Item's page and will_paginate

Question

I have some photos that are split on successive pages through will_paginate plugin. When you open a photo and then return to all photos using a link, you always return to the first page (e.g. the photo is displayed on page 5, you open the photo, click a link to show all photos and expect that you are on page 5 again, but you are on page 1).

Now, is there any method to get the page number to which a photo belongs to?

I tried to pass a GET parameter, but this only works if the user doesn't perform any more actions (e.g. post a comment, edit photo, ecc.).

Answer 1

page = (number_of_records_before_RECORD / number_of_records_per_page) + 1

In other words. If your photo has ID 40 and there are 25 records before (assuming some records have been deleted), with 20 records per page:

page = (25 / 20) + 1 = 2

You can count the number of records before the selected record using Model.count(:conditions => ['id < ?', record.id], :order => 'id'). The right query depends on which sorting filter you apply to that table when listing all objects.

Answer 2

The page number is highly dependent on the results of your search. Your search might have 1, 10, or 100 pages depending on the result set and the number of items per page.

Any link to "show all photos" could contain the search and pagination information, using the GET parameters as you've described. Or store and retrieve via a cookie so that the search results persist until the users clears or selects a new search.

Answer 3

Here's another solution: will_paginate just uses query string parameters 'search_field' and 'page'; you can extract these from the Rails params hash. If you keep track of those using session state, you can reapply them in your controller code, when needed.

Exactly how you manage that will depend on your application. In the app I'm working on, the flow is such that I can distinguish between a general context and a member context. The user enters the member context from the member#index page. So I just set session[:member_context] on entry to the member context; e.g. in members#edit. Then, in the members#index, I have the following code:

if session[:member_context]
  @search_field = session[:search_field]
  @page = session[:page]
  # toggle out of member context
  session[:member_context] = nil
else
  @search_field = params[:search_field]
  @page = params[:page]
  # record lastest search in case the user subsequently enters the member context
  session[:search_field] = @search_field
  session[:page] = @page
end
@members = Member.where(<use @search_field>).page(@page)
# and render ...

This works great in my application.