additionalProperties is generated with a boolean in swagger2

[ling1726]

When using webapi2swagger with outputType set as swagger2 , the additionalProperties field is generated with a boolean set to false.

This is not correct for swagger2 since the boolean value was only introduced for this field in open api 3

[RicoSuter]

What't the alternative way to express this in Swagger 2?

[ling1726]

In Swagger 2 additionalProperties cannot take a boolean value. Either it is present, or it takes a Schema Object as value

https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#schema-object

https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.0.md#schema-object

See the differences in spec in the above specifications (v2 and v3)

[RicoSuter]

So we should just disable generation of "additionalProperties": false because this is the default for Swagger 2? The default for OpenAPI 3/JSON Schema is true I think so there it is needed... correct?

[ling1726]

I agree with disabling the generation of this field in swagger 2.

I think you can disable it for OpenApi 3 too, since if it's not present the spec assumes that field is true.

On a broader note, how is this property generated if it does take a schema object in NSwag ?

[RicoSuter]

It is generated as a property with an object, e.g. "additionalProperties": { ... }

Currently it is only set to false because the default is true if it is true and has no schema then it is omitted. The big question is what are the defaults of this property for Swagger2/OpenAPI3/JSON Schema?

[ling1726]

The default is only true for OpenAPI3

Swagger2 has no notion of a boolean value for this property

[RicoSuter]

The question is the behavior...

[ling1726]

If you check here https://swagger.io/docs/specification/data-models/data-types/

you'll see that additionalProperties: true is equivalent to additionalProperties: {} which is the default behaviour. setting one of the two previous values, just makes this explicit

[RicoSuter]

you'll see that additionalProperties: true is equivalent to additionalProperties: {} which is the default behaviour

How can I disable additional properties when not setting the property defaults to additionalProperties: {}?

[RicoSuter]

Ref swagger-api/swagger-core#1437 (comment)

[ling1726]

According to that issue thread in swagger, that would should mean that we can assume additionalProperties as false if it isn't present. If the field is present then it should be a JSON Schema.

Only in the OAS v3 spec is additionalProperties: false actually required. As seen in this PR OAI/OpenAPI-Specification#1548

[RicoSuter]

Just nice, what a big mess these whole JSON Schema/Swagger 2/OpenAPI 3 specs are...

[ling1726]

I agree 👍

My main issue here, is swagger v2 parsers/validators might fail at the generated swagger output, since they will not expect this field to have a boolean as a value

[RicoSuter]

Created a PR ... tests missing

[ling1726]

Cool, I'll take a look at it in a bit, unless you want to go ahead and merge it yourself ;)

[RicoSuter]

Please check/review the tests.