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module ActionController::Rendering

Constants

[:body, :plain, :html]

Public instance methods

Renders a template and assigns the result to self.response_body.

If no rendering mode option is specified, the template will be derived from the first argument.

render "posts/show"
# => renders app/views/posts/show.html.erb

# In a PostsController action...
render :show
# => renders app/views/posts/show.html.erb

If the first argument responds to render_in, the template will be rendered by calling render_in with the current view context.

class Greeting
  def render_in(view_context)
    view_context.render html: "<h1>Hello, World</h1>"
  end

  def format
    :html
  end
end

render(Greeting.new)
# => "<h1>Hello, World</h1>"

render(renderable: Greeting.new)
# => "<h1>Hello, World</h1>"

Rendering Mode

:partial : See ActionView::PartialRenderer for details.

    render partial: "posts/form", locals: { post: Post.new }
    # => renders app/views/posts/_form.html.erb

:file : Renders the contents of a file. This option should not be used with unsanitized user input.

    render file: "/path/to/some/file"
    # => renders /path/to/some/file

:inline : Renders an ERB template string.

    @name = "World"
    render inline: "<h1>Hello, <%= @name %>!</h1>"
    # => renders "<h1>Hello, World!</h1>"

:body : Renders the provided text, and sets the content type as text/plain.

    render body: "Hello, World!"
    # => renders "Hello, World!"

:plain : Renders the provided text, and sets the content type as text/plain.

    render plain: "Hello, World!"
    # => renders "Hello, World!"

:html : Renders the provided HTML string, and sets the content type as text/html. If the string is not html_safe?, performs HTML escaping on the string before rendering.

    render html: "<h1>Hello, World!</h1>".html_safe
    # => renders "<h1>Hello, World!</h1>"

    render html: "<h1>Hello, World!</h1>"
    # => renders "&lt;h1&gt;Hello, World!&lt;/h1&gt;"

:json : Renders the provided object as JSON, and sets the content type as application/json. If the object is not a string, it will be converted to JSON by calling to_json.

    render json: { hello: "world" }
    # => renders "{\"hello\":\"world\"}"

:renderable : Renders the provided object by calling render_in with the current view context. The response format is determined by calling format on the renderable if it responds to format, falling back to text/html by default.

    render renderable: Greeting.new
    # => renders "<h1>Hello, World</h1>"

By default, when a rendering mode is specified, no layout template is rendered.

Options

:assigns : Hash of instance variable assignments for the template.

    render inline: "<h1>Hello, <%= @name %>!</h1>", assigns: { name: "World" }
    # => renders "<h1>Hello, World!</h1>"

:locals : Hash of local variable assignments for the template.

    render inline: "<h1>Hello, <%= name %>!</h1>", locals: { name: "World" }
    # => renders "<h1>Hello, World!</h1>"

:layout : The layout template to render. Can also be false or true to disable or (re)enable the default layout template.

    render "posts/show", layout: "holiday"
    # => renders app/views/posts/show.html.erb with the app/views/layouts/holiday.html.erb layout

    render "posts/show", layout: false
    # => renders app/views/posts/show.html.erb with no layout

    render inline: "<h1>Hello, World!</h1>", layout: true
    # => renders "<h1>Hello, World!</h1>" with the default layout

:status : The HTTP status code to send with the response. Can be specified as a number or as the status name in Symbol form. Defaults to 200.

    render "posts/new", status: 422
    # => renders app/views/posts/new.html.erb with HTTP status code 422

    render "posts/new", status: :unprocessable_entity
    # => renders app/views/posts/new.html.erb with HTTP status code 422
Source code GitHub
# File actionpack/lib/action_controller/metal/rendering.rb, line 165
def render(*args)
  raise ::AbstractController::DoubleRenderError if response_body
  super
end

Similar to render, but only returns the rendered template as a string, instead of setting self.response_body.

Source code GitHub
# File actionpack/lib/action_controller/metal/rendering.rb, line 174
def render_to_string(*)
  result = super
  if result.respond_to?(:each)
    string = +""
    result.each { |r| string << r }
    string
  else
    result
  end
end

Namespace

Definition files