51 replies

Statefulness and data sharing for Pieces

Hi,
let's imagine the following: you want to keep track of some data about the people who join and leave a certain voice channel. It would be convenient to store this data alongside the listener and maybe provide an interface to it directly from the listener.
However, it's not fully clear how and when Pieces are instantiated. There are no examples of holding (let alone sharing) any state. How to do this right?
1. is it okay to hold state in a Listener instance?
2. if so, how to access the very same instance somewhere else?
3. if not, what to do instead? Exposing all that data via the container sounds quite painful because that's very far from encapsulated. What would you do to expose some data managed by a certain event handler?

Solution

use a database like sqlite, postgres, mongo, etc. Especially if you want to retain it between reboots. Otherwise, remember how DJS and sapphire do caching internally:

// store.ts
import { Collection } from 'discord.js';
import { container } from '@sapphire/framework';

export const myCache = new Collection<KeyType, ValueType>();
container.myCache = myCache;

declare module '@sapphire/framework' {
  interface Container {
    myCache: typeof myCache;
  }
}

// listener
this.container.myCache.get('id');
this.container.myCache.set('id', value);
// etc

// store.ts
import { Collection } from 'discord.js';
import { container } from '@sapphire/framework';

export const myCache = new Collection<KeyType, ValueType>();
container.myCache = myCache;

declare module '@sapphire/framework' {
  interface Container {
    myCache: typeof myCache;
  }
}

// listener
this.container.myCache.get('id');
this.container.myCache.set('id', value);
// etc

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Statefulness and data sharing for Pieces

Solution

use a database like sqlite, postgres, mongo, etc. Especially if you want to retain it between reboots. Otherwise, remember how DJS and sapphire do caching internally:

// store.ts
import { Collection } from 'discord.js';
import { container } from '@sapphire/framework';

export const myCache = new Collection<KeyType, ValueType>();
container.myCache = myCache;

declare module '@sapphire/framework' {
  interface Container {
    myCache: typeof myCache;
  }
}

// listener
this.container.myCache.get('id');
this.container.myCache.set('id', value);
// etc

// store.ts
import { Collection } from 'discord.js';
import { container } from '@sapphire/framework';

export const myCache = new Collection<KeyType, ValueType>();
container.myCache = myCache;

declare module '@sapphire/framework' {
  interface Container {
    myCache: typeof myCache;
  }
}

// listener
this.container.myCache.get('id');
this.container.myCache.set('id', value);
// etc

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Statefulness and data sharing for Pieces

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