# CustomState

State defined by supplying Amazon States Language (ASL) in the state machine.

Extends: Construct › State › CustomState
Implements: IChainable, INextable, IConstruct, IDependable

- Source: [`aws-stepfunctions/lib/states/custom-state.ts`](https://github.com/aws/aws-cdk/blob/v2.275.0/packages/aws-cdk-lib/aws-stepfunctions/lib/states/custom-state.ts#L23)
- Type last changed: v2.178.0 · 6 Feb 2025

## Example

```ts
import * as dynamodb from 'aws-cdk-lib/aws-dynamodb';

// create a table
const table = new dynamodb.Table(this, 'montable', {
  partitionKey: {
    name: 'id',
    type: dynamodb.AttributeType.STRING,
  },
});

const finalStatus = new sfn.Pass(this, 'final step');

// States language JSON to put an item into DynamoDB
// snippet generated from https://docs.aws.amazon.com/step-functions/latest/dg/tutorial-code-snippet.html#tutorial-code-snippet-1
const stateJson = {
  Type: 'Task',
  Resource: 'arn:aws:states:::dynamodb:putItem',
  Parameters: {
    TableName: table.tableName,
    Item: {
      id: {
        S: 'MyEntry',
      },
    },
  },
  ResultPath: null,
};

// custom state which represents a task to insert data into DynamoDB
const custom = new sfn.CustomState(this, 'my custom task', {
  stateJson,
});

// catch errors with addCatch
const errorHandler = new sfn.Pass(this, 'handle failure');
custom.addCatch(errorHandler);

// retry the task if something goes wrong
custom.addRetry({
  errors: [sfn.Errors.ALL],
  interval: Duration.seconds(10),
  maxAttempts: 5,
});

const chain = sfn.Chain.start(custom)
  .next(finalStatus);

const sm = new sfn.StateMachine(this, 'StateMachine', {
  definitionBody: sfn.DefinitionBody.fromChainable(chain),
  timeout: Duration.seconds(30),
  comment: 'a super cool state machine',
});

// don't forget permissions. You need to assign them
table.grantWriteData(sm);
```

## Initializer

```ts
new CustomState(scope: Construct, id: string, props: CustomStateProps)
```

## Construct Props

- `stateJson`: { [key: string]: any } (required) — Amazon States Language (JSON-based) definition of the state.

## Properties

- `endStates`: [INextable](/cdk/api/v2/docs/aws-cdk-lib.aws_stepfunctions.INextable.html)[] — Continuable states of this Chainable.

- `id`: string — Descriptive identifier for this chainable.

- `node`: [Node](/cdk/api/v2/docs/constructs.Node.html) — The tree node.

- `startState`: [State](/cdk/api/v2/docs/aws-cdk-lib.aws_stepfunctions.State.html) — First state of this Chainable.

- `stateId`: string — Tokenized string that evaluates to the state's ID.

## Methods

- `addCatch(handler: IChainable, props?: CatchProps): CustomState // chainable` — Add a recovery handler for this state.

  When a particular error occurs, execution will continue at the error
  handler instead of failing the state machine execution.

- `addPrefix(x: string): void` — Add a prefix to the stateId of this state.

- `addRetry(props?: RetryProps): CustomState // chainable` — Add retry configuration for this state.

  This controls if and how the execution will be retried if a particular
  error occurs.

- `bindToGraph(graph: StateGraph): void` — Register this state as part of the given graph.

  Don't call this. It will be called automatically when you work
  with states normally.

- `filterNextables(states: State[]): INextable[]` (static) — Return only the states that allow chaining from an array of states.

- `findReachableEndStates(start: State, options?: FindStateOptions): State[]` (static) — Find the set of end states states reachable through transitions from the given start state.

- `findReachableStates(start: State, options?: FindStateOptions): State[]` (static) — Find the set of states reachable through transitions from the given start state.

  This does not retrieve states from within sub-graphs, such as states within a Parallel state's branch.

- `isConstruct(x: any): boolean` (static) — Checks if `x` is a construct.

  Use this method instead of `instanceof` to properly detect `Construct`
  instances, even when the construct library is symlinked.

  Explanation: in JavaScript, multiple copies of the `constructs` library on
  disk are seen as independent, completely different libraries. As a
  consequence, the class `Construct` in each copy of the `constructs` library
  is seen as a different class, and an instance of one class will not test as
  `instanceof` the other class. `npm install` will not create installations
  like this, but users may manually symlink construct libraries together or
  use a monorepo tool: in those cases, multiple copies of the `constructs`
  library can be accidentally installed, and `instanceof` will behave
  unpredictably. It is safest to avoid using `instanceof`, and using
  this type-testing method instead.

  **Parameters**

  - `x` — Any object.

  **Returns:** true if `x` is an object created from a class which extends `Construct`.

- `next(next: IChainable): Chain` — Continue normal execution with the given state.

- `prefixStates(root: IConstruct, prefix: string): void` (static) — Add a prefix to the stateId of all States found in a construct tree.

- `toStateJson(queryLanguage?: QueryLanguage): json` — Returns the Amazon States Language object for this state.

- `toString(): string` — Returns a string representation of this construct.

- `with(...mixins: IMixin[]): IConstruct` — Applies one or more mixins to this construct.

  Mixins are applied in order. The list of constructs is captured at the
  start of the call, so constructs added by a mixin will not be visited.
  Use multiple `with()` calls if subsequent mixins should apply to added
  constructs.

  **Parameters**

  - `mixins` — The mixins to apply.

  **Returns:** This construct for chaining