@types endpoint will fail with types with fields defining non-parametrized widgets

[elioschmutz]

Having a type with a schema defining the following field:

form.widget(field1=TextWidget)
field1 = schema.TextLine(title=u"Tagged Values widget params")

and requesting:

curl -H "Accept: application/json" --user "admin:admin" "http://localhost:8080/Plone/@types/MyType

will raise the following error:

  Module ZPublisher.Publish, line 138, in publish
  Module ZPublisher.mapply, line 77, in mapply
  Module ZPublisher.Publish, line 48, in call_object
  Module plone.rest.service, line 23, in __call__
  Module plone.restapi.services, line 19, in render
  Module plone.restapi.services.types.get, line 53, in reply
  Module plone.restapi.types.utils, line 206, in get_jsonschema_for_portal_type
  Module plone.restapi.types.utils, line 175, in get_jsonschema_for_fti
  Module plone.restapi.types.utils, line 141, in get_tagged_values
AttributeError: 'str' object has no attribute 'params'

Problem

To set a widget of a field, you'll use plone.autoforms widget-directive (https://github.com/plone/plone.autoform/blob/master/plone/autoform/directives.py#L76). If you take a closer look at this function, you'll see, that there are two different possibilities, how to set a widget.

The first on is to pass keyword-args

widget(field1='z3c.form.browser.text.TextWidget', field2=TextWidget)

The second is to pass positional-args:

widget('field1', TextWidget, label=u'My label')

Using positional-args will create a ParameterizedWidget-factory (https://github.com/plone/plone.autoform/blob/master/plone/autoform/directives.py#L137). Using the keyword-args will generate a string to identify the widget (https://github.com/plone/plone.autoform/blob/master/plone/autoform/directives.py#L129).

The get_tagged_values-function will fail (https://github.com/plone/plone.restapi/blob/master/src/plone/restapi/types/utils.py#L142) if you set a widget through keyword-args, because this function assumes a ParametrizedWidget factory.