Still need explicit format html when render partial in turbo stream about turbo-rails

[chloerei]

But I found a document say that format is automatically switched:

code:

turbo-rails/app/models/turbo/streams/tag_builder.rb

Lines 14 to 17 in 79b5ffd

	# <%= turbo_stream.append "entries" do %>
	# <% # format is automatically switched, such that _entry.html.erb partial is rendered, not _entry.turbo_stream.erb %>
	# <%= render partial: "entries/entry", locals: { entry: entry } %>
	# <%= end %>

commit: 969d899

Did I misunderstand?

[scomma]

I'd like to request a reopening of this issue.

Currently this results in an unintuitive behavior where if you have a controller action do implicit rendering to a Turbo Stream template, and that template renders (via a standard render method) an HTML partial, the format switching happens automatically.

Once you so much as add respond_to to the controller action, that format switching turns off, and you have to modify the render call inside the first template to explicitly request the HTML partial.

Illustration below. Hope this makes sense.

Works

x_controller.rb

  def new
  end

new.turbo_stream.erb

render 'form', x: ...

_form.html.erb

<form>...

Breaks

x_controller.rb

  def new
    respond_to do |format|
      format.turbo_stream
      format.html { redirect_to ... }
    end
  end

new.turbo_stream.erb

render 'form'

_form.html.erb

<form>...

Workaround

x_controller.rb

  def new
    respond_to do |format|
      format.turbo_stream
      format.html { redirect_to ... }
    end
  end

new.turbo_stream.erb

render partial: 'form', formats: :html, locals: { x: ... }

_form.html.erb

<form>...

[kylekeesling]

@chloerei you may have already figured this out but the docs you are referring to reference the call that DHH mentioned, meaning if you use the turbo_stream.append helper you get the format switching "automatically", but if you are using the standard render call you'll need to explicity define formats: [:html]

[dhh]

That is the correct behavior in the sense that the turbo stream template is assuming all partials will also be turbo stream templates, unless you change that. We have a helper when you do the inline call, though:

<%= turbo_stream.append 'messages', @message %>

It also work with the partial options:

<%= turbo_stream.append 'messages', partial: "messages/message" %>

But if you call your own render partial, you need to add the formats options.

Feel free to look at a doc change to make this clearer.

[joshmfrankel]

As @kylekeesling mentions above, a standard render call requires the format to be explicitly defined. For example, a failure case from form submission may look like:

render :show, status: :unprocessable_entity, formats: :html

Reason being the resulting error: ActionView::MissingTemplate indicates that it is trying to render :formats=>[:turbo_stream] which if you only have the HTML template it isn't going to work. (what DHH said above) Hence the above explicit definition is necessary