Question

How can pass multiple parameters using respond_to in rails? When I have more than 1 instance variable, I get an error. But I have an scenario when I have to pass in multiple parameters(instance variables) thru respond_to

Answer 1

respond_to actually is supposed to only return a singular thing. The HTML template renderer is also only returning one thing – but embedding your multiple instance variables into it’s HTML.

So you basically have to do the same for Json and XML: Construct a single object that contains all your data.

An example would be this code:

def show
  @post = Post.first
  @users = Users.where(:active => true)
  respond_to do |format|
    format.html #this will simply render the view
    format.json { render :json => { :post => @post, :users => @users } }
  end
end

Once you want to output these multiple values through Json you have to define a singular Json object that contains what you want to return.

In my example this is a Json object that contains post and users – thus giving the caller the same information as you give the HTML view.

The resulting Json looks like this:

{
  post: {..},
  users: [..]
}

Update:

If you are using this to render javascript where you have a script.js.erb you don’t have to pass anything to the responds_to call but rather can use all instance variables (prefixed by a @) inside your js.erb file like you would in a normal HTML view by using the <%= %> syntax.