# ConsumerEachMessagePayload

**Kind:** Type

**Source:** [`packages/microservices/external/kafka.interface.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/external/kafka.interface.ts#L1017)

**Part of:** [Microservices](subsystem-packages-microservices)

Type alias to keep compatibility with

`ConsumerEachMessagePayload` is a compatibility type alias for the payload passed to a Kafka consumer's `eachMessage` handler. It provides typed access to the consumed topic, partition, message, heartbeat function, and partition-pausing controls while preserving compatibility with KafkaJS consumer APIs.

## Definition

```ts
EachMessagePayload
```

## Diagram

```mermaid
graph LR
  A[Kafka Consumer] --> B[eachMessage Handler]
  B --> C[ConsumerEachMessagePayload]
  C --> D[topic]
  C --> E[partition]
  C --> F[message]
  C --> G[heartbeat]
  C --> H[pause]
```

## Usage

```ts
import { ConsumerEachMessagePayload } from '@nestjs/microservices';

async function handleKafkaMessage(
  payload: ConsumerEachMessagePayload,
): Promise<void> {
  const { topic, partition, message, heartbeat } = payload;

  const value = message.value?.toString();

  console.log({
    topic,
    partition,
    offset: message.offset,
    value,
  });

  // Call during long-running message processing to keep the consumer alive.
  await heartbeat();
}
```

## AI Coding Instructions

- Use `ConsumerEachMessagePayload` when typing handlers that receive KafkaJS `eachMessage` callback data.
- Treat `message.value` as nullable; check for `null` or use optional chaining before decoding it.
- Preserve access to `heartbeat()` in long-running handlers to avoid consumer session timeouts.
- Use the provided `topic`, `partition`, and `message.offset` values for logging, tracing, and idempotency handling.
- Keep this alias in place for KafkaJS compatibility instead of replacing it with a manually recreated payload shape.