Permissions

This tutorial shows how to handle and check permissions.

Setup

You will need to have set up the Fabric Permissions API in your environment. See the libraries page

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Command Permissions

Here is our command without a permission check:

public class MyCommandsMod implements DedicatedServerModInitializer {
    @Override
    public void onInitializeServer() {
        CommandRegistrationCallback.EVENT.register(dispatcher, dedicated -> {
            dispatcher.register(
                    literal("mymodcommand")
                            .then(literal("subcommand")
                                    .executes(ctx -> {
                                        ctx.getSource().getPlayer().sendMessage(new LiteralText("It works"), false);
                                        return 1;
                                    })
                            )
            );
        });
    }
}

This allows any player on the server to use /mymodcommand. But in many cases, we want to restrict who can run the command

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Permission Levels

Every player has a permission level. Here is a non-extensive list of standard values:

• Standard player: 0
• Command blocks: 2
• Operator: Specified in server.properties, default 4

What do the levels allow?

• 0: Normal non-operator commands
• 1: Bypass spawn protection
• 2: Operator commands without moderation perms
• 3: Moderation commands
• 4: /stop command

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Set a Command's Permission Level

public class MyCommandsMod implements DedicatedServerModInitializer {
    @Override
    public void onInitializeServer() {
        CommandRegistrationCallback.EVENT.register(dispatcher, dedicated -> {
            dispatcher.register(
                    literal("mymodcommand")
                            .then(literal("subcommand")
                                    .requires(scs -> scs.hasPermissionLevel(3))
                                    .executes(ctx -> {
                                        ctx.getSource().getPlayer().sendMessage(new LiteralText("It works"), false);
                                        return 1;
                                    })
                            )
            );
        });
    }
}

.requires(scs -> scs.hasPermissionLevel(3))

This line means that only players with permission level 3 or greater can run the following parts of the tree

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Permission Nodes

While the permission level system provides security, it does not provide flexibility for servers. For this reason, we use the Fabric Permissions API. It allows you to declare multiple permission nodes for your mod, and them to be used by any permission manager mod that supports it such as LuckPerms or PlayerRoles.

Instead of .requires(scs -> scs.hasPermissionLevel(3)), we can do .requires(Permissions.require("mymod.command.mymodcommand.subcommand", 3))

This line requires that the player have permission level 3 or the permission node of the name mymod.command.mymodcommand.subcommand

Checking permission nodes outside of commands

public class PermissionUtils {
    public boolean hasPermissionOrNode(ServerPlayerEntity player, int i, String node) {
        return Permissions.check(player, node, i);
    }
}

This code sample will return whether the player has a permission node or has permission level i

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You have now added permissions checks to your code! For more information, read the usage page on Fabric Permission API.