Functions

The CommandAPI has support to use Minecraft's functions within your plugins. This is handled by using a class provided by the CommandAPI called FunctionWrapper, which allows you to execute functions. The CommandAPI also provides support to let you run your own commands within Minecraft function files.

Functions in 1.16+

Developer's Note:

Minecraft 1.16+ change the way that datapacks are loaded on the server, so that they load before plugins are enabled. This means that non-vanilla commands that are declared in functions and tags will be detected as invalid, causing the server to throw a lot of errors at the very start.

The CommandAPI reloads datapacks once the server has finished loading using all declared commands, therefore the error messages at the start of the server can be ignored.

Using custom commands in functions

In order to use a command from your plugin in a .mcfunction file, you must register your command in your plugin's onLoad() method, instead of the onEnable() method. Failure to do so will not allow the command to be registered for Minecraft functions, causing the function file to fail to load during the server startup phase.

Developer's Note:

In short, if you want to register a command which can be used in Minecraft functions, register it in your plugin's onLoad() method.

public class Main extends JavaPlugin {

    @Override
    public void onLoad() {
        // Commands which will be used in Minecraft functions are registered here

        new CommandAPICommand("killall")
            .executes((sender, args) -> {
                // Kills all enemies in all worlds
                Bukkit.getWorlds().forEach(w -> w.getLivingEntities().forEach(e -> e.setHealth(0)));
            })
            .register();
    }
    
    @Override
    public void onEnable() {
        // Register all other commands here
    } 
}

class Main : JavaPlugin() {

    override fun onLoad() {
        // Commands which will be used in Minecraft functions are registered here

        CommandAPICommand("killall")
            .executes(CommandExecutor { _, _ ->
                // Kills all enemies in all worlds
                Bukkit.getWorlds().forEach { world -> world.livingEntities.forEach { entity -> entity.health = 0.0 } }
            })
            .register()
    }

    override fun onEnable() {
        // Register all other commands here
    }

}