Json Question posted in
Our archive of expertly curated questions and answers provides insights and solutions to common problems related to this popular data interchange format. From parsing and manipulating JSON data to integrating it with various programming languages and web services, our archive has got you covered. Start exploring today and take your JSON skills to the next level

How to validate JSON to ensure all fields are non-empty and age is >0?

Through a Rest API endpoint, I accept JSON and using a Kafka Producer, I publish the JSON to a topic. The JSON will have this format:

{
  "id": "uniqueIdentifier",
  "name": "PersonName",
  "age": PersonAge
}

and the send message method in my Kafka Producer looks like this:

public void sendMessage(Person p){

        LOGGER.info(String.format("Message sent -> %s", p.toString()));

        Message<Person> message = MessageBuilder
                .withPayload(p)
                .setHeader(KafkaHeaders.TOPIC, "jsonTopic")
                .build();

        kafkaTemplate.send(message);

    }

I need to check if the JSON has all the fields non-empty and if the age > 0.
How would I need to implement the verification before sending the message?

Tags:

2

Answers


  1. 0

    JSON Schema is the best for this use case. There are libraries in all languages to validate an input JSON against JSON-Schema. E.g. Java, Javascript

    The schema for your requirement should look like the following:

    {
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "id": {
      "type": "string",
      "minLength": 1
    },
    "name": {
      "type": "string",
      "minLength": 1
    },
    "age": {
      "type": "integer",
      "minimum": 1
    }
  },
  "required": ["id", "name", "age"],
  "additionalProperties": false
}

    Here, additionalProperties ensures that you do not allow anything else apart from the declared properties.

    These validation libraries give very detailed validation errors that make the error actionable for the sender/caller:

    {
   "errors" : {
      "required" : "the field 'age' should be have a minimum value as 1"
    }
}
    Login or Signup to reply.
  2. 0

    • For the Person POJO I would suggest the member variables to have @NotNull – to ensure the value for each member variable is provided.

    • Use @Min(1) to have a value more than 0 for age.

    • When declaring the method do as public void sendMessage(@Valid Person p) to ensure validation is done on invoking the method.

    On error handling do the following:

    • Create an exception class like below:
    public class BadRequestException extends RuntimeException {
    public BadRequestException(String message) {
        super(message);
    }
}

    Above can be thrown incase any condition above is thrown. But it needs to be caught using an advice as below:

    @ControllerAdvice
public class MyAdvice {
@ExceptionHandler(HttpMessageNotReadableException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ResponseBody
    public ResponseEntity<String> getHttpMessageNotReadableExceptionException(HttpMessageNotReadableException exception) {
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(exception.getMessage());
    }
}

    Above will give you appropriate message for the malformed payload.

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search