JSON backward compatibility check for adding non-required fields

JSON backward compatibility check for adding non-required fields

Hello,

I am testing the JSON compatibility for adding non-required fields. There are multiple cases when adding fields in JSON Schema that seem incorrect. This cases should be work without “additionalItems”: false but when I remove it the check compatibility update is failed.

For example,

1. Should be backward compatible without “additionalItems”: false

"original": {
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "array",
  "items": [
    {
      "type": "string"
    },
    {
      "type": "number"
    }
  ]
},
"updated": {
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "array",
  "items": [
    {
      "type": "string"
    },
    {
      "type": "number"
    },
    {
      "type": "boolean"
    }
  ]
}

1. Should be backward compatible without “additionalItems”: false

"original": {
        "$schema": "http://json-schema.org/draft-07/schema#",
        "type": "object",
        "properties": {
          "postal_code": {
            "type": "number"
          },
          "street": {
            "type": "string"
          }
        }
      },
      "updated": {
        "$schema": "http://json-schema.org/draft-07/schema#",
        "type": "object",
        "properties": {
          "postal_code": {
            "type": "number"
          },
          "street": {
            "type": "string"
          },
          "country": {
            "type": "string"
          }
        },
        "additionalProperties": {
          "type": "string"
        }
      }

1. Also the case should be failed because in updated schema should be only “type”: “string” properties

"original": {
        "$schema": "http://json-schema.org/draft-07/schema#",
        "type": "object",
        "properties": {
          "postal_code": {
            "type": "number"
          },
          "street": {
            "type": "string"
          }
        },
        "additionalProperties": false
      },
      "updated": {
        "$schema": "http://json-schema.org/draft-07/schema#",
        "type": "object",
        "properties": {
          "postal_code": {
            "type": "number"
          },
          "street": {
            "type": "string"
          },
          "country": {
            "type": "string"
          }
        },
        "additionalProperties": {
          "type": "string"
        }
      }

What do you think about it?

[jsenko]

Thanks for the discussion. This happens exactly because additionalProperties: true, but would be ok if additionalProperties: false.

[arturkandur]

But there is a possibility we will add a less strict mode in the future if it is useful.

It will be good feature I think. In my case I want to update json schemas backward compatible and clients forget to add additionalProperties: false to schema from the start. So if they want to update it, they need to create new one because it is more strict and not possible to add additionalProperties: false or new field. That’s why I raise this question.