Rails AJAX error

Question

I have:

<p id="click">Click here</p> 

In contorller:

def index
    @all=Person.all
    @person=Person.where(id: params[:id])
    respond_to do |format|
       format.html
       format.js
    end
end

and:

$('#click').on('click',function(){
     $.ajax({
              type: "POST",
              data: 'id='+id,    
              url: "/index"  
          });
    }  

index.js.erb

$("#show").html("<%= escape_javascript(render(@person))%>");  

_persons.html.erb

<h3><%= @person.name %></h3>  

index.html.erb

    <div id="show">
      <%= render @person %>
    </div>    

routes

get '/index', to: "main#index" put '/index', to: "main#index"

Now when I got to the index action I get

Person not found with id = nil

Before even the page is loaded. Why is the @person instance variable executed directly? I'm not even able to get to the index page. How does rails ajax work? How does it know the @person variable is to be executed via ajax?

Answer 1

It's not an Ajax error. It's a normal Rails error. You're doing:

@person=Person.where(id: params[:id])

But in the the index action there is no params[:id], so what you're actually doing is:

@person = Person.where(id: nil)

That's what the error is about.

The main problem is that you're trying to do two things in one action. You should make a separate action for the Ajax call:

def index
  @all = Person.all
end

def ajax_call
  @person = Person.where(id: params[:id])

  respond_to do |format|
    format.html
    format.js
  end
end

$('#click').on('click',function(){
  $.ajax({
    type: "POST",
    data: 'id='+id,    
    url: "/ajax_call"  
  });
}

Something like this. You'll need to add a route for the ajax_call action, but this is the idea.