NestJS Type Safe Event Emitter Module
Type Safe, contract-driven event emitter module for a NestJS application.
Uses [zod](https://github.com/colinhacks/zod) object defintions to create typesafe event listeners and emitter, with automatic validation of args.
## Features
- End-to-end type safe wrapper for `eventemitter2`
- Wild card events
- Enforce events have a listener via `contract.required(, )`
- Optional event listeners via `contract.optional(, )`
## Installation
```bash
npm i eventemitter2 nestjs-typed-events
```
## Limitations
- You can have multiple event listeners on one class **only** if the events have the same args signature.
## Example
1. Register in `app.module`
```typescript
import { EventContractBuilder, EventEmitterModule } from 'nestjs-typed-events';
const contract = EventContractBuilder.create()
.required(
'test.event',
z.object({
foo: z.string(),
}),
)
.optional('optional.event', z.string())
.build();
@Module({
imports: [
EventEmitterModule.forRoot(EventEmitterModule, {
contract,
}),
],
})
export class AppModule {}
```
2. Register your event listener
```typescript
import { Injectable } from '@nestjs/common';
import {
EventListenerDecoratorFactory,
ContractEvent,
} from 'nestjs-typed-events';
const ContractEvent = EventListenerDecoratorFactory(contract);
@Injectable()
@ContractEvent('test.event')
export class TestWatcher {
async handle(args: ContractEvent) {}
}
```
3. Profit
