Buffer support for ioredis and node-redis

This allows subscribing to binary data payloads

Author: skabbes

README.md

@@ -133,6 +133,28 @@ const pubsub = new RedisPubSub({
 });
 ```
 
+**Receiving messages as Buffers**
+
+Some Redis use cases require receiving binary-safe data back from redis (in a Buffer). To accomplish this, override the event names for receiving messages and pmessages.  Different redis clients use different names, for example:
+
+| library | message event | message event (Buffer) | pmessage event | pmessage event (Buffer) |
+| ------- | ------------- | ---------------------- | -------------- | ----------------------- |
+| ioredis | `message` | `messageBuffer` | `pmessage` | `pmessageBuffer` |
+| node-redis | `message` | `message_buffer` | `pmessage` | `pmessage_buffer` |
+
+```javascript
+import { RedisPubSub } from 'graphql-redis-subscriptions';
+import * as Redis from 'ioredis';
+
+const pubsub = new RedisPubSub({
+  ...,
+  // Tells RedisPubSub to register callbacks on the messageBuffer and pmessageBuffer EventEmitters
+  messageEventName: 'messageBuffer',
+  pmessageEventName: 'pmessageBuffer',
+});
+```
+
+
 **Also works with your Redis Cluster**
 
 ```javascript

src/redis-pubsub.ts

@@ -14,6 +14,8 @@ export interface PubSubRedisOptions {
   reviver?: Reviver;
   serializer?: Serializer;
   deserializer?: Deserializer;
+  messageEventName?: string;
+  pmessageEventName?: string;
 }
 
 export class RedisPubSub implements PubSubEngine {
@@ -28,6 +30,8 @@ export class RedisPubSub implements PubSubEngine {
       reviver,
       serializer,
       deserializer,
+      messageEventName = 'message',
+      pmessageEventName = 'pmessage',
     } = options;
 
     this.triggerTransform = triggerTransform || (trigger => trigger as string);
@@ -69,9 +73,9 @@ export class RedisPubSub implements PubSubEngine {
     }
 
     // handle messages received via psubscribe and subscribe
-    this.redisSubscriber.on('pmessage', this.onMessage.bind(this));
+    this.redisSubscriber.on(pmessageEventName, this.onMessage.bind(this));
     // partially applied function passes undefined for pattern arg since 'message' event won't provide it:
-    this.redisSubscriber.on('message', this.onMessage.bind(this, undefined));
+    this.redisSubscriber.on(messageEventName, this.onMessage.bind(this, undefined));
 
     this.subscriptionMap = {};
     this.subsRefsMap = {};
@@ -194,4 +198,4 @@ export type TriggerTransform = (
 ) => string;
 export type Reviver = (key: any, value: any) => any;
 export type Serializer = (source: any) => string;
-export type Deserializer = (source: string) => any;
+export type Deserializer = (source: string | Buffer) => any;