Where is the documentation on url helpers in rails?

Question

How do I know what arguments url helpers take in Rails? For example, how do I know url helper takes just one parameter below? I know these methods are metaprogrammed but where is their documentation?

link_to "New Ticket", new_project_ticket_path(@project)

Answer 1

You can determine how many parameters a route helper requires by looking at the route definition.

For example, you might have this routes file:

resources :users

If you ran rake routes at the command line you would see something like this:

    users GET    /users(.:format)          users#index
          POST   /users(.:format)          users#create
 new_user GET    /users/new(.:format)      users#new
edit_user GET    /users/:id/edit(.:format) users#edit
     user GET    /users/:id(.:format)      users#show
          PUT    /users/:id(.:format)      users#update
          DELETE /users/:id(.:format)      users#destroy

The first column gives you the name of the route. You can append _path or _url to get the name of a route helper.

The third column shows the pattern. This is where you can figure out what the arguments are. Arguments are the parts prefixed with a colon, and optional arguments are shown in parentheses. For example the edit_user route has the pattern /users/:id/edit(.:format) which contains one required argument (id) and one optional argument (format), which tells me I need to pass at least one argument to the edit_user_path or edit_user_url helper:

edit_user_path(1) # => "/users/1/edit"
edit_user_path(2, :html) # => "/users/2/edit.html"

You can also use the argument names from the pattern as keys in a hash:

edit_user_path(id: 3, format: 'js') # => "/users/3/edit.js"

Finally, you can add extra arguments which will become part of the query string:

edit_user_path(id: 4, format: 'json', foo: 1) # => "/users/4/edit.json?foo=1"
edit_user_path(5, bar: 2) # => "/users/5/edit?bar=2"

See the Rails Routing Guide's section on Listing Existing Routes for more information about rake routes.

Answer 2

Here is the API doc. It contains link_to, button_to, link_to_unless, link_to_unless_current, current_page?, and mail_to.

link_to(name = nil, options = nil, html_options = nil, &block)

link_to(body, url, html_options = {})
# url is a String; you can use URL helpers like posts_path

Options

:data - This option can be used to add custom data attributes.

method: symbol of HTTP verb - This modifier will dynamically create an HTML form and immediately submit the form for processing using the HTTP verb specified. Useful for having links perform a POST operation in dangerous actions like deleting a record (which search bots can follow while spidering your site). Supported verbs are :post, :delete, :patch, and :put. Note that if the user has JavaScript disabled, the request will fall back to using GET. If href: '#' is used and the user has JavaScript disabled clicking the link will have no effect. If you are relying on the POST behavior, you should check for it in your controller's action by using the request object's methods for post?, delete?, :patch, or put?.

remote: true - This will allow the unobtrusive JavaScript driver to make an Ajax request to the URL in question instead of following the link. The drivers each provide mechanisms for listening for the completion of the Ajax request and performing JavaScript operations once they're complete

Data attributes

confirm: 'question?' - This will allow the unobtrusive JavaScript driver to prompt with the question specified. If the user accepts, the link is processed normally, otherwise no action is taken.

:disable_with - Value of this parameter will be used as the value for a disabled version of the submit button when the form is submitted. This feature is provided by the unobtrusive JavaScript driver.

Answer 3

I usually refer to Rails Routing Guide