Using Rails link_to for links that post

I have a link that I need to submit a post request with. Normally, I'd use jQuery and prevent the link's default behavior and then submit a form to the destination. This seems like something Rails should be able to help me out with. Sure enough, the link_to method has an option for specifying a POST http method:

link_to "Profile", 'http://example.com/profile', method: :post

That works, but I need to add 2 parameters too. I tried:

link_to "Profile", 'http://example.com/profile', method: post, param1: 'value1', param2: 'value2'

That just added those parameters to the <a> HTML element, but didn't submit those when clicking the link:

<a rel="nofollow" param1="value1" param2="value2" data-method="post" href="http://example.com/profile">Profile</a>

Is there a way to do a POST request with parameters using link_to or any other Rails method? I'm using Rails 3.2.9.

The short answer is that if what you mean by "parameters" is form fields, then you simply can't do this (at least not in a straightforward way that I can see). You should instead use a form with a submit button, styled to look like a link (if that's what you want it to look like).

If on the other hand you had meant query parameters, then this would work:

link_to "Profile", profile_path(@profile.id, param1: 'value1', param2: 'value2'), method: :post

Note that if the user has JS disabled or you have removed the unobtrusive JS libraries that come by default, link_to will be silently submitted via a GET request.

In general, I am not very fond of having links that perform POST requests. I think that's the role of a form and a button.

Thus, an easy (and safer) alternative is to use the Rails button_to helper:

button_to 'Profile', profile_path(@profile, param1: 'value1', param2: 'value2')

button_to also supports the method option but as it defaults to post so I've just omitted it.

You can encode parameters in the URL this way :

link_to "Profile", 'http://example.com/profile?' + {param1: 'value1', param2: 'value2'}.to_param, method: :post

If it does not fit your needs you are better use a form than a link_to.

In order to POST data, you need a form. However, you don't need a submit button. If you want this to look like a link for some reason, you can actually make it a link that submits the form via JavaScript. In the example below, the POST resource is just a REST action that does not require any fields so there are no form input controls. If you wanted to post some data, just put hidden input fields in the form.

<%= form_tag('http://something_postable', :method => :post, :class => 'internal') %></form>
<%= link_to_function('Label for Link', 'previous("form").submit()', :title => 'Hover text for link') %>

The form is assigned a class so you can style it or hide it via CSS (e.g. 'display: inline')

The parameters and the http method should be together {param1: 'value1', param2: 'value2', :method: :post}

<%= link_to "Profile", profile_path(@profile), {param1: 'value1', param2: 'value2', method: :post} %>