module ActionController # === Action Pack pagination for Active Record collections # # The Pagination module aids in the process of paging large collections of # Active Record objects. It offers macro-style automatic fetching of your # model for multiple views, or explicit fetching for single actions. And if # the magic isn't flexible enough for your needs, you can create your own # paginators with a minimal amount of code. # # The Pagination module can handle as much or as little as you wish. In the # controller, have it automatically query your model for pagination; or, # if you prefer, create Paginator objects yourself. # # Pagination is included automatically for all controllers. # # For help rendering pagination links, see # ActionView::Helpers::PaginationHelper. # # ==== Automatic pagination for every action in a controller # # class PersonController < ApplicationController # model :person # # paginate :people, :order_by => 'last_name, first_name', # :per_page => 20 # # # ... # end # # Each action in this controller now has access to a @people # instance variable, which is an ordered collection of model objects for the # current page (at most 20, sorted by last name and first name), and a # @person_pages Paginator instance. The current page is determined # by the @params['page'] variable. # # ==== Pagination for a single action # # def list # @person_pages, @people = # paginate :people, :order_by => 'last_name, first_name' # end # # Like the previous example, but explicitly creates @person_pages # and @people for a single action, and uses the default of 10 items # per page. # # ==== Custom/"classic" pagination # # def list # @person_pages = Paginator.new self, Person.count, 10, @params['page'] # @people = Person.find_all nil, 'last_name, first_name', # @person_pages.current.to_sql # end # # Explicitly creates the paginator from the previous example and uses # Paginator#to_sql to retrieve @people from the model. # module Pagination unless const_defined?(:OPTIONS) # A hash holding options for controllers using macro-style pagination OPTIONS = Hash.new # The default options for pagination DEFAULT_OPTIONS = { :class_name => nil, :per_page => 10, :conditions => nil, :order_by => nil, :join => nil, :parameter => 'page' } end def self.included(base) #:nodoc: super base.extend(ClassMethods) end def self.validate_options!(collection_id, options, in_action) #:nodoc: options.merge!(DEFAULT_OPTIONS) {|key, old, new| old} valid_options = DEFAULT_OPTIONS.keys valid_options << :actions unless in_action unknown_option_keys = options.keys - valid_options raise ActionController::ActionControllerError, "Unknown options: #{unknown_option_keys.join(', ')}" unless unknown_option_keys.empty? options[:singular_name] = Inflector.singularize(collection_id.to_s) options[:class_name] ||= Inflector.camelize(options[:singular_name]) end # Returns a paginator and a collection of Active Record model instances # for the paginator's current page. This is designed to be used in a # single action; to automatically paginate multiple actions, consider # ClassMethods#paginate. # # +options+ are: # :class_name:: the class name to use, if it can't be inferred by # singularizing the collection name # :per_page:: the maximum number of items to include in a # single page. Defaults to 10 # :conditions:: optional conditions passed to Model.find_all and # Model.count # :order_by:: optional order parameter passed to Model.find_all # :join:: optional join parameter passed to Model.find_all # and Model.count def paginate(collection_id, options={}) Pagination.validate_options!(collection_id, options, true) paginator_and_collection_for(collection_id, options) end # These methods become class methods on any controller module ClassMethods # Creates a +before_filter+ which automatically paginates an Active # Record model for all actions in a controller (or certain actions if # specified with the :actions option). # # +options+ are the same as PaginationHelper#paginate, with the addition # of: # :actions:: an array of actions for which the pagination is # active. Defaults to +nil+ (i.e., every action) def paginate(collection_id, options={}) Pagination.validate_options!(collection_id, options, false) module_eval do before_filter :create_paginators_and_retrieve_collections OPTIONS[self] ||= Hash.new OPTIONS[self][collection_id] = options end end end def create_paginators_and_retrieve_collections #:nodoc: Pagination::OPTIONS[self.class].each do |collection_id, options| next unless options[:actions].include? action_name if options[:actions] paginator, collection = paginator_and_collection_for(collection_id, options) paginator_name = "@#{options[:singular_name]}_pages" self.instance_variable_set(paginator_name, paginator) collection_name = "@#{collection_id.to_s}" self.instance_variable_set(collection_name, collection) end end # Returns the total number of items in the collection to be paginated for # the +model+ and given +conditions+. Override this method to implement a # custom counter. def count_collection_for_pagination(model, conditions, joins) model.count(conditions,joins) end # Returns a collection of items for the given +model+ and +conditions+, # ordered by +order_by+, for the current page in the given +paginator+. # Override this method to implement a custom finder. def find_collection_for_pagination(model, conditions, order_by, join, paginator) model.find_all(conditions, order_by, paginator.current.to_sql, join) end protected :create_paginators_and_retrieve_collections, :count_collection_for_pagination, :find_collection_for_pagination def paginator_and_collection_for(collection_id, options) #:nodoc: klass = options[:class_name].constantize page = @params[options[:parameter]] count = count_collection_for_pagination(klass, options[:conditions], options[:join]) paginator = Paginator.new(self, count, options[:per_page], page) collection = find_collection_for_pagination(klass, options[:conditions], options[:order_by], options[:join], paginator) return paginator, collection end private :paginator_and_collection_for # A class representing a paginator for an Active Record collection. class Paginator include Enumerable # Creates a new Paginator on the given +controller+ for a set of items # of size +item_count+ and having +items_per_page+ items per page. # Raises ArgumentError if items_per_page is out of bounds (i.e., less # than or equal to zero). The page CGI parameter for links defaults to # "page" and can be overridden with +page_parameter+. def initialize(controller, item_count, items_per_page, current_page=1) raise ArgumentError, 'must have at least one item per page' if items_per_page <= 0 @controller = controller @item_count = item_count || 0 @items_per_page = items_per_page self.current_page = current_page end attr_reader :controller, :item_count, :items_per_page # Sets the current page number of this paginator. If +page+ is a Page # object, its +number+ attribute is used as the value; if the page does # not belong to this Paginator, an ArgumentError is raised. def current_page=(page) if page.is_a? Page raise ArgumentError, 'Page/Paginator mismatch' unless page.paginator == self end page = page.to_i @current_page = has_page_number?(page) ? page : 1 end # Returns a Page object representing this paginator's current page. def current_page self[@current_page] end alias current :current_page # Returns a new Page representing the first page in this paginator. def first_page self[1] end alias first :first_page # Returns a new Page representing the last page in this paginator. def last_page self[page_count] end alias last :last_page # Returns the number of pages in this paginator. def page_count return 1 if @item_count.zero? (@item_count / @items_per_page.to_f).ceil end alias length :page_count # Returns true if this paginator contains the page of index +number+. def has_page_number?(number) return false unless number.is_a? Fixnum number >= 1 and number <= page_count end # Returns a new Page representing the page with the given index # +number+. def [](number) Page.new(self, number) end # Successively yields all the paginator's pages to the given block. def each(&block) page_count.times do |n| yield self[n+1] end end # A class representing a single page in a paginator. class Page include Comparable # Creates a new Page for the given +paginator+ with the index # +number+. If +number+ is not in the range of valid page numbers or # is not a number at all, it defaults to 1. def initialize(paginator, number) @paginator = paginator @number = number.to_i @number = 1 unless @paginator.has_page_number? @number end attr_reader :paginator, :number alias to_i :number # Compares two Page objects and returns true when they represent the # same page (i.e., their paginators are the same and they have the # same page number). def ==(page) return false if page.nil? @paginator == page.paginator and @number == page.number end # Compares two Page objects and returns -1 if the left-hand page comes # before the right-hand page, 0 if the pages are equal, and 1 if the # left-hand page comes after the right-hand page. Raises ArgumentError # if the pages do not belong to the same Paginator object. def <=>(page) raise ArgumentError unless @paginator == page.paginator @number <=> page.number end # Returns the item offset for the first item in this page. def offset @paginator.items_per_page * (@number - 1) end # Returns the number of the first item displayed. def first_item offset + 1 end # Returns the number of the last item displayed. def last_item [@paginator.items_per_page * @number, @paginator.item_count].min end # Returns true if this page is the first page in the paginator. def first? self == @paginator.first end # Returns true if this page is the last page in the paginator. def last? self == @paginator.last end # Returns a new Page object representing the page just before this # page, or nil if this is the first page. def previous if first? then nil else Page.new(@paginator, @number - 1) end end # Returns a new Page object representing the page just after this # page, or nil if this is the last page. def next if last? then nil else Page.new(@paginator, @number + 1) end end # Returns a new Window object for this page with the specified # +padding+. def window(padding=2) Window.new(self, padding) end # Returns the limit/offset array for this page. def to_sql [@paginator.items_per_page, offset] end def to_param #:nodoc: @number.to_s end end # A class for representing ranges around a given page. class Window # Creates a new Window object for the given +page+ with the specified # +padding+. def initialize(page, padding=2) @paginator = page.paginator @page = page self.padding = padding end attr_reader :paginator, :page # Sets the window's padding (the number of pages on either side of the # window page). def padding=(padding) @padding = padding < 0 ? 0 : padding # Find the beginning and end pages of the window @first = @paginator.has_page_number?(@page.number - @padding) ? @paginator[@page.number - @padding] : @paginator.first @last = @paginator.has_page_number?(@page.number + @padding) ? @paginator[@page.number + @padding] : @paginator.last end attr_reader :padding, :first, :last # Returns an array of Page objects in the current window. def pages (@first.number..@last.number).to_a.map {|n| @paginator[n]} end alias to_a :pages end end end end