Action View Rendering

Implements methods that allow rendering from a view context. In order to use this module, all you need is to implement view_renderer that returns an ActionView::Renderer object.

Methods
#
R
Instance Public methods
_layout_for(*args, &block)

Overwrites #_layout_for in the context object so it supports the case a block is passed to a partial. Returns the contents that are yielded to a layout, given a name or a block.

You can think of a layout as a method that is called with a block. If the user calls yield :some_name, the block, by default, returns content_for(:some_name). If the user calls simply yield, the default block returns content_for(:layout).

The user can override this default by passing a block to the layout:

# The template
<%= render :layout => "my_layout" do %>
  Content
<% end %>

# The layout
<html>
  <%= yield %>
</html>

In this case, instead of the default block, which would return content_for(:layout), this method returns the block that was passed in to render :layout, and the response would be

<html>
  Content
</html>

Finally, the block can take block arguments, which can be passed in by yield:

# The template
<%= render :layout => "my_layout" do |customer| %>
  Hello <%= customer.name %>
<% end %>

# The layout
<html>
  <%= yield Struct.new(:name).new("David") %>
</html>

In this case, the layout would receive the block passed into render :layout, and the struct specified would be passed into the block as an argument. The result would be

<html>
  Hello David
</html>

Source: show | on GitHub 

# File actionpack/lib/action_view/helpers/rendering_helper.rb, line 79
def _layout_for(*args, &block)
  name = args.first

  if block && !name.is_a?(Symbol)
    capture(*args, &block)
  else
    super
  end
end
render(options = {}, locals = {}, &block)

Returns the result of a render that’s dictated by the options hash. The primary options are:

  • :partial - See ActionView::PartialRenderer.

  • :file - Renders an explicit template file (this used to be the old default), add :locals to pass in those.

  • :inline - Renders an inline template similar to how it's done in the controller.

  • :text - Renders the text passed in out.

If no options hash is passed or :update specified, the default is to render a partial and use the second parameter as the locals hash.

Source: show | on GitHub 

# File actionpack/lib/action_view/helpers/rendering_helper.rb, line 18
def render(options = {}, locals = {}, &block)
  case options
  when Hash
    if block_given?
      view_renderer.render_partial(self, options.merge(:partial => options[:layout]), &block)
    else
      view_renderer.render(self, options)
    end
  else
    view_renderer.render_partial(self, :partial => options, :locals => locals)
  end
end