How to validate an optional json value

Question

I try to validate a json response (just like in the example below from the website), but I fail on validation optional elements. I can only validate mandatory elements with 'validate', because if the json-path failes, it already counts as failed.

Can anybody get me a hint on how to validate a value, IF AND ONLY IF the element exists? If it does not exist (optional), it is good also...

Example if have to validate : The description is optional, but if it is set, it should not be longer than 30 characters.

http()
    .client(todoClient)
    .receive()
    .response(HttpStatus.OK)
    .messageType(MessageType.JSON)
    .validate("$.id", "${todoId}")
    .validate("$.title", "${todoName}")
    .validate("$.description", "${todoDescription}");

Answer 1

May be this post can help you, there is the use of Matchers. https://stackoverflow.com/a/50817190/11770752

First you can try Matchers.hasValue , if so you check with Matchers.hasSize .

Otherwise i found the .jsonPath(String jsonPathExpression, Object controlValue) after .messageType(MessageType.JSON) but i don't know if it does check for optionals or even validates the Json Value.

EDIT: As is was browsing the Documentation there is the option of Validation Matchers in Citrus. http://citrusframework.org/reference/html/index.html#validation-matcher

Replace "${todoDescription}" with "@matches('\\w{30}')@" , it should work.