What does `status: :ok` do in `render json:` (Rails)

Question

What doesstatus: :ok do in render json: {round: @round}, status: :ok?

Sometimes everything works without it, but sometimes its necessary to prevent an error like,

ActionController::UnknownFormat (ActionController::UnknownFormat):

I use Angular for front-end and Rails for back-end.

My understanding is that this final line in the Rails controller action converts the server response back to json format so Angular can read it (not 100% confident this is correct explanation).

But I don't understand why to use one or the other of the following. Sometimes one works and sometimes the other does.

1. render json: {round: @round}, status: :ok1
2. respond_to :json and respond_with @round

Can anyone share some insight?

Answer 1

What does status: :ok do in render json:

It means the response will be sent with 200 OK http response code.

Answer 2

The status: :ok in render json: {round: @round}, status: :ok tells the render method to change the status code which is 200 OK by default in the HTTP header (Rendering in Rails Guide). So in case of :ok there should be no difference.

Your method invocation tells the render method to render the hash {round: @round} in json format with the status code 200 OK.

The api dock tells you more about the usage of respond_to which is used to distinguish between different content types while render does the heavy lifting of actually rendering your response.