Beginner Layouts and Partials question

Hello - very new to rails and MVC, I'm trying to figure out how layouts/partials co-exist. My basic layout (application.html.erb) looks like this:

<body>   <div id="wrapper">     <%= render :partial => "main/header" %>     <div id="content">       <%= render => :partial => "main/menu" %>       <%= render => :partial => @partial %>     </div>   </div> </body>

and my MainController is:

class MainController

  def index     @partial = "main/home"   end

end

Now, I found that I have to create an index.html.erb file that's identical to the application.html.erb file, or nothing works (neither can exist without the other). I'm trying to understand what I'm doing wrong -- obviously I need some index action in my controller, but I'd like to just maintain one layout file and nothing else.. I'm obviously missing something big here, so any clarifications will be great :slight_smile:

right: you need an index-file for your index-action (actions and views pair up) wrong: it has not to be identical to the layout-file.

try to put   <%= yield %> into your layout instead of   <%= render => :partial => @partial %> and change your index to   Hello it's <%= Time.now %>

in your controller just leave it like this   def index   end

now, if you want to render a partial, do so by saying it for example in your view. if you put   render :partial => foo in your controller, then by default   layout => false is set.

maybe i'm even mistaken somewhere, but anyhow i hope i could help. my suggestion: get hold of some rails basics.

Here it goes....

A layout is like the container for the content(.. view) relating to your actions. When an action is called, the action renders its view. For example, the person controllers index action will look for app/ views/person/index.html.erb. It also looks for the layout it should render the view in. You can define the layout to use either in the controller (layout 'application' in your case) or put in in application.rb, which will then define a global default layout.

You've got the right idea with the erb you posted. You can render partials in layouts, but for the action to render it's view in the layout, you need to put <%= yield %>. The entire contents of the actions's view will get rendered there.

Your layout, application.html.erb should be residing in the app/views/ layout directory. You should add "layout 'application'" to your controller, add <%= yield %> to the layout, create views for your actions and try it out. Your views should render inside your layout.

I hope that gives you some idea of how views and layouts interact.

- John

Those were really helpful posts -- I think I got the general idea, in which I should specify in the controller which layout it should belong to, and then in the layout file use <%= yield %> to render these views. I'll keep playing with it and see what comes up.

Thanks!

sa 125 wrote:

Those were really helpful posts -- I think I got the general idea, in which I should specify in the controller which layout it should belong to, and then in the layout file use <%= yield %> to render these views. I'll keep playing with it and see what comes up.

Thanks!

Take this example:

app/controllers/people_controller.rb:

class PeopleController < ApplicationController   # layout 'custom'

  # GET /people   # GET /people.xml   def index     @people = Person.find(:all)

    respond_to do |format|       format.html # index.html.erb       format.xml { render :xml => @people }     end   end end

app/views/layouts/application.html.erb:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd&quot;&gt;

<html xmlns="http://www.w3.org/1999/xhtml&quot; xml:lang="en" lang="en"> <head>   <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>   <title>My Application</title> </head> <body>   <h1>Header in Application layout</h1>   <%= yield %>   <p>Footer in layout</p> </body> </html>

app/views/layouts/people.html.erb:

Robert Walker wrote:

layout by first looking in app/layouts/ for a layout template named

Correction app/views/layouts/

You may also want to read the getting started guide (and others) on http://guides.rubyonrails.org

These were all really helpful -- I really appreciate the depth of the responses. I now only have a problem with using a collection in rendering a partial. I think I followed the exact rules, but here is what I did anyway:

The layout (app/views/layouts/application.html.erb): ... <body>   <%= yield :title %>   <br />   <%= yield %> </body> ...

the controller (app/controllers/people/people_controller.rb):

class PeopleController < ApplicationController   layout "application" # default, but specified anyway   def index     @people = Person.find(:all)   end end

in the view (app/views/people/index.html.erb):

<% content_for :title do -%>   <h3>Listing People</h3> <% end -%>

<table>   <tr>     <th>First Name</th>     <th>Last Name</th>   </tr>   <%= render :partial => "people", :collection => @people %> </table>

in the partial (app/views/people/_people.html.erb):

<tr class=<%= cycle("odd","even")%>>   <td><%= h person.first_name %></td>   <td><%= h person.last_name %></td> </tr>

I realize the partial doesn't recognize the person object, but I thought rails handled the conversion between the collection @people of the view to the iteration in the partial. So.. I'm not sure what I might be doing wrong. Help is very appreciated - thanks!

i don't see an iteration. try

  for person in people do     <tr class=<%= cycle("odd","even")%>>       <td><%= h person.first_name %></td>       <td><%= h person.last_name %></td>     </tr>   end

in the view (app/views/people/index.html.erb):

<% content_for :title do -%>   <h3>Listing People</h3> <% end -%>

<table>   <tr>     <th>First Name</th>     <th>Last Name</th>   </tr>   <%= render :partial => "people", :collection => @people %> </table>

in the partial (app/views/people/_people.html.erb):

<tr class=<%= cycle("odd","even")%>>   <td><%= h person.first_name %></td>   <td><%= h person.last_name %></td> </tr>

----

I made sure I had data available for these people (using script/console), but I got an error rendering this partial:

undefined local variable or method 'person' for #<ActionView::....>

in app/views/people/_people.html.erb

OK, I figured out my mistake - when creating the partial, I called it "_people.html.erb" instead of "_person.html.erb", so the rails engine probably didn't know what to look for. Also needed to change the call to render from <%= render :partial => "people" ....%> to <%= render :partial => "person"...%>

I would like to know how to override this behavior so that I could call the partial and the collections however I want. Thanks to everyone who helped on this post!

sa 125,

This paper (Modular Page Assembly in Rails) helps a lot:

http://www.railsdev.ws/blog/3/modular-page-assembly-in-rails/

Cheers, Sazima