Is it possible to validate objects that lack a required property with a default value?

[dhalfageme]

Hi!. Lets say I have this schema:

  "$schema": "http://json-schema.org/2020-12/schema#",
  "$id": "test",
  "title": "Product",
  "description": "A product from the catalog",
  "type": "object",

  "properties": {
    "complexObject": {
      "type": "object",
      "required": ["id"],
      "properties": {
        "id": {
          "description": "The unique identifier for a product",
          "type": "integer",
          "default": 2
        },
        "name": {
          "description": "Name of the product",
          "type": "string"
        }
      }
    }
  }
}

And this object.

{
  "complexObject": { "name":  "product name"}
}

The object doesn't validate using everit-org/json-schema java validor because it lacks of complexObject.idproperty, which has a default value. I put a nested property to be as much general as possible.

I would like to pass validation and build a new JSON object using default values for missing properties.

Thanks.

[gregsdennis]

The default keyword doesn't perform any validation. It's an annotation-only keyword. This means that its purpose is to provide it's value to the application, and the application should determine what to do with that information.

Thus, your instance doesn't validate because id is absent.

My suggestion would be to make id optional (just don't list it in required), which would allow your instance to pass. One the validation has passed, it should be accompanied by any annotations. From there, you can decide what to do with them.

[dhalfageme]

@gregsdennis Sorry for the out of scope response to your original answer

So if I would like to do this default population, because it's a requirement, would I have to make some custom implementation that creates the properties when applying the new schema? There's no a workaround for this, right?

I have hundreds of objects that I would like to evolve to new schema definitions and provide valid values when reading them

[Relequestual]

Yes, I mean that you evaluate the schema, then collect the annotations and alter the data, and then use the new data with defaults in your application to do whatever you need to do.

Is this something your implementation can do? Collect annotations by evaluation without an instance?

I guess it wouldn't actually be that complex to do unless references are used.

[dhalfageme]

Yeah @Relequestual, I am looking for some way to perform that... If you @karenetheridge know a way to get this working, it is now the real problem, not only to make the validation pass, also to provide valid values when reading the objects that lack properties with defaults.

[Relequestual]

AJV can do this out of the box, but I don't know what language you're working with.

[dhalfageme]

I am using Java

[awwright]

For some more discussion on why "default" doesn't work this way (by default), see json-schema-org/json-schema-spec#867