# module ActionView::Helpers::RenderingHelper

# 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.

### Public Instance Methods

_layout_for(*args, &block) click to toggle source

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>

Calls superclass method

    # File 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) click to toggle source

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.

    # File 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