Configuration Loaders

Let’s break down how Configurate works, beginning with the loading process. Configurate provides ConfigurationLoaders for common configuration formats, standing as the manager of the physical configuration file, allowing you to save and load data from the given resource. They also allow you to load empty configurations, giving you the option of hard-coding default values or loading from a pre-written file.

Tip

The default and recommended config format for Sponge plugins is HOCON.

Getting your Loader

Note

The default ConfigurationLoader can be used instead if you’re using only a single HOCON config file; see the main configuration page.

First, let’s grab a new HoconConfigurationLoader that points to our configuration file.

import java.nio.file.Path;
import ninja.leaping.configurate.commented.CommentedConfigurationNode;
import ninja.leaping.configurate.hocon.HoconConfigurationLoader;
import ninja.leaping.configurate.loader.ConfigurationLoader;

Path potentialFile = getConfigPath();
ConfigurationLoader<CommentedConfigurationNode> loader =
        HoconConfigurationLoader.builder().setPath(potentialFile).build();

The loader will also hold a generic type depending what kind of node it will build. These Configuration Nodes will be discussed in a later section.

ConfigurationLoaders usually hold a builder for you to statically access and create a new instance of the loader of your desired type. For a basic configuration, we don’t really need to specify anything other than the file we want to load from and/or save to, so all we’ll do is tell it exactly that, using HoconConfigurationLoader.builder().setPath(path). We then tell the builder to build the instance (build()) for it and store it in a variable.

Of course, this isn’t the only way to load a file. The builder also has the method setURL(url), in case you want to load a resource without using a Path object. Bear in mind that configuration loaders created from a URL are read-only as they have no way of writing back data to the URL.

This functionality may be used to bundle default configurations with your plugin jar file and load them as initial configuration to be edited by the server administrator (or your plugin itself).

Note

This example uses a HoconConfigurationLoader, which is the recommended approach for Sponge plugins, but you can also use a YAMLConfigurationLoader or GsonConfigurationLoader for loading legacy configs.

Loading and Saving

Once you obtained your ConfigurationLoader you can use it to obtain an empty ConfigurationNode using the createEmptyNode() method.

import ninja.leaping.configurate.ConfigurationNode;
import ninja.leaping.configurate.ConfigurationOptions;

Path potentialFile = getConfigPath();
ConfigurationLoader<CommentedConfigurationNode> loader =
        HoconConfigurationLoader.builder().setPath(potentialFile).build();
ConfigurationNode rootNode = loader.createEmptyNode(ConfigurationOptions.defaults());

This method expects the ConfigurationOptions to use as a parameter. Unless you want to use features like custom type serialization, you can just use ConfigurationOptions#defaults() to create an options object with default values.

Using the load() method you can attempt to load the configuration contents from the source specified upon creation of the ConfigurationLoader. It also expects a ConfigurationOptions instance, but also provides a no-args form that is shorthand for load(ConfigurationOptions.defaults()).

import java.io.IOException;

Path potentialFile = getConfigPath();
ConfigurationLoader<CommentedConfigurationNode> loader =
        HoconConfigurationLoader.builder().setPath(potentialFile).build();
ConfigurationNode rootNode;
try {
    rootNode = loader.load();
} catch(IOException e) {
    // handle error
}

If the Path given does not exist, the load() method will create an empty ConfigurationNode. Any other error will lead to an IOException being thrown which you will need to handle properly.

If you have injected the default loader, it’s a good idea to get its ConfigurationOptions, since they contain the ability to serialise and deserialise a large number of Sponge objects.

Once you modified your ConfigurationNode to hold the data you like to be saved, you can use the ConfigurationLoader to save the node to the file specified while creating the loader. If that file does not exist, it will be created. If it does exist, all contents will be overwritten.

try {
    loader.save(rootNode);
} catch(IOException e) {
    // handle error
}

Again, errors will be propagated as an IOException and must be handled.

Tip

We recommend saving the config after loading it (for the first time after an update) to ensure that newly added or migrated configuration options are written to disk. If you need to save the config afterwards it is strongly recommended to do this outside of the main thread. See also common Bad Practices you should avoid.

Loading a Default Config from the Plugin Jar File

A popular way to provide a default configuration file with your plugin is to include a copy of it in your plugin jar, copying it to the config directory when the config file has yet to be created. You can use the Asset API to do this, as shown in the example below:

PluginContainer plugin = ...;
Path path = ...;

Sponge.getAssetManager().getAsset(plugin, "default.conf").get().copyToFile(path, false, true);
loader = HoconConfigurationLoader.builder().setPath(path).build();
rootNode = loader.load();

For this example it is important to note that the AssetManager#getAsset(String) method works relative to the plugin’s asset folder. So, if in the above example the plugin ID is myplugin, the default.conf file must not lie in the jar file root, but instead in the directory assets/myplugin. This example also uses Asset#copyToFile(Path, boolean, boolean) which allows the file creation to override existing files only if specified.

Note

If the config file cannot be found inside your plugin jar, then you will get a NoSuchElementException from the Optional<Asset>.get() method. Please make sure that you configure your build system to include it in the jar.

If you have an extra configuration class, you can use a much easier approach that also works if the only a part of your config is missing. See also the examples on the Serializing Objects page.

Updating Configuration Files from the Default Configuration

If you would like to merge new nodes and their values to your existing configuration file you can use your CommentedConfigurationNode and load values from a given asset explained above. This will take each node in your asset file and attempt to place it into the new root node if it does not exist. This method is different to simply copying to a file as this will automatically place values that were absent while just copying to file will not.

PluginContainer plugin = ...;

node.mergeValuesFrom(HoconConfigurationLoader.builder()
                    .setURL(plugin.getAsset("default.conf").get().getUrl())
                    .build()
                    .load(ConfigurationOptions.defaults()));

Note

This will not change the values of preexisting configuration nodes if they are already present, so this method can be called regardless of whether or not the server already has a previous version of your configuration.