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Configs

Configuration Library

Nova uses SpongePowered/Configurate, but most of the time you'll be dealing with Nova's ConfigProvider, which helps you with config reloading.

Provider

To help with config reloading, Nova offers the Provider class.
ConfigProviders are automatically reloaded when the config is reloaded. You can also chain value modification calls on a Provider. Those modification steps will then be run lazily every time the config is reloaded.

Some of those modification functions are:

  • map - Maps the value to a new value.
  • orElse - Falls back to a default value if the value is null.
  • flatMap - Performs a flatMap operation for a Provider<List<*>>.
  • flatten - Performs a flattening operation for a Provider<List<List<*>>>.
  • requireNonNull - Throws an exception if the value is null.

Every time such a modification function is called, a new Provider is created and returned. This allows you to create several modified versions from the same Provider.

You might also be interested in these Provider-related top-level functions:

  • provider(value: T) - Creates a constant Provider from a given value.
  • provider(loadValue: () -> T) - Creates a Provider with the given value loader.
  • combinedProvider - Creates a Provider<List<T>> from a list of Provider<T>s.

Config extraction

Nova will automatically extract all configs from resources/configs/ on startup. New or changed keys will automatically be added / updated on the server as well, unless they have been modified by an admin.

Accessing configs

To access the configs, retrieve them from Configs.
You can either use their names: 

Configs["example:ruby"] // namespace:name (drop the .yml)

Or retrieve the config of a NovaItem or NovaBlock using NovaItem.config and NovaBlock.config.

All of the above ways will result in you obtaining a ConfigProvider, which is a Provider<CommentedConfigurationNode>. (Note that Configurate does not have support for yaml comments yet, but this should not be an issue unless you need to write to the config file.)
Now, you can either retrieve the raw config node using Provider.get(), or get a reloadable entry provider using ConfigProvider.entry<Type>("path") and ConfigProvider.optionalEntry<Type>("path").

val exampleValue1: Int by Items.EXAMPLE_ITEM.config.entry<Int>("example_value") // (1)!
val exampleValue2: Int? by Items.EXAMPLE_ITEM.config.optionalEntry<Int>("optional_value") // (2)!
  1. Delegating to the Provider<Int> will cause this field automatically change every time the config is reloaded.
  2. Using ConfigProvider#optionalEntry, you can get a Provider<Int?>, where the value is null if the key is not present in the config.