Application Commands
Application commands are Discord’s newest way of interacting with bots in Discord, replacing the traditional method of parsing out message content.
It’s possible to interface with application commands using Gateway listener methods, but the quarkus-discord4j-commands extension comes with some additional goodies that make it easy to develop application commands.
Installation
Add the quarkus-discord4j-commands artifact to your Quarkus app:
<dependency>
<groupId>io.quarkiverse.discord4j</groupId>
<artifactId>quarkus-discord4j-commands</artifactId>
<version>0.0.1</version>
</dependency>Creating commands
Before you can start listening for commands in code, you first need to define your application commands and register them in Discord so they can be used. The easiest way to do this is by defining your commands using JSON. Quarkus Discord Bot will automatically serialize and register the JSON files found in META-INF/commands and subdirectories as application commands (when configured to do so).
| Discord supports two types of application commands: global commands and guild commands. Global commands take an hour to propagate after being registered, so it’s recommended to register your commands as guild commands while you’re developing. |
Let’s create a guild command by creating the following JSON file in META-INF/commands/test:
{
"name": "foo"
"description": "Foo command"
"options": [
{
"type": 3,
"name": "name",
"description": "The text to reply to the command with"
}
]
}You can find the full JSON schema of application commands here.
Now that you’ve created a guild command using JSON, you need to configure the ID of the guild command, and configure your Quarkus Discord Bot to register the command when your app starts. You can do that by configuring the following properties:
quarkus.discord4j.guild-commands.test.overwrite-on-start=true
quarkus.discord4j.guild-commands.test.guild-id=<test guild ID>The configuration name of the guild commands, test, must match the name of the subdirectory in META-INF/commands we created earlier.
To obtain the ID of your test guild, turn on developer mode in your Discord client by going to User Settings > App Settings > Advanced and checking the Developer Mode option. Then, right click your server’s icon and click Copy ID.
|
You can find the full list of configurable properties in the Reference.
Listening and responding to commands
To listen for the command you just defined, create the following class:
class FooCommand {
@Command(value="foo", guild="test") (1)
Mono<Void> onFoo(ChatInputInteractionEvent event) { (2)
String name = event.getOption("name")
.flatMap(ApplicationCommandInteractionOption::getValue)
.map(ApplicationCommandInteractionOptionValue::asString)
.get(); (3)
return event.reply(name); (4)
}
}| 1 | The guild value indicates that we’re listening to a guild command from the guild ID we configured under the name test. Simply omit the guild value if you want to listen for global commands. |
| 2 | Like Gateway listener methods, command methods can return Mono, Uni, Flux, or Multi. |
| 3 | Here, we extract the value of the name option passed to our foo command. |
| 4 | When we receive a command, we have to acknowledge it. Here, we acknowledge the command by immediately replying. |
| It is planned to allow option values to be injected directly into command methods in the future. |
Subcommands and subcommand groups
You can listen for subcommands and subcommand groups using a slightly different class hierarchy. Let’s imagine the command we defined earlier includes subcommands and subcommand groups, and create the following class for it:
@Command(value="foo", guild="test")
class FooCommands {
@SubCommand("baz") (1)
Mono<Void> onBaz(ChatInputInteractionEvent event) {
// acknowledge command
}
@SubCommandGroup("bar")
class BarCommands {
@SubCommand("baz") (2)
Mono<Void> onBaz(ChatInputInteractionEvent event) {
// acknowledge command
}
}
}| 1 | We listen for /foo baz commands |
| 2 | We listen for /foo bar baz commands |