website/docs/guide/walkthrough/plugins.md

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Plugins

:::tip TLDR: Plugins help reduce code repetition and are installable via sern plugins. Put them onto the plugins field of a command/event module. :::

Installing

Chances are, you just want your bot to work. Plugins can preprocess and create reusable conditions for modules.

run:

sern plugins

• Install your favorite(s) (or the ones that look the coolest). In my imaginary mind, I installed the ownerOnly plugin.
  • This should install in plugins directory in src.
• Some plugins only work with specific types. Most are targeted towards slash / both modules.
• Add to your module.

import { commandModule, CommandType } from '@sern/handler'
import { ownerOnly } from '../plugins'

export default commandModule({ 
    type: CommandType.Both,
    plugins: [ownerOnly(['182326315813306368')],
    description: 'ping command',
    execute: (ctx) => {
        ctx.reply('hello, owner');
    }
})

┗|｀O′|┛ perfect, your first plugin!

Creating your own plugins

The controller determines in plugins whether to continue or fail.

The controller object

export interface Controller {
  next: () => Ok<void>;
  stop: () => Err<void>;
}

Init Plugins

Init plugins modify how commands are loaded or do preprocessing. An instance of the above object is passed into every plugin.
This controls whether a module is stored into sern.

import { CommandInitPlugin } from '@sern/handler'
import path from 'path'
export const inDir = (dir: string) => {
    return CommandInitPlugin(({ module, absPath }) => {
       if(path.dirname(absPath) !== dir) {
          console.log(+new Date(),  `${module.name} is not in the correct directory!`);
          return controller.stop()
       }
       console.log(+new Date(),  `${module.name} is in the correct directory!`);
       return controller.next(); //continue
    });
}

Above, this simple plugin logs that the module has been loaded along with a timestamp.

Event Plugins

• An event is emitted by discord.js.
• This event is passed to all plugins (in order!!),
• If all are successful,

The command is executed. Calling controller.stop() notifies sern that this command should not be run, and command is ignored.

Can you predict the behavior of this command?

• Before loading into sern, this command module will check if this module is in the correct directory other.
• Before an event occurs, this command module will check if the user has the id 182326315813306368.

:::tip Event Plugins are good for filtering, preconditions, parsing. :::

If all plugins return controller.next(), this command replies Pong 🏓