How to specify a property can be null or a reference with swagger

Question

How to specify a property as null or a reference? discusses how to specify a property as null or a reference using jsonschema.

I\'m looking to do the same thing with

Answer 1

Not easy to do that. Even almost impossible. Your options :

Wait

There is a very long discussion about this point, maybe one day it will be done...

Use vendors extensions

You can use vendors extensions like x-oneOf and x-anyOf. I have already taken this hard way: You must to upgrade all used 'swagger tools' to take into account these vendors extensions.

In my case, we needed 'only' to :

• Develops our own Jax-RS parser with customized annotations in order to extract swagger API file from sources
• Extends swagger-codegen to take into account these extensions to generate java code for our clients
• Develops our own swagger-ui: to facilitate this work, we added a preprocessing step to convert our swagger schema with our extensions to a valid json schema. It's easier to find a module to represent json schemas than swagger schemas in javascript. By cons we gave up the idea to test the API with the 'try it' button.

It was a year ago, maybe now ...

Refactor your APIs

Many projects don't need anyOf and oneOf, why not us ?

Answer 2

In OpenAPI 3.0, you can use:

"foo": {
    "nullable": true,
    "allOf": [
        {
            "$ref": "#/definitions/Foo"
        }
    ]
}

YAML version:

foo:
  nullable: true
  allOf:
  - $ref: '#/definitions/Foo'

Wrapping $ref into allOf is needed to combine the $ref with other keywords - because $ref overwrites any sibling keywords. This is further discussed in the OpenAPI Specification repository: Reference objects don't combine well with “nullable”