# ConsumerEachBatchPayload

**Kind:** Type

**Source:** [`packages/microservices/external/kafka.interface.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/external/kafka.interface.ts#L1023)

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

Type alias to keep compatibility with

`ConsumerEachBatchPayload` is a compatibility type alias for the payload supplied to Kafka consumer `eachBatch` handlers. It provides access to the received batch, message offset controls, heartbeat handling, and consumer lifecycle state when processing Kafka records in batches.

## Definition

```ts
EachBatchPayload
```

## Diagram

```mermaid
graph LR
  Consumer[Kafka Consumer] --> Handler[eachBatch Handler]
  Handler --> Payload[ConsumerEachBatchPayload]
  Payload --> Batch[batch.messages]
  Payload --> Offset[resolveOffset]
  Payload --> Heartbeat[heartbeat]
  Payload --> State[isRunning / isStale]
```

## Usage

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

async function processKafkaBatch({
  batch,
  resolveOffset,
  heartbeat,
  isRunning,
  isStale,
}: ConsumerEachBatchPayload) {
  for (const message of batch.messages) {
    if (!isRunning() || isStale()) {
      break;
    }

    const value = message.value?.toString();
    console.log(`Processing message: ${value}`);

    // Process the message before marking its offset as resolved.
    resolveOffset(message.offset);

    // Keep the Kafka consumer session alive during long-running work.
    await heartbeat();
  }
}
```

## AI Coding Instructions

- Use this type for Kafka `eachBatch` callbacks to preserve compatibility with the underlying Kafka consumer payload.
- Check `isRunning()` and `isStale()` while iterating through large batches to avoid processing invalid or revoked work.
- Call `resolveOffset()` only after a message has been processed successfully.
- Invoke `heartbeat()` during long-running batch processing to prevent consumer session timeouts.
- Treat `batch.messages` as ordered Kafka records and handle message values that may be `null`.