Rails render in controller#create is not loading the page - ruby-on-rails

Question

I have a form being submitted by the resident of a condominium to apply a pass for a visitor.
Upon submission I have setup the controller to render a template or redirect it to another path depending on the input of the form and display a flash message on the top of the page after clicking the submit button.
Somehow redirect works fine but render does nothing to the page.
Did try flash.now with render but no flash and it looks like it is not loading anything new on the page.
class VisitorPassesController < ApplicationController
def new
#visitor_pass = VisitorPass.new
#controller = "visitor_passes"
end
def create
unless resident && correct_resident_key?
flash[:danger] = "Invalid resident key."
# render 'new' doesn't work
# render action: 'new' doesn't work
redirect_to new_visitor_pass_path works
redirect_to '/visitor_passes/new' works
return
end
.
.
.
end
end
Here is the output of the console.
Rendering visitor_passes/new.html.erb within layouts/application
Rendered visitor_passes/new.html.erb within layouts/application
Rendered layouts/_rails_default.html.erb
Rendered layouts/_shim.html.erb
Resident Load (0.3ms) SELECT "residents".* FROM "residents" WHERE "residents"."id" = ? LIMIT ? [["id", 155], ["LIMIT", 1]] app/helpers/sessions_helper.rb:17:in 'current_user'
Rendered layouts/_header.html.erb (Duration: 3.1ms | Allocations: 760)
Completed 200 OK in 429ms (Views: 59.6ms | ActiveRecord: 2.3ms | Allocations: 33936)

Answer 1

Flash messages are displayed in the next response cycle (ie after a redirect). If you want to display a flash message in response to the current request use ActionDispatch::Flash::FlashHash#now.
class VisitorPassesController < ApplicationController
def new
#visitor_pass = VisitorPass.new
# just use the controller_name method provided by rails instead
end
def create
# ...
# prefer positive conditions instead of negative
if resident && correct_resident_key?
# do something awesome
else
flash.now[:danger] = "Invalid resident key."
render :new
end
end
end
Also make sure you are using the local: true option on the form if using form_with as it defaults to those pesky XHR remote: true requests.