Karate API json response - How to validate the presence of a key which sometimes come and sometimes not in the API response

Question

I need help in validating the presence of one key in the response. The response of the API looks like -

"persons": [
        {
            "id": "27",
            "source": {
                "personId": 281,
                "emailAddress": "[email protected]",
                "firstName": "Steve"
            }
        },
        {
            "id": "28", 
            "source": {
                "personId": 353,
                "emailAddress": "[email protected]",
                "firstName": "John"
                "LastName" : "Cena"         
            }
        }
    ]
}

I want to assert if the source.LastName appears or not and if it does then it should always hold a string value.

The solution should be generic and it should work for 30 or 40 persons object also down the time, currently I am using karate version 0.9.4 and need a resolution for handling such scenarios.

Thanks in advance !

Answer 1

In the schema "##string" validates that the field can be null or a string.

Sample Code:

Feature: Schema validation

    Scenario:
        * def resp =
            """
            {
            "persons": [
                    {
                        "id": "27",
                        "source": {
                            "personId": 281,
                            "emailAddress": "[email protected]",
                            "firstName": "Steve"
                        }
                    },
                    {
                        "id": "28", 
                        "source": {
                            "personId": 353,
                            "emailAddress": "[email protected]",
                            "firstName": "John",
                            "LastName" : "Cena"         
                        }
                    }
                ]
            }
            """
        * def schema = 
        """
            {
                "id": "#string",
                "source": {
                    "personId": "#number",
                    "emailAddress": "#string",
                    "firstName": "#string",
                    "LastName": "##string"
                }
            }

        """
        * match each resp.persons == schema