Pagination with HABTM relationship

Rails
1

I am wondering how to do pagination on a model that has a HABTM
relationship through a join model.

The models

User
has_many :resources
has_many :pages, :through => :resources
…

Page
has_many :resources
has_many :users, :through => :resources
…

Resource
belongs_to :user
belongs_to :page
…

Then in the PageController I have a list method:
def list
@pages = @user.pages # @user is set with a before_filter

end

This works fine - but I want to be able to paginate the @pages list

So how do I do this? I have read all that I can find regarding
pagination and still am not getting it.

Code is always helpful.

Thanks in advance – K

2

Is this impossible or just not challenging enough to get a responce?
Please enlighten me if you know how to do this.

Thanks in advance – K

3

Kim,

Here are 2 links to plug-ins that others have recommended. I tried the
first one about a month ago and never quite got it working (I can’t
remember what the problem was).

http://codefluency.com/2006/10/24/paginator-released

-Paul

4

On Dec 19, 5:47 pm, “Kim” [email protected] wrote:

Page
def list

Thanks in advance – K

Is the “Custom Pagination” section here helpful?

http://wiki.rubyonrails.org/rails/pages/HowtoPagination

Best,

-r

–
Ryan R.
http://raaum.org
http://rails.raaum.org – Rails docs
http://locomotive.raaum.org – Self contained Rails for Mac OS X

5

The cardboardrocket paginating_find works great for me. Although I had
to make some small changes to get it to work properly… here’s an
example from my code:

@products = Product.find(:all,
:conditions => [ “category_id = ?”, params[:id]],
:order => “name”,
:page => {:size => 20,
:first => 1,
:current => params[:page] || 1 })

Notice the way I handle the :current. anyways hope it helps if you go
that route.

good luck,
Chad

6

Chad - that sounds good. Would you mind sharing a code snippet from
your view as to how you handle the paging? I think that may have been
what I was missing.

Thanks,
Paul

7

Thank you Ryan! The custom pagination worked perfectly.

Here is the code I added to the list method in the controller:

step 1: read and set the variables you’ll need

   page = (params[:page] ||= 1).to_i
   items_per_page = 8
   offset = (page - 1) * items_per_page

step 2: do your custom find without doing any kind of limits or

offsets
@pages = @user.pages

step 3: create a Paginator, the second variable has to be the

number of ALL items on all pages
@which_pages = Paginator.new(self, @pages.length,
items_per_page, page)

step 4: only send a subset of @pages to the view

@pages = @pages[offset..(offset + items_per_page - 1)]
8

On Dec 20, 5:45 pm, “Kim” [email protected] wrote:

   @pages = @user.pages

step 3: create a Paginator, the second variable has to be the

number of ALL items on all pages
@which_pages = Paginator.new(self, @pages.length,
items_per_page, page)

step 4: only send a subset of @pages to the view

@pages = @pages[offset..(offset + items_per_page - 1)]

Mind you, this is not a super efficient method, but as long as the
number of user.pages is not too large it should not impact performance.
Now if users have thousands of pages …

Best,

-r

–
Ryan R.
http://raaum.org
http://rails.raaum.org – Rails docs
http://locomotive.raaum.org – Self contained Rails for Mac OS X