---
title: WORKFLOW_SERIALIZE
---

# WORKFLOW_SERIALIZE



A symbol used to define custom serialization for user-defined class instances. The static method should accept an instance and return serializable data.

## Usage

{/* @expect-error:2351 */}

```typescript lineNumbers
import { WORKFLOW_SERIALIZE, WORKFLOW_DESERIALIZE } from "@workflow/serde";

class Point {
  constructor(public x: number, public y: number) {}

  static [WORKFLOW_SERIALIZE](instance: Point) {
    return { x: instance.x, y: instance.y };
  }

  static [WORKFLOW_DESERIALIZE](data: { x: number; y: number }) {
    return new Point(data.x, data.y);
  }
}
```

## API Signature

{/* @skip-typecheck */}

```typescript
static [WORKFLOW_SERIALIZE](instance: T): SerializableData
```

### Parameters

<TSDoc
  definition={`
interface Parameters {
/**
 * The class instance to serialize.
 */
instance: T;
}
export default Parameters;`}
/>

### Returns

The method should return serializable data. This can be:

* Primitives (`string`, `number`, `boolean`, `null`, `undefined`, `bigint`)
* Plain objects with serializable values
* Arrays of serializable values
* Built-in serializable types (`Date`, `Map`, `Set`, `RegExp`, `URL`, etc.)
* Other custom classes that implement serialization

## Requirements

<Callout type="warn">
  The method must be implemented as a **static** method on the class. Instance methods are not supported.
</Callout>

* Both `WORKFLOW_SERIALIZE` and `WORKFLOW_DESERIALIZE` must be implemented together
* The returned data must itself be serializable
* The SWC compiler plugin automatically detects and registers classes that implement these symbols

<Callout type="warn">
  This method runs inside the workflow context and is subject to the same constraints as `"use workflow"` functions:

  * No Node.js-specific APIs (like `fs`, `path`, `crypto`, etc.)
  * No non-deterministic operations (like `Math.random()` or `Date.now()`)
  * No external network calls

  Keep this method simple and focused on extracting data from the instance.
</Callout>


## Sitemap
[Overview of all docs pages](/sitemap.md)