Validate schemas using ex_json_schema

[fenollp]

Following on #23 (and my attempt at solving it: #42), I have been instead using the really good ex_json_schema.

Here is the code I am using:

    case %{
           "components" => components,
           "additionalProperties" => false,
           "type" => "object",
           "required" => [schema_name],
           "properties" => %{
             schema_name => %{"$ref" => "#/components/schemas/#{schema_name}"}
           }
         }
         |> ExJsonSchema.Schema.resolve()
         |> ExJsonSchema.Validator.validate(resp)

There needs to be a translation step first though, to rewrite nullable: true and such incompatibilities of OpenAPIV3 schemas with JSON Schema Draft-04.

Would you be open to use ex_json_schema validators instead of the current ones in this lib?
Where do you think this translation step should be: within this lib or within ex_json_schema?

Thanks

[mbuhot]

I'd be OK with using ex_json_schema for validations. As you say, it just needs to be possible to map swagger schemas to json schema.

It would be great if there was a mode: swagger option in ex_json_schema, but if you want to get something working immediately we'd need to map it in open_api_spex.

[fenollp]

The people over at OpenAPI and at JSON Schema want to converge their schema specs eventually. To me it makes more sense to do a conversion to (and from?) JSON Schema before validation.

In which module do you think this conversion step should go?

[fenollp]

@moxley why is this labeled as wontfix? Thanks.

[moxley]

@fenollp: The Won't Fix label is only tentative, but requires further discussion to be sure. From what I understand, JSON Schema isn't compatible with Open API. Open API borrows much from JSON Schema, but it extends and modifies it. Here are some of the details of the differences: https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#schema-object. I don't think it's feasible to swap in a JSON Schema library.

By the way, we set up a private channel in the Elixir Slack for discussions. Would you be willing to join us there? You've already been added.

[mbuhot]

Looks like this can be achieved when OpenApi 3.1 is released.
OpenAPI schemas will be a proper superset of the latest json schema draft 🎉

OAI/OpenAPI-Specification#1977