Class: Ramaze::Pager

Inherits:
Object show all
Includes:
Helper::Link, Traited
Defined in:
lib/ramaze/helper/pager.rb

Overview

Displays a collection of entitities in multiple pages.

Design

This pager is carefully designed for scaleability. It stores only the items for one page. The key parameter is needed, multiple pagers can coexist in a single page. The pager leverages the SQL LIMIT option to optimize database interaction.

Example

class MyController
  def index
    objs = (0..200).to_a
    @entries, @pager = paginate(objs, :limit => 20)
  end
end

<html>
  <head><title>Pager</title></head>
  <body>
    <?r if pager.navigation? ?>
      <div class="pager">#{@pager.navigation}</div>
    <?r end ?>
    <ul>
    <?r @entries.each do |entry| ?>
      <li>#{entry}</li>
    <?r end ?>
    </ul>
  </body>
</html>

Styling

The following classes can be used for styling with CSS (provided you put the pager in a element with class ‘pager’ like shown above):

.pager {}
.pager .first {}
.pager .previous {}
.pager .next {}
.pager .last {}
.pager ul {}
.pager li {}
.pager li.active {}

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Helper::Link

#breadcrumbs, #route_location

Constructor Details

#initialize(request, limit, total_count, key = trait[:key]) ⇒ Pager

Create a new Pager object.

request

Ramaze::Request object providing access to GET parameters

limit

how many elements go to one page

total_count

total element count

key

key used for getting the current page from GET paramaters

Note: You never have to create this class yourself, use the ‘paginate()` convenience method from the Helper::Pager.



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# File 'lib/ramaze/helper/pager.rb', line 122

def initialize(request, limit, total_count, key = trait[:key])
  raise 'limit should be > 0' unless limit > 0

  @request, @key = request, key
  @page = (request.params[key] || 1).to_i
  @limit = limit
  set_count(total_count)
  @start_idx = (@page - 1) * limit
end

Instance Attribute Details

#limit ⇒ Object (readonly)

To be used with Og queries.



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# File 'lib/ramaze/helper/pager.rb', line 102

def limit
  @limit
end

#page ⇒ Object (readonly)

The current page.



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# File 'lib/ramaze/helper/pager.rb', line 98

def page
  @page
end

#page_count ⇒ Object (readonly)

The total number of pages.



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# File 'lib/ramaze/helper/pager.rb', line 106

def page_count
  @page_count
end

#total_count ⇒ Object (readonly)

Total count of items.



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# File 'lib/ramaze/helper/pager.rb', line 110

def total_count
  @total_count
end

Instance Method Details

#each(&block) ⇒ Object

Returns each element for the current page



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# File 'lib/ramaze/helper/pager.rb', line 170

def each(&block)
  @page_items.each(&block)
end

#each_with_index(&block) ⇒ Object

Iterator Returns 1-based index.



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# File 'lib/ramaze/helper/pager.rb', line 177

def each_with_index(&block)
  @page_items.each_with_index(&block)
end

#empty? ⇒ Boolean

Is the pager empty, ie has one page only?

Returns:

  • (Boolean) 


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# File 'lib/ramaze/helper/pager.rb', line 183

def empty?
  @page_count < 2
end

#first_page ⇒ Object

Return the first page index.



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# File 'lib/ramaze/helper/pager.rb', line 134

def first_page
  1
end

#first_page? ⇒ Boolean

Is the first page displayed?

Returns:

  • (Boolean) 


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# File 'lib/ramaze/helper/pager.rb', line 140

def first_page?
  @page == 1
end

#last_page ⇒ Object

Return the last page index.



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# File 'lib/ramaze/helper/pager.rb', line 146

def last_page
  return @page_count
end

#last_page? ⇒ Boolean

Is the last page displayed?

Returns:

  • (Boolean) 


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# File 'lib/ramaze/helper/pager.rb', line 152

def last_page?
  @page == @page_count
end

#navigation ⇒ Object

Override this method in your application if needed. – TODO: better markup. ++



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# File 'lib/ramaze/helper/pager.rb', line 205

def navigation
  nav = ""

  unless first_page?
    nav << %{
      <div class="first"><a href="#{link_first_page}">First</a></div>
      <div class="previous"><a href="#{link_prev_page}">Previous</a></div>
    }
  end

  unless last_page?
    nav << %{
      <div class="last"><a href="#{link_last_page}">Last</a></div>
      <div class="next"><a href="#{link_next_page}">Next</a></div>
    }
  end

  nav << %{<ul>}

  for i in nav_range()
    if i == @page
      nav << %{<li class="active">#{i}</li>}
    else
      nav << %{<li><a href="#{target_uri(i)}">#{i}</a></li>}
    end
  end

  nav << %{</ul>}

  return nav
end

#navigation? ⇒ Boolean

Returns true if a navigation is necessary (meaning there is more than one page)

Returns:

  • (Boolean) 


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# File 'lib/ramaze/helper/pager.rb', line 190

def navigation?
  !empty?
end

#next_page ⇒ Object

Return the index of the next page.



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# File 'lib/ramaze/helper/pager.rb', line 164

def next_page
  [@page + 1, @page_count].min
end

#offset ⇒ Object

Returns the index of the first element to go into the current page



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# File 'lib/ramaze/helper/pager.rb', line 249

def offset
  @start_idx
end

#prev_page ⇒ Object

Return the index of the previous page.



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# File 'lib/ramaze/helper/pager.rb', line 158

def prev_page
  [@page - 1, 1].max
end

#size ⇒ Object

Returns the amount of all elements in all pages.



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# File 'lib/ramaze/helper/pager.rb', line 196

def size
  @total_count
end