Configuring CORS headers

Depending on how you've setup your app, you may encounter a CORS error. It will look like this in your browser console:

In this case, you need to configure the right CORS headers to allow the domain app.forestadmin.com to trigger an API call on your Application URL, which is a different domain name (e.g. localhost:3000 on development).

Rails
Rails

We use the Rack CORS Gem for this purpose.

gemfile
# Gemfile
source 'https://rubygems.org'
# ...
gem 'forest_liana'
gem 'rack-cors'
congif/application.rb
module YourApp
class Application < Rails::Application
# ...
# For Rails 5, use the class Rack::Cors. For Rails 4, you MUST use the string 'Rack::Cors'.
null_regex = Regexp.new(/\Anull\z/)
config.middleware.insert_before 0, Rack::Cors do
allow do
hostnames = [null_regex, 'localhost:4200', 'app.forestadmin.com', 'localhost:3001']
hostnames += ENV['CORS_ORIGINS'].split(',') if ENV['CORS_ORIGINS']
origins hostnames
resource '*',
headers: :any,
methods: :any,
expose: ['Content-Disposition'],
credentials: true
end
end
end
end