Check for double render errors and set the content_type after rendering.
--

# => 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
render "posts/new", status: 422

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

# => renders "

Hello, World!

" with the default layout
render inline: "

Hello, World!

", layout: true

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

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

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

# => renders "

Hello, World!

"
render inline: "

Hello, <%= name %>!

", locals: { name: "World" }

Hash of local variable assignments for the template.
[+:locals+]

# => renders "

Hello, World!

"
render inline: "

Hello, <%= @name %>!

", assigns: { name: "World" }

Hash of instance variable assignments for the template.
[+:assigns+]

==== Options

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

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

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

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

Hello, World!

"

# => renders "

Hello, World!

"
render html: "

Hello, World!

".html_safe

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

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

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

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

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

# => renders "

Hello, World!

"
render inline: "

Hello, <%= @name %>!

"
@name = "World"

Renders an ERB template string.
[+:inline+]

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

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

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

See ActionView::PartialRenderer for details.
[+:partial+]

==== \Rendering Mode

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

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

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

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

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

def render(*args)
  raise ::AbstractController::DoubleRenderError if response_body
  super
end