The key lies in how paginate pages the data. For an ActiveRecord source, it generates the following ARel modifiers:
        offset          how many records to skip before starting collection
        limit                   how many records to include in the collection

will_paginate's default processing is to use offset => (pager.offset) and limit => (pager.per_page), but what you want is  offset => (pager.page - 1), limit => (pager.per_page).  This can be accomplished by performing manual paging, as documented with WillPaginate::Collection:

    # Just like +new+, but yields the object after instantiation and returns it
    # afterwards. This is very useful for manual pagination:
    #
    #   @entries = WillPaginate::Collection.create(1, 10) do |pager|
    #     result = Post.find(:all, :limit => pager.per_page, :offset => pager.offset)
    #     # inject the result array into the paginated collection:
    #     pager.replace(result)
    #
    #     unless pager.total_entries
    #       # the pager didn't manage to guess the total count, do it manually
    #       pager.total_entries = Post.count
    #     end
    #   end

There may be an easier way to accomplish this -- let's see what  others say.

On Feb 10, 2012, at 7:36 PM, Rembrant wrote: