &block)
page, per_page = parse_options(options)
begin
collection = paginate({:page => page, :per_page => per_page})
collection.each(&block)
page += 1
end until collection.size < per_page
end
def respond_to?(*args)
proxy_respond_to?(*args) || (load_target && @target.respond_to?(*args))
end
# Explicitly proxy === because the instance method removal above
# doesn't catch it.
def ===(other)
load_target
other === @target
end
private
def method_missing(method, *args)
if load_target
if block_given?
@target.send(method, *args) { |*block_args| yield(*block_args) }
else
@target.send(method, *args)
end
end
end
def load_target
unless loaded?
results = @database.view(@view_name, @view_options)
@target = convert_to_container_array(results)
end
@loaded = true
@target
end
def loaded?
@loaded
end
def reload
reset
load_target
self unless @target.nil?
end
def reset
@loaded = false
@target = nil
end
def inspect
load_target
@target.inspect
end
def convert_to_container_array(results)
if @container_class.nil?
results
else
results['rows'].collect { |row| @container_class.new(row['doc']) } unless results['rows'].nil?
end
end
def pagination_options(page, per_page)
view_options = @view_options.clone
if @last_key && @last_docid && @last_page == page - 1
view_options.delete(:key)
options = { :startkey => @last_key, :startkey_docid => @last_docid, :limit => per_page, :skip => 1 }
else
options = { :limit => per_page, :skip => per_page * (page - 1) }
end
view_options.merge(options)
end
def parse_options(options)
page = options.delete(:page) || DEFAULT_PAGE
per_page = options.delete(:per_page) || DEFAULT_PER_PAGE
[page.to_i, per_page.to_i]
end
def strip_pagination_options(options)
parse_options(options)
end
def remember_where_we_left_off(results, page)
last_row = results['rows'].last
if last_row
@last_key = last_row['key']
@last_docid = last_row['id']
end
@last_page = page
end
end
end
end
end