Rails: Using will_paginate with a complex association find

Question

I\'m encountering a problem with will_paginate while doing a complex find.

:photo  has_many   :tags,   :through => :tagships
:item   has_many   :photos
:p         


        

Answer 1

My first stab at this (sorry don't have time to test it right now... will update if I do) would be something like the following (added the :select and changed the :group):

@photos = @item.photos.paginate :page => params[:page],
                                :per_page => 200,
                                :select => "photos.*, COUNT(DISTINCT tags.id) AS tag_count",
                                :conditions => [ 'tags.id IN (?)', tag_ids ],
                                :order => 'created_at DESC',
                                :joins => :tags,
                                :group => "photos.id HAVING tag_count = #{tag_count}"

Answer 2

FYI, here's what I finally found to fix this:

@photos = WillPaginate::Collection.create(current_page, per_page) do |pager|
    result = @item.photos.find :all, :conditions => [ 'tags.id IN (?)', tag_ids] ,:order => 'created_at DESC', :joins => :tags, :group => "photos.id HAVING COUNT(DISTINCT tags.id) = #{@tags.count}", :limit => pager.per_page, :offset => pager.offset
    pager.replace(result)

    unless pager.total_entries
      pager.total_entries = @item.photos.find(:all, :conditions => [ 'tags.id IN (?)', tag_ids] ,:order => 'created_at DESC', :joins => :tags, :group => "photos.id HAVING COUNT(DISTINCT tags.id) = #{@tags.count}").count
    end
  end

You have to manually construct the paginated set using the page number as an offset and using the tags to make a join query. Kinda clunky.