How to add parameters to current URL in rails [duplicate]

This question already has answers here: Add querystring parameters to link_to (5 answers) Closed 8 years ago.

I have a logic where I allow sorting on price and relevance. I am doing this by passing parameters to controller. My URL has a parameter - 'sort' which can have a value - 'price_lowest' or 'default'. The links looks like:

<a href="<%= request.fullpath + '&sort=price_lowest' %>">lowest prices</a> | 
<a href="<%= request.fullpath + '&sort=default' %>">relevance</a>

problem with the above code is that it "adds" parameters and does not "replace" them. I want to replace the value of &sort= parameter without adding a new value. E.g. I don't want :

../&sort=price_lowest&sort=price_lowest&sort=default

With the current l开发者_JAVA百科ogic - I am getting the above behaviour. Any suggestions ?

---

In order to preserve the params I did this:

<%= link_to 'Date', params.merge(sort: "end_date") %>

However the url will be ugly.

UPDATE

For Rails 5 use:

<%= link_to 'Date', request.params.merge(sort: "end_date") %>

---

If you only need one cgi param and want to stay on the same page, this is very simple to achieve:

<%= link_to "lowest prices", :sort => "price_lowest" %>

However, if you have more than one, you need some logic to keep old ones. It'd probably be best extracted to a helper, but essentially you could do something like this to keep the other params..

<%= link_to "lowest prices", :sort => "price_lowest", :other_param => params[:other] %>

Named routes will only really help you here if you need to go to another page.

---

If a path is not passed to the link_to method, the current params are assumed. In Rails 3.2, this is the most elegant method for adding or modifying parameters in a URL:

<%= link_to 'lowest prices', params.merge(sort: 'end_date') %>
<%= link_to 'relevance', params.merge(sort: 'default') %>

params is a Ruby hash. Using merge will either add a key or replace the value of a key. If you pass nil as the value of a key, it will remove that key/value pair from the hash.

<%= link_to 'relevance', params.merge(sort: nil) %>

Cite:

• link_to http://apidock.com/rails/ActionView/Helpers/UrlHelper/link_to
• url_for http://apidock.com/rails/v3.2.13/ActionView/Helpers/UrlHelper/url_for

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My working solution on Rails 3.1 of course, it's hardcode, and has to be refactored.

item model

  def self.get(field,value)
    where(field=>value)
  end

items controller

@items=Item.all
 if params[:enabled]
  @items=@items.get(:enabled, params[:enabled])
end
if params[:section]
  @items=@items.get(:section_id, params[:section])
end

items helper

def filter_link(text, filters={}, html_options={})
  trigger=0
  params_to_keep = [:section, :enabled]
  params_to_keep.each do |param|
    if filters[param].to_s==params[param] && filters[param].to_s!="clear" || filters[param].to_s=="clear"&&params[param].nil?
      trigger=1
    end
    if filters[param]=="clear"
      filters.delete(param)
    else
      filters[param]=params[param] if filters[param].nil?
    end
  end
  html_options[:class]= 'current' if trigger==1
  link_to text, filters, html_options
end

items index.html.erb

<%= filter_link 'All sections',{:section=>"clear"} %>
<% @sections.each do |section| %>
   <%= filter_link section.title, {:section => section} %>
<% end %>

<%= filter_link "All items", {:enabled=>"clear"} %>
<%= filter_link "In stock", :enabled=>true %>
<%= filter_link "Not in stock", :enabled=>false %>

---

It's not quite the answer to the question that you're asking, but have you thought about using the Sorted gem to handle your sorting logic and view links?