Checking Configuration File Versions

Often, you'll want to check the user's current version of your app against the last version that required some sort of configuration change; moreover, you'll want to run some "re-configuration" steps if the user's version is older than the last version that required a configuration update.

The Configurator allows for this via its compare_version method.

Assume you have a config file that looks like this:

---
app_data:
  # The current version of the app
  APP_VERSION: 0.8.8

  # ...other keys...

...and that, somewhere in your app, you store a constant that contains the config version that requires a re-configuration:

LATEST_CONFIG_VERSION = 0.9.5

...this will initiate a version check (and give you the option to do something with that information):

# Store the current version of your app in a
# property of the Configurator.
configuration.current_version = configuration.app_data['APP_VERSION']

# Store the last version of your app that required
# a re-configuration in a property of the Configurator.
configuration.last_version = LATEST_CONFIG_VERSION

# Run the check. If the current version is older than
# the "last" version, use a block to tell the Configurator
# what to do.
configuration.compare_version do |c, l|
  puts "We need to update from #{c} to #{l}..."
  # ...do stuff...
end

Two items to note:

1. If the current_version parameter is nil, the Configurator will assume that it the app needs to be updated when compare_version is run.
2. If the current version is later than the last version that required re-configuration, the whole block is skipped over (allowing your app to get on with its day).