(aws-stepfunctions): Condition.jsonata does not support multiline string

[MathieuGilbert]

Describe the bug

Condition.jsonata constructor validation fails for a multi-line JSONata strings. This is possible in other places.

const fails = `{%
  true
%}`

const works = `{% true %}`

Regression Issue

• Select this option if this issue appears to be a regression.

Last Known Working CDK Library Version

No response

Expected Behavior

It should allow multiline JSONata strings, correctly detecting the opening and closing tags.

Current Behavior

Using a multiline template literal in Typescript as the condition:

const condition = `{%
  true
%}`

Condition.jsonata(condition)

Throws the following on cdk synth:

JSONata expression must be start with '{%' and end with '%}', got '{%
  true
%}'

From here: https://github.com/aws/aws-cdk/blob/main/packages/aws-cdk-lib/aws-stepfunctions/lib/condition.ts#L471

Reproduction Steps

The resultJsonata is fine as multiline, but the conditionJsonata won't synth unless it's put on one line, ie. const conditionJsonata = `{% true %}`;

import { Stack } from "aws-cdk-lib";
import {
  Choice,
  Condition,
  DefinitionBody,
  Pass,
  StateMachine,
} from "aws-cdk-lib/aws-stepfunctions";
import { Construct } from "constructs";

export class ConditionStack extends Stack {
  constructor(scope: Construct, id: string) {
    super(scope, id);

    const conditionJsonata = `{% 
      true 
    %}`;
    const resultJsonata = `{% 
      "passed"
    %}`;

    const choice = Choice.jsonata(this, `${id}-Choice`);
    const condition = Condition.jsonata(conditionJsonata);
    const pass = Pass.jsonata(this, `${id}-Pass`, {
      outputs: {
        result: resultJsonata,
      },
    });

    const definition = choice.when(condition, pass);

    new StateMachine(this, `${id}-StateMachine`, {
      definitionBody: DefinitionBody.fromChainable(definition),
    });
  }
}

Possible Solution

The validation could be updated to add the s "dotAll" flag to the regex: if (!/^{%(.*)%}$/s.test(condition)) {
or a simpler non-regex if (!(condition.startsWith("{%") && condition.endsWith("%}"))) {.

Additional Information/Context

No response

AWS CDK Library version (aws-cdk-lib)

2.190.0

AWS CDK CLI version

2.1019.2 (build c29855e)

Node.js Version

20.17.0

OS

Mac

Language

TypeScript

Language Version

No response

Other information

No response

[pahud]

Hi @MathieuGilbert

Yes, I've successfully reproduced this issue. Here are the key findings:

Environment:
• aws-cdk-lib: 2.221.1 (latest)
• Node.js: 20.17.0

Results:

❌ Multiline JSONata FAILS:
typescript
const conditionJsonata = `{%
  true
%}`;

Error: JSONata expression must be start with '{%' and end with '%}', got '{% \n      true \n    %}'

✅ Single-line JSONata WORKS:

const conditionJsonata = `{% true %}`;

Synth successful!

The analysis indicates this is a valid concern with the regex validation pattern in the JsonataCondition class. The regex /^{%(.*)%}$/ doesn't match newline characters by default because the . metacharacter excludes line terminators unless the s (dotAll) flag is used.

Your suggested solutions are both valid:

1. Adding the s flag: /^{%(.*)%}$/s
2. Using string methods: condition.startsWith("{%") && condition.endsWith("%}")

The same pattern also appears in isJsonataExpression in task-utils.ts, so both locations would need to be updated for consistency.

Would you be interested in submitting a PR to fix this? The change is straightforward and would benefit the community. If you'd like to contribute, please update both validation locations and consider adding test cases for multiline JSONata expressions.

[pahud]

As there seems to workaround, hence making it a p1.

[MathieuGilbert]

The same pattern also appears in isJsonataExpression in task-utils.ts, so both locations would need to be updated for consistency.

Would you be interested in submitting a PR to fix this? The change is straightforward and would benefit the community. If you'd like to contribute, please update both validation locations and consider adding test cases for multiline JSONata expressions.

Hi @pahud, thanks for looking at this. Yes I should be able to work on a PR updating both spots and with unit tests.

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