discriminator support?

[fingon]

Swagger 2.0 has 'discriminator' field, which is essentially used to choose the schema to use based on contents of the field. At least apispec 0.6 does not have this (nor does actually marshmallow itself, +- marshmallow-polyfield which is similar but helps choose type of field instead of the whole object's schema).

Any plans on this?

[sloria]

There are no near-term plans for this, but I would certainly review a PR for it.

[lafrech]

Ideally, I would add

discriminator = 'field_name'

to the Meta of the Schema.

But if I do that, I don't know where to get 'discriminator' back. It is lost in SchemaOpts.__init__ in Marshmallow, which only picks a whitelist of attributes.

Also, it is a bit misleading that discriminator appears in _VALID_PROPERTIES, which is used in field2property but not in schema2parameters. AFAIK, it is only useful for a schema, not for a field.

Right now, what I do is add 'x-discriminator': 'field_name' when calling definition on my schema:

api.definition('MySchema')(schema, **{'x-abstract': True, 'x-discriminator': 'kind'}

This works because I added a schema definition registration helper to my framework to pass 'x-' attributes to the spec: https://github.com/Nobatek/flask-rest-api/blob/master/flask_rest_api/spec/plugin.py#L111

The whole inheritance mechanism is not well defined in OpenAPI yet so I only rely on x- properties.

[sloria]

This is now supported via the extra_fields parameter to definition:

spec.definition('Pet', extra_fields={'discriminator': 'pet_type'})