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Configs

Configuration Library

Nova uses a modified version of 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. This class stores a value of a given type and can be delegated to. Providers have an abstract loadValue function that, depending on its implementation, might load something from a config, a CBF Compound, or anything else.
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 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 - Creates a static Provider from a given value.
  • combinedProvider - Creates a Provider<List<T>> from a list of Provider<T>s.
  • lazyProvider - Creates a Provider whose parent is only created lazily using the given initializer lambda.
  • combinedLazyProvider - Creates a Provider<List<T>> from a list of Provider<T>s, where the Provider<T>s are created lazily using the given initializer lambda.
  • lazyProviderWrapper - Creates a Provider that wraps a lazily initialized static value from given initializer lambda.

Adding configs to your addon

In order to add configs to your addon, create a directory called configs in resources. There, you can add all your .yml configs, which will automatically be extracted 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)

Configs[ResourceLocation("example:ruby")]

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>. Now, you can either retrieve the raw config node using Provider#value, or get a reloadable entry provider using ConfigProvider#entry and ConfigProvider#optionalEntry.

val exampleValue: Int by Configs[Items.RUBY].entry<Int>("example_value") // (1)!
val otherValue: Int? by Configs[Items.RUBY].optionalEntry<Int>("other_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.