# IdentitySerializer

**Kind:** Class

**Source:** [`packages/microservices/serializers/identity.serializer.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/serializers/identity.serializer.ts#L3)

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

`IdentitySerializer` is a microservices serializer that returns values without transforming their content. It is useful when messages are already in the required transport format or when a custom serialization step is unnecessary. Its `serialize()` method preserves the original payload for downstream transport handling.

**Implements:** `Serializer`

## Methods

| Method | Signature | Returns |
|---|---|---|
| `serialize` | `serialize(value: any)` | `void` |

## Diagram

```mermaid
graph LR
  A[Application Payload] --> B[IdentitySerializer]
  B -->|serialize() returns unchanged value| C[Microservice Transport]
```

## Usage

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

const serializer = new IdentitySerializer();

const payload = {
  event: 'user.created',
  userId: 'user_123',
};

const serializedPayload = serializer.serialize(payload);

console.log(serializedPayload);
// { event: 'user.created', userId: 'user_123' }
```

## AI Coding Instructions

- Use `IdentitySerializer` when the transport or application already accepts the payload in its original form.
- Do not expect `serialize()` to convert objects into JSON, buffers, or another wire format.
- Configure this serializer in microservice client or server transport options when no custom serialization is required.
- Prefer a custom serializer when the target transport requires encoding, schema mapping, validation, or payload normalization.