Rails: Preserving GET query string parameters in link_to

Question

I have a typical search facility in my app which returns a list of results that can be paginated, sorted, viewed with a different records_per_page value, etc. Each of these options is controlled by parameters in the query string. A simplified example:

/search?q=test&page=2

Now say I need to display a set of links that set records_per_page value to 10, 20, 30. Each link must include the existing query parameters, which can be a very long set, plus a new per_page parameter.

/search?q=test&page=2& ... &per_page=10
/search?q=test&page=2& ... &per_page=20
/search?q=test&page=2& ... &per_page=30

Is there an easy way to do it with just link_to helper or I need to parse and reproduce the query string from previous request somehow?

possible duplicate of [Add querystring parameters to link\_to](http://stackoverflow.com/questions/2695538/add-querystring-parameters-to-link-to) — Ciro Santilli OurBigBook.com, Oct 01 '14 at 13:24

score 75 · Accepted Answer · edited Nov 21 '16 at 11:42

75

link_to 'Link', request.query_parameters.merge({:per_page => 20})

edited Nov 21 '16 at 11:42

Simon B.

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answered Sep 21 '10 at 19:17

Vincent

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This adds some 'extra' parameters like `controller` and `action`. – kikito Aug 19 '15 at 22:31
14

But you can avoid that by using `request.query_parameters` instead of `request.parameters` – kikito Aug 19 '15 at 22:49
2

use `deep_merge` if your query parameters require associated arrays or nested hash – Tun Mar 09 '17 at 17:41

score 22 · Answer 2 · answered Nov 13 '10 at 20:20

22

link_to 'Link', params.merge({:per_page => 20})

answered Nov 13 '10 at 20:20

Olek

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score 19 · Answer 3 · answered Jan 06 '15 at 19:43

The simplest way to merge the new params with the query parameters and NOT with all parameters (including those obtained through the path) is to merge with request.query_parameters

link_to 'Search', search_path(request.query_parameters.merge({ per_page: 20 }))

Otherwise you end up with query strings duplicating the path parameters, for example ?action=index&controller=products&foo=bar instead of ?foo=bar.

score 4 · Answer 4 · answered May 10 '14 at 07:44

If you want to keep existing params and not expose yourself to XSS attacks, be sure to clean the params hash, leaving only the params that your app can be sending:

# inline
<%= link_to 'Link', params.slice(:sort).merge(per_page: 20) %>

If you use it in multiple places, clean the params in the controller:

# your_controller.rb
@params = params.slice(:sort, :per_page)

# view
<%= link_to 'Link', @params.merge(per_page: 20) %>

score 2 · Answer 5 · answered Jun 19 '12 at 19:22

This works if the links you are processing aren't given to you by request.params.

require 'rack/utils'                                                                                
require 'uri'                                                                                       

def modify_query url, options={}                                                                    
  uri = URI(url)                                                                                    
  query_hash = Rack::Utils.parse_query(uri.query)                                                   
  query_hash.merge!(options)                                                                        
  uri.query = Rack::Utils.build_query(query_hash)                                                   
  uri.to_s                                                                                          
end                                                                                                 

puts modify_query('/search?q=test&page=2&per_page=10', 'per_page' =>  20)                           
puts modify_query('/search?q=test&page=2', 'per_page' => 30)                                        

# Outputs                                                                                           
# /search?q=test&page=2&per_page=20                                                                 
# /search?q=test&page=2&per_page=30

score 2 · Answer 6 · answered Sep 21 '10 at 16:47

2

You can just throw elements of the params hash at link_to. Like

link_to "some_other_link", "/search", :page => params[:page]

answered Sep 21 '10 at 16:47

Reactormonk

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score 1 · Answer 7 · answered Sep 21 '10 at 18:26

1

What about

<%= link_to 'Whatever', :overwrite_params => { :pear_page => 20 } %>

?

answered Sep 21 '10 at 18:26

jordinl

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This looks just like what I was looking for. However it's deprecated in Rails 3. link_to 'link', request.parameters.merge({:per_page => 20}) worked for me. – Vincent Sep 21 '10 at 19:14
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What is the rails 3.2+ way to do this? – coudron Jun 26 '13 at 06:30

complistic · Answer 8 · 2011-06-07T02:13:01.697

A bit late i know..

If your using this as a way to filter search results have a look at my helper :)

This automagicly removes all blank and unneeded params and add the class "selected" if all of it's new params were already set.

def search_to s, args={}

  selected = 0
  args.each do |k, v|
    selected = selected + 1 if params[k] == v.to_s || ( params[k].nil? && v.blank? )
  end

  if @search_params_base.nil?
    @search_params_base = request.parameters.clone
    @search_params_base.delete(:action)
    @search_params_base.delete(:controller)
    @search_params_base.delete(:page)
    @search_params_base.delete_if{|k, v| v.nil? || v.blank?}
    @search_params_base.delete(:utf8) if @search_params_base[:keywords].nil?
  end
  search_params = @search_params_base.merge(args)
  search_params.delete_if{|k, v| v.nil? || v.blank?}

  link_to s, search_path + '?' + search_params.to_param, :class => selected == args.length ? 'selected' : nil
end

You can then just use this in your view:

search_to '$80 to $110', :price => 80..110

Or in your case:

search_to '30 per page', :page => params[:page], :per_page => 30

Rails: Preserving GET query string parameters in link_to

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