Aws-cdk: [aws-stepfunctions-tasks] Problem with mapping a boolean and a number from an input event in a step function to insert into dynamodb

[michaelwiles]

So thank you for upgrading the dynamodb integration from step functions.

I'm now starting to use it.

Firstly, when doing this - the recommended way to map values in a step function:

"alarm_id": DynamoAttributeValue.from_number(JsonPath.number_at("$.detail.alarm_id")),

This is synthesized as "alarm_id":{"N":"-1.8881545897087864e+289"}}

Very weird. Especially since that is what is actually deployed...

Surely that should be

"alarm_id":{"N.$":"$.detail.alarm_id"}}

Then what about when I want to map a boolean?

There is no boolean_at in JsonPath...

So what I really want to know is why access to the constructor of DynamoAttributeValue is not provided because this would solve all my problems...

• **CDK CLI Version:1.51.0
• **Node.js Version: 12.16.3
• **OS: Ubuntu 20.04
• **Language (Version): Python 3.8

[shivlaks]

@michaelbrewer - from_number is for the case where you have a number to directly plug in, you'd want to use number_from_string and pass it the parameter you're currently giving it. can you give that a go and let me know how it turns out?

I'll need to dig into the boolean case a bit more, will take a look a bit later today

[michaelwiles]

Yes, thank you @shivlaks - I looked at some of the tests and ascertained that is the way to do it.

"alarm_id": DynamoAttributeValue.number_from_string(JsonPath.string_at("$.detail.alarmId")),

works great...

Please let me know if you have something on booleans as I can't find an example mapping a boolean in the tests.

[shivlaks]

@michaelwiles are you attempting to set a boolean based on state input (by selecting part of the path?) we might need to add a booleanFromJsonPath method to support that as there's only fromBoolean that's currently available, which will allow you to set a value, but not select it from the state input.

[michaelwiles]

Yes, that's what I am doing - and that's what is needed -> "booleanFromJsonPath"

[michaelwiles]

@shivlaks I've created a pull request for this though it's going to need a bit more attention as I don't think I've followed the process properly.

[shivlaks]

@michaelwiles took a quick glance and provided some feedback. let me know if you're running into any issues iterating.
I'm happy to help get this PR filled out and past the goal line :)

[michaelwiles]

thank you. will follow up