Avoid generating duplicated classes with jsonschema2pojo and sourceType "json"

Question

Following the instructions here, I use the jsonschema2pojo Maven plugin to generate Java classes from JSON example files.

My JSON example file has a structure like this

{
  "coffeeTable": {
    "book": [
      {
        "author": "Aldo Rossi",
        "title": "The Architecture of the City"
      }
    ]
  },
  "bookCase": [
    {
      "book": [
        {
          "author": "Shakespeare",
          "title": "Collected Works"
        }
      ]
    }
  ]
}

When generating Java classes from the JSON example, a class Book and a class Book__1 is generated. Book is used for the books on the coffee table. Book__1 is used for the elements in the book case. I saw that there are solutions for avoiding duplicated classes when generating Java classes with JSON schema files in the documentation. I did not find a solution when using a JSON object directly for code generation. Is it possible to achieve that there is only a single Book class, which is used in both places, generated from the JSON object above? Or do I have to create a JSON schema object from the JSON object and then use the javaType/existingJavaType annotation there to achieve this?

Answer 1

What you can do in this case is make 2 separate json schemas and reference one in the other:

room.json

{
  "title": "room",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "room.json",
  "type": "object",
  "properties": {
    "coffeeTable": {
      "type": "array",
      "items": {
        "$ref": "book.json"
      }
    },
    "bookCase": {
      "type": "array",
      "items": {
        "$ref": "book.json"
      }
    }
  }
}

and book.json

{
    "title": "Book",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "book.json",
    "type": "object",
    "properties": {
        "author": {
            "type": "string"
        },
        "title": {
            "type": "string"
        }
    }
}

This will generate 2 java file: Room.java & Book.java