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# Helpers to sort tables using clickable column headers.
#
# Author: Stuart Rackham <srackham@methods.co.nz>, March 2005.
# License: This source code is released under the MIT license.
#
# - Consecutive clicks toggle the column's sort order.
# - Sort state is maintained by a session hash entry.
# - Icon image identifies sort column and state.
# - Typically used in conjunction with the Pagination module.
#
# Example code snippets:
#
# Controller:
#
# helper :sort
# include SortHelper
#
# def list
# sort_init 'last_name'
# sort_update
# @items = Contact.find_all nil, sort_clause
# end
#
# Controller (using Pagination module):
#
# helper :sort
# include SortHelper
#
# def list
# sort_init 'last_name'
# sort_update
# @contact_pages, @items = paginate :contacts,
# :order_by => sort_clause,
# :per_page => 10
# end
#
# View (table header in list.rhtml):
#
# <thead>
# <tr>
# <%= sort_header_tag('id', :title => 'Sort by contact ID') %>
# <%= sort_header_tag('last_name', :caption => 'Name') %>
# <%= sort_header_tag('phone') %>
# <%= sort_header_tag('address', :width => 200) %>
# </tr>
# </thead>
#
# - The ascending and descending sort icon images are sort_asc.png and
# sort_desc.png and reside in the application's images directory.
# - Introduces instance variables: @sort_name, @sort_default.
# - Introduces params :sort_key and :sort_order.
#
module SortHelper
# Initializes the default sort column (default_key) and sort order
# (default_order).
#
# - default_key is a column attribute name.
# - default_order is 'asc' or 'desc'.
# - name is the name of the session hash entry that stores the sort state,
# defaults to '<controller_name>_sort'.
#
def sort_init(default_key, default_order='asc', name=nil)
@sort_name = name || params[:controller] + params[:action] + '_sort'
@sort_default = {:key => default_key, :order => default_order}
end
# Updates the sort state. Call this in the controller prior to calling
# sort_clause.
#
def sort_update()
if params[:sort_key]
sort = {:key => params[:sort_key], :order => params[:sort_order]}
elsif session[@sort_name]
sort = session[@sort_name] # Previous sort.
else
sort = @sort_default
end
session[@sort_name] = sort
end
# Returns an SQL sort clause corresponding to the current sort state.
# Use this to sort the controller's table items collection.
#
def sort_clause()
session[@sort_name][:key] + ' ' + session[@sort_name][:order]
end
# Returns a link which sorts by the named column.
#
# - column is the name of an attribute in the sorted record collection.
# - The optional caption explicitly specifies the displayed link text.
# - A sort icon image is positioned to the right of the sort link.
#
def sort_link(column, caption=nil)
key, order = session[@sort_name][:key], session[@sort_name][:order]
if key == column
if order.downcase == 'asc'
icon = 'sort_asc.png'
order = 'desc'
else
icon = 'sort_desc.png'
order = 'asc'
end
else
icon = nil
order = 'desc' # changed for desc order by default
end
caption = titleize(Inflector::humanize(column)) unless caption
params = {:params => {:sort_key => column, :sort_order => order}}
link_to_remote(caption,
{:update => "content", :url => { :sort_key => column, :sort_order => order}},
{:href => url_for(:params => { :sort_key => column, :sort_order => order})}) +
(icon ? nbsp(2) + image_tag(icon) : '')
end
# Returns a table header <th> tag with a sort link for the named column
# attribute.
#
# Options:
# :caption The displayed link name (defaults to titleized column name).
# :title The tag's 'title' attribute (defaults to 'Sort by :caption').
#
# Other options hash entries generate additional table header tag attributes.
#
# Example:
#
# <%= sort_header_tag('id', :title => 'Sort by contact ID', :width => 40) %>
#
# Renders:
#
# <th title="Sort by contact ID" width="40">
# <a href="/contact/list?sort_order=desc&sort_key=id">Id</a>
# <img alt="Sort_asc" src="/images/sort_asc.png" />
# </th>
#
def sort_header_tag(column, options = {})
if options[:caption]
caption = options[:caption]
options.delete(:caption)
else
caption = titleize(Inflector::humanize(column))
end
options[:title]= "Sort by #{caption}" unless options[:title]
content_tag('th', sort_link(column, caption), options)
end
private
# Return n non-breaking spaces.
def nbsp(n)
' ' * n
end
# Return capitalized title.
def titleize(title)
title.split.map {|w| w.capitalize }.join(' ')
end
end
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