nullable fields in swagger on node.js

Question

I\'ve spent a bunch of time trying to find a solution for creating swagger docs in Node.JS. The main library is swagger-node, in which you create a swagger yaml file and the

Answer 1

SwaggerUI doesn't support nullable types (please, see here). But I used nullable properties as:

type: ['string','null']

After that this property disappears from UI, but validation still worked.

Answer 2

Just as a hint, because I stumpled upon this: When I added

type: string
nullable: true`

as described in the answer https://stackoverflow.com/a/42797352/2750563 my service returned only "fieldName": { "present": true } instead of an actual value!

If you see this, simply add the JsonNullableModule to your Jackson serializer, for example, if using Spring:

@Component
public class JacksonConfiguration {

    @Autowired
    public void configureJackson(ObjectMapper mapper) {
        mapper.registerModule(new JsonNullableModule());
    }

}

Then everything looks fine again.

Answer 3

Instead of add null in type property, you can use default property instead.

Swagger.json property definition example:

"due_date": {
  "type": "string",
  "description": "Due date",
  "default": "null"
},

It's a valid Swagger type definition, and still appears as expected in Swagger UI.

Answer 4

nullable field is supported in OpenAPI (fka Swagger) Specification v3.0.0, but not in v2.0. Nullable types are defined as follows:

# Can be string or null
type: string
nullable: true