Pass Parameters in Link_To

Rails - passing parameters in link_to

First of all, link_to is a html tag helper, its second argument is the url, followed by html_options. What you would like is to pass account_id as a url parameter to the path.
If you have set up named routes correctly in routes.rb, you can use path helpers.

link_to "+ Service", new_my_service_path(:account_id => acct.id)

I think the best practice is to pass model values as a param nested within :

link_to "+ Service", new_my_service_path(:my_service => { :account_id => acct.id })

# my_services_controller.rb
def new
  @my_service = MyService.new(params[:my_service])
end

And you need to control that account_id is allowed for 'mass assignment'. In rails 3 you can use powerful controls to filter valid params within the controller where it belongs. I highly recommend.

http://apidock.com/rails/ActiveModel/MassAssignmentSecurity/ClassMethods

Also note that if account_id is not freely set by the user (e.g., a user can only submit a service for the own single account_id, then it is better practice not to send it via the request, but set it within the controller by adding something like:

@my_service.account_id = current_user.account_id 

You can surely combine the two if you only allow users to create service on their own account, but allow admin to create anyone's by using roles in attr_accessible.

hope this helps

How to pass parameters with link_to tag?

You're already doing it correctly in the controller, you just need to include the :id in the link_to url options:

<%= link_to(:controller => "posts", :action => "up vote", :id => @post) do %>
    <span>Like</span>
    <span>(<%= @post.get_upvotes.size %>)</span>
<% end %>

Note: you don't need to call id on the post, rails will automatically figure this out for you.

A better solution, would be to use resource routes for you Post object. then add upvote/downvote actions:

# in config/routes.rb
resources :posts do
    member do
        match "upvote", :as => :upvote, :via => [:get, :put]
    end
end

Rails will automatically create url helpers that you can use in your views

# in show html.erb
<%= link_to(upvote_post_url(@post)) do %>
    <span>Like</span>
    <span>(<%= @post.get_upvotes.size %>)</span>
<% end %>

the advantage to this is simpler code, and the ability change your routes with having to update template code.

Rails has already done all the heavy lifting of how to make and link to urls, to be faster at plumbing rails views and controllers together, you should definitely read the official guides http://guides.rubyonrails.org/routing.html, then may look daunting at first, but they will quickly become second knowledge.

link_to send parameters along with the url and grab them on target page

Just add them to link:

<%= link_to "Add Product", '/pages/product?param1=value1¶m2=value2' %>

and in controller:

param1 = params[:param1] # "value1"
param2 = params[:param2] # "value2"

If you use helper methods for routes (for example company_path), then you can add hash of params, so this two should be similar:

<%= link_to "Add Product", new_product_path(:param1 => "value1", :param2 => "value2") %>
<%= link_to "Add Product", "/products/new?param1=value1¶m2=value2" %>

From documentation:

link_to "Comment wall", profile_path(@profile, :anchor => "wall")
# => <a href="/profiles/1#wall">Comment wall</a>

link_to "Ruby on Rails search", :controller => "searches", :query => "ruby on rails"
# => <a href="/searches?query=ruby+on+rails">Ruby on Rails search</a>

link_to "Nonsense search", searches_path(:foo => "bar", :baz => "quux")
# => <a href="/searches?foo=bar&baz=quux">Nonsense search</a>

Ruby on Rails - passing parameters in link_to with if conditions?

Conditionally pass a hash, containing additional params for this_link_path url helper.

<%= link_to "This is a link", this_link_path( ({company: params[:company] } if params[:company]) ), class: tl(this_link_path) %>

To be more concise you can compact the hash.

<%= link_to "This is a link", this_link_path({company: params[:company]}.compact), class: tl(this_link_path) %>

If you know that you'll need it more often, wrap this_link_path call in a custom helper. Hash can contain additional params, including ones with fixed values.

def this_link_with_additional_params_path
  this_link_path({company: params[:company], name: 'test'}.compact) 
end

Then in view you can use:

<%= link_to "This is a link", this_link_with_additional_params_path, class: tl(this_link_path) %>

Pass additional parameters with link_to

I resolved my problem. Make sure the value you give to your additional parameters is something. When I go to the news index page, even though the selected page is the first one, there is no parameter page=1. The parameter only appears once click on a different page (or you go to another page and come back to the first one). If you give an additional parameter to the link_to and its value is nothing, the rendered link will be (in my case):

<a href="/news/2" />

Instead of:

<a href="/news/2?back_page=" />

So you might get trapped, just like I was.

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