Use to_json when rendering json response

I was trying to debug why an inertia response was 5x slower than the initial page response.

After some investigation, it turns out that render json: foo does not actually do the same thing as foo.to_json does. It does a whole lot of rails magic instead, which is both a lot slower and inconsistent.

Changing this to use page.to_json ensures consistency with the props output in inertia.html.erb, avoiding weird inconsistencies between props renders and full page renders, and is also a lot faster (especially if you are using a library like Oj to optimise json generation in the first place).

lib/inertia_rails/renderer.rb

@@ -41,7 +41,7 @@ def render
       end
       if @request.headers['X-Inertia']
         @response.set_header('X-Inertia', 'true')
-        @render_method.call json: page, status: @response.status, content_type: Mime[:json]
+        @render_method.call json: page.to_json, status: @response.status, content_type: Mime[:json]
       else
         return render_ssr if configuration.ssr_enabled rescue nil
         @render_method.call template: 'inertia', layout: layout, locals: view_data.merge(page: page)