Geek Answers Handbook

Rails: using will_paginate with complex find association

I am facing a problem with will_paginate when doing a complicated find.

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


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

I want to get all the photos that have all the tags in the tag_ids array. MySQL IN usually does a "or" search, but I need a "and". I found how to change IN to mimic the "and" behavior of here , and it works fine when using model.find (), also works as long as the number of posts is calculated below mine: per_page count. But if it should be paginated, the generated SQL is like:

SELECT count(*) AS count_all, photos.id HAVING COUNT(DISTINCT tags.id) = 1 AS photos_id_having_count_distinct_tags_id_1 FROM `photos`(...)

which does not work. Others saw this error and were able to transfer their account () from the request, but I do not think this is possible in my case.

, will_paginate? , , ?

!

+5
2

FYI, , , , :

@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

, , , . .

+4

(, ... , ) - (: select changed: 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}"
+1

More articles:


All Articles