---
url: https://node-ts.github.io/bus/api/bus-core/type-aliases/OnWhenHandler.md
---
[API reference](../../index.md) / [@node-ts/bus-core](../index.md) / OnWhenHandler

# Type Alias: OnWhenHandler

```ts
type OnWhenHandler = object;
```

Defined in: [packages/bus-core/src/workflow/workflow.ts:147](https://github.com/node-ts/bus/blob/2e6cf65c27833b707ae31ee623cfb6343770f434/packages/bus-core/src/workflow/workflow.ts#L147)

A `when` handler of a class workflow, as the mapper stores it

## Properties

### customLookup

```ts
customLookup: 
  | MessageWorkflowMapping
  | undefined;
```

Defined in: [packages/bus-core/src/workflow/workflow.ts:150](https://github.com/node-ts/bus/blob/2e6cf65c27833b707ae31ee623cfb6343770f434/packages/bus-core/src/workflow/workflow.ts#L150)

***

### workflowCtor

```ts
workflowCtor: ClassConstructor<Workflow<WorkflowState>>;
```

Defined in: [packages/bus-core/src/workflow/workflow.ts:148](https://github.com/node-ts/bus/blob/2e6cf65c27833b707ae31ee623cfb6343770f434/packages/bus-core/src/workflow/workflow.ts#L148)

***

### workflowHandler

```ts
workflowHandler: string;
```

Defined in: [packages/bus-core/src/workflow/workflow.ts:149](https://github.com/node-ts/bus/blob/2e6cf65c27833b707ae31ee623cfb6343770f434/packages/bus-core/src/workflow/workflow.ts#L149)