(golang) awscdk/v2/awsiot: CfnTopicRule_DynamoDBv2ActionProperty empty generated cfn

What is the problem?

When I construct a TopicRule using CfnTopicRule_DynamoDBv2ActionProperty, then the generated CloudFormation is missing the actual action details.

Reproduction Steps

	ddbV2Action := &awsiot.CfnTopicRule_ActionProperty{
		DynamoDBv2: &awsiot.CfnTopicRule_DynamoDBv2ActionProperty{
			PutItem: awsiot.CfnTopicRule_PutItemInputProperty{
				TableName: table.TableName(),
			},
			RoleArn: iotRole.RoleArn(),
		},
	}

	ruleprops := &awsiot.CfnTopicRuleProps{
		TopicRulePayload: awsiot.CfnTopicRule_TopicRulePayloadProperty{
			Actions:          &[]*awsiot.CfnTopicRule_ActionProperty{ddbV2Action},
			AwsIotSqlVersion: aws.String("2016-03-23"),
			Sql:              aws.String(sqlStatement),
		},
	}

	awsiot.NewCfnTopicRule(stack, aws.String("ExampleRule"), ruleprops)

What did you expect to happen?

I expected the Output to look like this:

  Type: AWS::IoT::TopicRule
    Properties:
      TopicRulePayload:
        Actions:
          - DynamoDBv2:
              PutItem:
                TableName:
                  Ref: <table name redacted>
              RoleArn:
                Fn::GetAtt:
                  - IoTtoDynamoDBRole47C5C8A5
                  - Arn
        AwsIotSqlVersion: "2016-03-23"
        Sql: <sql redacted>

What actually happened?

I only see this:

  Type: AWS::IoT::TopicRule
    Properties:
      TopicRulePayload:
        Actions:
          - DynamoDBv2: {}
        AwsIotSqlVersion: "2016-03-23"
        RuleDisabled: false
        Sql: <sql redacted>

CDK CLI Version

2.0.0 (build 4b6ce31)

Framework Version

No response

Node.js Version

v17.2.0.

OS

macOS Monteray

Language

Go

Language Version

Go 1.17.3

Other information

A workaround:

ddbV2Action := &awsiot.CfnTopicRule_ActionProperty{
		DynamoDBv2: &awsiot.CfnTopicRule_DynamoDBv2ActionProperty{
			PutItem: awsiot.CfnTopicRule_PutItemInputProperty{
				TableName: table.TableName(),
			},
			RoleArn: iotRole.RoleArn(),
		},
	}

	ruleprops := &awsiot.CfnTopicRuleProps{
		TopicRulePayload: awsiot.CfnTopicRule_TopicRulePayloadProperty{
			Actions:          &[]*awsiot.CfnTopicRule_ActionProperty{ddbV2Action},
			AwsIotSqlVersion: aws.String("2016-03-23"),
			Sql:              aws.String(SqlString),
		},
	}

	bytes, err := json.MarshalIndent(ruleprops, "", "    ")
	if err != nil {
		panic(err)
	}

	correctProps := &awsiot.CfnTopicRuleProps{}
	err = json.Unmarshal(bytes, correctProps)
	if err != nil {
		panic(err)
	}

	awsiot.NewCfnTopicRule(stack, aws.String("EampleRule"), correctProps)

[karl-dau]

@skinny85 Thanks! that was it!

I got confused with optionals being pointer types and building up those structs with values and not pointers. The JSON marshal/unmarshal trick works because the reflection code dereferences those pointers. I guess everything taking interface{} also did not help.

[skinny85]

BTW, we now have Layer 2 IoT constructs: https://docs.aws.amazon.com/cdk/api/latest/docs/aws-iot-readme.html, you might want to check them out!