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# Hook Data Type Reference

> Technical reference for the BAML React hook data type

The `HookData` type represents the non-null data from a BAML React hook. This type is useful when you know the data exists and want to avoid undefined checks.

**`Example Usage`**

```typescript title="Example Usage"
function Component() {
  const hook = useTestAws({
    stream: true, // optional, defaults to true
  })

  const data = hook.data;

  return (
    <div>
      {data} {/* No need for null checks */}
    </div>
  )
}
```

**`Example Types`**

```typescript title="Example Types"
// Streaming configuration
const streamingData: HookData<'TestAws', { stream: true }> = "Streaming response..."

// Non-streaming configuration
const nonStreamingData: HookData<'TestAws', { stream: false }> = "Final response"
```

**`Type Definition`**

```typescript title="Type Definition"
type HookData<FunctionName extends FunctionNames, Options extends { stream?: boolean } = { stream?: true }> = NonNullable<HookOutput<FunctionName, Options>['data']>
```

## Type Parameters

**`FunctionName`** `generic`

The name of the BAML function being called. Used to infer input and output types.

---

**`Options`** `{ stream?: boolean }`

Configuration object that determines streaming behavior. Defaults to `{ stream?: true }`.

---

## Type Details

**`type`** `NonNullable<HookOutput<FunctionName, Options>['data']>`

A utility type that removes undefined from the data property of HookOutput. This means the type will be either FinalDataType or StreamDataType depending on the streaming configuration.

---

> Technical reference for the BAML React hook data type