How to have a variable persist from a controller, to a js file, to a rendered partial

Question

I'm rendering a partial viewer using ajax and jQuery. I want to set a variable within the partial, based on the link that is clicked on.

ERB:

<%=link_to "link1", viewer_path(id: Painting.first), remote: true%>
<%=link_to "link2", viewer_path(id: Painting.last), remote: true%>

Controller:

  def viewer
    @painting = Painting.find_by(:id)
    respond_to do |format|
      format.html { redirect_to root_path }
      format.js
    end
  end

viewer.js.erb

$("#viewer").html("<%= escape_javascript(render 'viewer') %>");

_viewer.html.erb

<%= @painting.name %>

But the variable @painting isn't set when the partial is rendered so I get an error.

Shouldn't defining the variable in the controller have the value carry though to the partial? What am I doing wrong?

Answer 1

This may be your problem: when using Model.find_by, you need to specify what you are finding by. Try using Model.find, which always uses the Model's :id, or Model.find_by_id or Model.find_by(id: :id).

Make this update in controller#viewer:

@painting = Painting.find(:id)

You are right though, instance variables (@painting) are usable in partials.