workflow/docs/v4/api-reference/workflow-observability/hydrate-resource-io.mdx

Workflow SDK - Build durable, resilient, and observable workflows

---
title: hydrateResourceIO
description: Hydrate the serialized data fields of a run, step, hook, or event for display.
type: reference
summary: Use hydrateResourceIO with observabilityRevivers to deserialize step input/output for display in observability tools.
prerequisites:
  - /docs/api-reference/workflow-runtime/get-world
related:
  - /docs/api-reference/workflow-observability/observability-revivers
  - /docs/api-reference/workflow-runtime/world/storage
---

Hydrates (deserializes) the data fields of a resource returned by the [World SDK](/docs/api-reference/workflow-runtime/world) — a workflow run, step, hook, or event. Workflow data is serialized using the [devalue](https://github.com/Rich-Harris/devalue) format, so this is required before displaying step input/output in a UI.

The function dispatches on the resource shape: steps get `input`/`output` hydrated, hooks get `metadata`, events get `eventData`, and runs get `input`/`output`.

```typescript lineNumbers
import { getWorld } from "workflow/runtime";
import { hydrateResourceIO, observabilityRevivers } from "workflow/observability"; // [!code highlight]
declare const runId: string; // @setup
declare const stepId: string; // @setup

const world = await getWorld();
const step = await world.steps.get(runId, stepId);
const hydrated = hydrateResourceIO(step, observabilityRevivers); // [!code highlight]
console.log(hydrated.input, hydrated.output);
```

## API Signature

### Parameters

| Parameter | Type | Description |
|-----------|------|-------------|
| `resource` | `WorkflowRun \| Step \| Hook \| Event` | The resource with serialized data fields |
| `revivers` | `Revivers` | Reviver functions for deserialization. Use [`observabilityRevivers`](/docs/api-reference/workflow-observability/observability-revivers) for standard use. |

### Returns

The same resource with its data fields hydrated into plain JavaScript values.

<Callout type="info">
  Encrypted data fields pass through as raw `Uint8Array` values rather than being decrypted — see [Encrypted Data](/docs/api-reference/workflow-observability#encrypted-data).
</Callout>

## Examples

### Display a Run's Steps with Hydrated I/O

```typescript lineNumbers
import { getWorld } from "workflow/runtime";
import { hydrateResourceIO, observabilityRevivers } from "workflow/observability"; // [!code highlight]
declare const runId: string; // @setup

const world = await getWorld();
const steps = await world.steps.list({ runId, resolveData: "all" });

for (const step of steps.data) {
  const hydrated = hydrateResourceIO(step, observabilityRevivers); // [!code highlight]
  console.log(step.stepName, hydrated.input, hydrated.output);
}
```