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https://github.com/fredericbarthelet/typebridge

Typescript toolbox for AWS EventBridge
https://github.com/fredericbarthelet/typebridge

aws eventbridge hacktoberfest serverless typescript

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Typescript toolbox for AWS EventBridge

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# TypeBridge

Typescript toolbox for AWS EventBridge

## Advantages

- Programmatical definition of your application events
- Typed publish and consume APIs
- Automatically batches `putEvents` call when publishing more than 10 events at a time
- Check for event payload size before publishing

## Quick install

### Add typebridge dependency

`npm i typebridge --save`

> Typebridge `v1` and above is meant to be used with [AWS SDK v3](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-eventbridge/index.html). If you want to use Typebridge with AWS SDK v2, you should install `v0` versions of this package `npm i typebridge@^0`

### Define your bus and events

```ts
import { EventBridgeClient } from '@aws-sdk/client-eventbridge';
import { Bus, Event } from 'typebridge';

export const MyBus = new Bus({
name: 'applicationBus',
EventBridge: new EventBridgeClient({}),
});

export const MyEventPayloadSchema = {
type: 'object',
properties: {
stringAttribute: { type: 'string' },
numberAttribute: { type: 'integer' },
},
required: ['stringAttribute'],
additionalProperties: false
} as const;

export const MyEvent = new Event({
name: 'MyEvent',
bus: MyBus,
schema: MyEventPayloadSchema,
source: 'mySource'
});
```

### Use the Event class to publish

```ts
import { MyEvent } from './events.ts';

export const handler = async (event) => {
await MyEvent.publish({
stringAttribute: 'string',
numberAttribute: 12,
})

return 'Event published !'
};
```

Typechecking is automatically enabled:

```ts
await MyEvent.publish({
stringAttribute: 'string',
numberAttribute: 12,
// the following line will trigger a Typescript error
anotherAttribute: 'wrong'
})
```
### Use the Event class to create an event

```ts
import { MyBus, MyEvent } from './events.ts';

export const handler = async (event) => {
const events = event.details.map(detail => MyEvent.create({
stringAttribute: detail.stringAttribute,
numberAttribute: detail.numberAttribute,
})
await MyBus.put(events);

return 'Event published !'
};
```

### Use the Event class to generate trigger rules

Using the serverless framework with `serverless.ts` service file:

```ts
import type { Serverless } from 'serverless/aws';

const serverlessConfiguration: Serverless = {
service: 'typebridge-test',
provider: {
name: 'aws',
runtime: 'nodejs12.x',
},
functions: {
hello: {
handler: 'MyEventHandler.handler',
events: [
{
eventBridge: {
eventBus: 'applicationBus',
pattern: NewUserConnectedEvent.pattern,
},
},
],
}
}
}

module.exports = serverlessConfiguration;
```

### Use the Event class to type input event

```ts
import { PublishedEvent } from 'typebridge';
import { MyEvent } from './events.ts';

export const handler = (event: PublishedEvent) => {
// Typed as string
return event.detail.stringAttribute;
}
```

### Use the Event class to validate the input event

Using [middy](https://github.com/middyjs/middy) middleware stack in your lambda's handler, you can throw an error before your handler's code being executed if the input event `source` or `detail-type` were not expected, or if the `detail` property does not satisfy the JSON-schema used in `MyEvent` constructor.

```ts
import middy from '@middy/core';
import jsonValidator from '@middy/validator';
import { MyEvent } from './events.ts';

const handler = (event) => {
return 'Validation succeeded';
};

// If event.detail does not match the JSON-schema supplied to MyEvent constructor, the middleware will throw an error
export const main = middy(handler).use(
jsonValidator({ inputSchema: MyEvent.publishedEventSchema }),
);
```