(aws_stepfunctions): Depreciated Parameters field in Map

[grzegorzewald]

Describe the feature

As per https://docs.aws.amazon.com/step-functions/latest/dg/concepts-asl-use-map-state-inline.html#map-state-inline-deprecated-fields, Parameters filed is now depreciated. ItemSelector field should be used instead (https://docs.aws.amazon.com/step-functions/latest/dg/concepts-asl-use-map-state-inline.html#itemselector)

Use Case

Depreciated fields may break compatibility

Proposed Solution

As new ItemSelector filed takes input in exactly the same form as depreciated 'Parameters', the easiest solution would be to rename field and create "alias" with depreciation warning durning synth.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.53.0

Environment details (OS name and version, etc.)

MacOS 13.0.1

[peterwoodworth]

To be clear, you're referring to this parameter which will end up rendering like this?

aws-cdk/packages/@aws-cdk/aws-stepfunctions/lib/states/map.ts

Line 212 in 7690f43

Parameters: this.parameters,

[grzegorzewald]

Hi @peterwoodworth,
Yes, exactly this one.

[shantgup]

My customer is trying to use ItemSelector with CDK, only to find that Map does not support ItemSelector.

I have suggested them to use the deprecated Parameters field for now.

The documentation here states that it's highly recommended to use ItemSelector instead of Parameters, but CDK users will not be able to follow this recommendation due to missing support for ItemSelector in the CDK construct.

The ItemSelector field replaces the Parameters field within the Map state. If you use the Parameters field in your Map state definitions to create custom input, we highly recommend that you replace them with ItemSelector.

[MorelSerge]

Been a bit disappointed with the supported of Map in the CDK in general. First tried to find a way to use distributed mode: node supported, using ItemSelector as the alternative -> also not supported :/

[7jpsan]

Hi, @grzegorzewald probably not canonical (but a workaround) but I had a similar issue and while we wait the native cdk class Map support for it, we can use a CustomState based off the MapState and tweak a couple props:

const mapState = new sfn.CustomState(this, 'MapWithSelector', {
            stateJson: {
                ...new sfn.Map(this, 'Irrelevant', {
                    itemsPath: sfn.JsonPath.stringAt('$.parallelInputData'),
                })
                    .iterator(yourIteratorGoesHere)
                    .toStateJson(),
                End: undefined,
                ItemSelector: {
                    'ContextIndex.$': '$$.Map.Item.Index',
                    'ContextValue.$': '$$.Map.Item.Value',
                },
            },
        });

This will create the Map state with the ItemSelector on it.

[T-Guerrero]

IMO, this request shouldn't be labeled as "feature request". It's actually an inconsistency with the official doc, thus "bug" looks a better classification for me (even for prioritization purposes)

[joa44741]

would also love to use the ItemSelector instead of Parameters :)

[guyernest]

From the Step Functions Documentation for Map (https://docs.aws.amazon.com/step-functions/latest/dg/concepts-asl-use-map-state-inline.html) under the Deprecated fields:

Note
Although you can continue to include Map states that use the following fields, we highly recommend that you replace Iterator with ItemProcessor and Parameters with ItemSelector.

The current map.iterator implementation ignores this note, and there is no support for the recommended definition.

The only way around it is to use the custom tast option.

[github-actions]

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