Class: Tesco::Groceries::Paginated

Inherits:
Object
  • Object
show all
Defined in:
lib/tesco.rb

Overview

A special class that takes care of product pagination automatically. It’ll work like a read-only array for the most part but you can request a specific page with #page and requesting a specific item with #[] will request the required page automatically if it hasn’t already been retrieved and stored within the instance’s cache.

Direct Known Subclasses

Products

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(api, res) ⇒ Paginated

Don’t use this yourself!



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# File 'lib/tesco.rb', line 456

def initialize(api,res) # :nodoc:
  @cached_pages = {}
  @api = api
  # Do the page we've been given (usually the first)
  @cached_pages[res['PageNumber'] || 1] = parse_items(res)
  @pages = res['TotalPageCount'] || 1
  @perpage = res['PageProductCount']
  @length = res['TotalProductCount'] || @perpage
  @params = res[:requestparameters]
end

Instance Attribute Details

#length ⇒ Object (readonly)

Returns the value of attribute length.



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# File 'lib/tesco.rb', line 454

def length
  @length
end

#pages ⇒ Object (readonly)

Returns the value of attribute pages.



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# File 'lib/tesco.rb', line 454

def pages
  @pages
end

Instance Method Details

#[](n) ⇒ Object

Will return the item at the requested index, even if that page hasn’t yet been retreived

Raises:

  • (TypeError) 


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# File 'lib/tesco.rb', line 468

def [](n)
  raise TypeError, "That isn't a valid array reference" if not (n.is_a? Integer and n >= 0)
  raise PaginationError, "That index exceeds the number of items" if n >= @length
  page_num = (n / @perpage).floor + 1
  page(page_num)[n - page_num * @perpage]
end

#each(pages = :all) ⇒ Object

Akin to Array#each, except you must specify which page, or range of pages, of products you wish to iterate over.

Specifying page = 0 or page = :all will iterate over every item on every page

The items on each page will be passed to your block as they’re retrieved, so you’ll get spurts of output.

NB. This method won’t check your enumberable for each item being a valid page until it’s processed all prior pages.



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# File 'lib/tesco.rb', line 494

def each(pages = :all)
  pages = (1..@pages) if (pages == :all or pages == 0)
  pages = [pages] if not pages.is_a? Enumerable
  pages.each do |page|
    raise PaginationError, "#{page.inspect} isn't a valid page reference" if not (page.is_a? Integer and page >= 0 and page <= @pages)
    page(page).each do |item|
      yield item
    end
  end
end

#inspect ⇒ Object 



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# File 'lib/tesco.rb', line 505

def inspect
  output = ""
  previous = 0
  @cached_pages.each_pair do |page,content|
    output << ", … #{(page - previous) * @perpage} more …" if (previous + 1) != page
    output << ", " << content.inspect[1..-2]
    previous = page
  end
  output << ", … #{@length - previous * @perpage} more" if previous != @pages
  "[#{output[2..-1]}]"
end

#page(page) ⇒ Object

Will return all the items on the requested page (indeces will be relative to the page). Specifying page = 0 or page = :all will give an array of all items, retrieving all details first This could take a very, vey long time!

Raises:



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# File 'lib/tesco.rb', line 478

def page(page)
  page = 0 if page == :all
  raise PaginationError, "That isn't a valid page reference" if not (page.is_a? Integer and page >= 0 and page <= @pages)
  if !@cached_pages.keys.include?(page)
    @cached_pages[res['PageNumber'] || 1] = parse_items(@api.api_request(nil,@params.merge({:page => page})))
  end
  @cached_pages[page]
end