---
title: "SubFlow"
description: "This page lists the TypeScript SDK names for SubFlows."
canonical_url: "https://docs.superdurable.io/reference/typescript/subflow/"
source: "docs/reference/typescript/subflow.mdx"
locale: "en"
---

# SubFlow

This page lists the TypeScript SDK names for [SubFlows](https://docs.superdurable.io/concepts/primitives/subflow.md).
The doc comment of each API gives its parameters, defaults, and errors. Read
them in the [TypeScript SDK API reference](https://docs.superdurable.io/reference/typescript.md#api-reference).

<a id="api-names"></a>

## API names

| Task                                                 | TypeScript API                                                                | Dex behavior                                                                                             |
| ---------------------------------------------------- | ----------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| Start a child Flow and wait for it                   | **SubFlow\.run** in **waitFor**                                               | [SubFlows](https://docs.superdurable.io/reference/server/runtime-data.md#subflows)                       |
| Set the child timeout, Attributes, and configuration | **SubFlowOptions**                                                            | [SubFlowOptions](https://docs.superdurable.io/reference/server/runtime-data.md#subflow-options)          |
| Choose what happens to an existing child             | **reusePolicy** of **SubFlowOptions**, with **SubFlowReusePolicy**            | [SubFlowReusePolicy](https://docs.superdurable.io/reference/server/runtime-data.md#subflow-reuse-policy) |
| Read the child result                                | **SubFlow\.getConditionResults** in **execute**. It returns a **FlowResult**. | [SubFlow results](https://docs.superdurable.io/reference/typescript/waits.md#subflow-results)            |
| Read the generated child Flow ID                     | **SubFlow\.getFlowId**                                                        | [SubFlowReusePolicy](https://docs.superdurable.io/reference/server/runtime-data.md#subflow-reuse-policy) |
| Stop a child that lost an **AnyOf**                  | **Client.stopFlow** with the child Flow ID                                    | [Stop a Flow](https://docs.superdurable.io/reference/server/runtime-client.md#stop-a-flow)               |

<a id="step-types-that-start-subflows"></a>

## Step types that start SubFlows

Changed in 1.45: a Step whose Step type contains "-" cannot start SubFlows.

The generated child Flow ID joins the parent Flow ID, the Step execution ID,
and the SubFlow index with "-". The Step execution ID itself is the Step type,
"-", and a counter:

```text
SubFlow:{parent Flow ID}-{Step execution ID}-{index}
{Step execution ID} = {Step type}-{n}
```

A dash in the Step type makes the child Flow ID ambiguous. In this example two
parents would share one child:

```text
parent Flow ID "a-b", Step type "C"   -> SubFlow:a-b-C-1-0
parent Flow ID "a",   Step type "b-C" -> SubFlow:a-b-C-1-0
```

When a **waitFor** whose Step type contains "-" returns a **SubFlow\.run**
condition, the server rejects the result as an invalid Worker response. It fails
the attempt without retry, so under the default policy the Flow fails. The
Worker logs a warning that names the Step type. A Step type with "-" that never
starts SubFlows still works. To fix the error, rename the Step type that
**getStepType** returns, for example from "b-C" to "bC".

<a id="example"></a>

## Example

Example: [examples/typescript/src/primitives/subflow/subflow-flow.ts](https://github.com/superdurable/dex/tree/main/examples/typescript/src/primitives/subflow/subflow-flow.ts)