RmqRecordSerializer

Kind: Class

Source: packages/microservices/serializers/rmq-record.serializer.ts

Part of: Microservices

RmqRecordSerializer converts outgoing NestJS microservice packets into RabbitMQ-compatible record payloads. It preserves the request packet shape while extracting or merging RabbitMQ-specific metadata, such as headers and message properties, for transport delivery.

Implements: Serializer

Methods

Diagram

mermaid
graph LR
  A[Application Message] --> B[RmqRecordSerializer]
  B --> C[ReadPacket]
  B --> D[Partial RmqRecord]
  C --> E[RabbitMQ Transport]
  D --> E

Usage

ts
import { RmqRecordSerializer } from '@nestjs/microservices';

const serializer = new RmqRecordSerializer();

const packet = serializer.serialize({
  pattern: 'orders.created',
  data: {
    orderId: 'order_123',
    customerId: 'customer_456',
  },
});

client.send('orders.created', packet.data);

AI Coding Instructions

• Use RmqRecordSerializer at the RabbitMQ transport boundary when outgoing packets may include RabbitMQ record metadata.
• Preserve the standard NestJS ReadPacket fields, especially pattern and data, when extending serialization behavior.
• Ensure RabbitMQ-specific options, such as headers or properties, are carried through without mutating the original payload.
• Keep custom serializers compatible with the serialize(): ReadPacket & Partial<RmqRecord> return contract.
• Test serialization with both plain message payloads and RmqRecord-style payloads containing transport metadata.

How it works

• RmqRecordSerializer is an exported serializer class implementing Serializer<ReadPacket, ReadPacket & Partial<RmqRecord>>. Its serialize method accepts a packet with pattern and data fields. rmq-record.serializer.ts:6-10 packet.interface.ts:5-8 serializer.interface.ts:10-12

• It recognizes a packet only when packet.data is truthy, is a non-null JavaScript object, and is an actual RmqRecord instance according to instanceof. rmq-record.serializer.ts:11-15 isObject checks non-null values whose typeof is object.

• For such a packet, serialize returns a new packet object: it copies the packet’s existing enumerable properties, replaces data with RmqRecord.data, and writes RmqRecord.options to a top-level options field. rmq-record.serializer.ts:16-21 RmqRecord stores its payload in readonly data and can store optional options. rmq.record-builder.ts:25-29

• If the payload does not meet that runtime check—including plain objects that merely resemble a record—the method returns the original packet reference unchanged. rmq-record.serializer.ts:22-23 The serializer test checks reference identity for a non-RmqRecord payload. rmq-record.serializer.spec.ts:31-37

• The method has no explicit error handling or thrown validation error in its implementation. rmq-record.serializer.ts:10-24 It does not modify the input itself when it unwraps an RmqRecord; that branch constructs and returns an object literal. rmq-record.serializer.ts:16-21

• ClientRMQ and ServerRMQ select this class as their serializer when transport options do not specify a custom serializer. client-rmq.ts:488-490 server-rmq.ts:424-426

• In the RMQ client send and event paths, the serialized packet’s top-level options is read and then deleted before the remaining packet is JSON-encoded; those options are spread into RabbitMQ send options, with headers merged separately. client-rmq.ts:393-412 client-rmq.ts:446-484 Therefore, when this serializer returns the input unchanged, that later deletion operates on the caller’s packet object. rmq-record.serializer.ts:22-23 client-rmq.ts:447-451

Relationships

• IMPORTS → isObject