How to generate json data from Json Schema Programmatically in Java

Question

I am trying to create Body-parameter(JSON) for my POST Api , which is a JSON request . All I have is the JSON Schema . I am trying to come up with a list of different JSON test data covering Positive and negative flows for it .

Is there any option to generate / create the JSON data programmatic using Java ? . I have attached a small Json schema (just for understanding purpose) but my actual schema is more complicated with lot of Array's and Nested Json's .

My Json Schema :

{
"$schema": "http://json-schema.org/draft-07/schema",
"$id": "http://example.com/example.json",
"type": "object",
"title": "The Root Schema",
"description": "The root schema comprises the entire JSON document.",
"required": [
    "FirstName",
    "LastName",
    "Age",
    "Interest"
],
"properties": {
    "FirstName": {
        "$id": "#/properties/FirstName",
        "type": "string",
        "title": "The Firstname Schema",
        "description": "An explanation about the purpose of this instance.",
        "default": "",
        "examples": [
            "Vijay"
        ]
    },
    "LastName": {
        "$id": "#/properties/LastName",
        "type": "string",
        "title": "The Lastname Schema",
        "description": "An explanation about the purpose of this instance.",
        "default": "",
        "examples": [
            "Karthik"
        ]
    },
    "Age": {
        "$id": "#/properties/Age",
        "type": "integer",
        "title": "The Age Schema",
        "description": "An explanation about the purpose of this instance.",
        "default": 0,
        "examples": [
            30
        ]
    },
    "Interest": {
        "$id": "#/properties/Interest",
        "type": "array",
        "title": "The Interest Schema",
        "description": "An explanation about the purpose of this instance.",
        "default": [],
        "items": {
            "$id": "#/properties/Interest/items",
            "type": "string",
            "title": "The Items Schema",
            "description": "An explanation about the purpose of this instance.",
            "default": "",
            "examples": [
                "Food",
                "movie",
                "Learning",
                "VideoGames"
            ]
        }
    }
}

} enter code here

My TestData looks like :

 {
"FirstName":"Vivi",
"LastName":"Karrri",
"Age":30,
"Interest":["Food","movie","Learning","VideoGames"]
}

Any suggestions how can we achive this ? Note : I am using Springboot and I have complete POJO for the request object

Answer 1

You can generate fake java-objects and then map them to JSON.

POJOs

If you already have the POJOs matching the schema, then we can skip this step. If no, to generate a POJO from the schema, for example, can be used this library: jsonschema2pojo .

Fake objects

Generating of objects with fake data can be done with a special library, some of them are listed here:

• easy-random
• podam
• java-faker

Generating JSON

It's prettry simple and can be done with Jackson:

ObjectMapper objectMapper = new ObjectMapper();
ObjectWriter prettyPrinter = objectMapper.writerWithDefaultPrettyPrinter();
String json = prettyPrinter.writeValueAsString(yourFakeObject);

Answer 2

If you have json schema then you can directly generate a sample JSON message from it.

https://github.com/jignesh-dhua/json-generator