How can i assign validators to a behavior wich is assigned at runtime?

Plone Support Add-on Development
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1

My use case: in a setuphandler i iterate over all DX-Type defintions and add a behavior. That's ok and do what i need:

# setuphandlers.py 

def add_taxonomy_to_fti(context):

    taxonomy = schema.Set(
        title=_("taxonomy_studiengang"),
        description=_("Select Course and Semester"),
        required=False,
        value_type=schema.Choice(
            vocabulary="collective.taxonomy.taxonomies",
        ),
    )
    portal = api.portal.get()
    portal_types = portal.portal_types
    _behavior = "collective.taxonomy.generated.studienablauf"

    for dxtype in TYPES_FOR_TAXONOMY:

        fti = portal_types.get(dxtype)

        if _behavior in list(fti.behaviors):
            continue

        fti.behaviors = fti.behaviors + (_behavior,)
        typeschema = fti.lookupSchema()
        schemaeditor = IEditableSchema(typeschema)
        fieldname = "taxonomy_studienablauf"
        
        try:
            schemaeditor.removeField(fieldname)
        except ValueError:
            logger.info(
                "Fieldname for Taxonomy not found {} {}".format(dxtype, fieldname)
            )
        finally:
            notify(FieldRemovedEvent(fti, taxonomy))

        notify(SchemaInvalidatedEvent(portal_type=dxtype))

        schemaeditor.addField(
            taxonomy,
            name=fieldname,
        )
        notify(ObjectAddedEvent(taxonomy, typeschema))
        notify(FieldAddedEvent(fti, taxonomy))
        notify(SchemaInvalidatedEvent(portal_type=dxtype))

# validators.py
from collective.taxonomy.interfaces import ITaxonomySelectWidget
from z3c.form import validator
from z3c.form.interfaces import IOrderedSelectWidget
from z3c.form.validator import SimpleFieldValidator
from zope.component import provideAdapter
from zope.interface import Invalid


class CourseOfStudiesValidator(SimpleFieldValidator):
    """z3c.form validator class for studiumsablauf taxonomy"""

    def validate(self, value):

        print("in my validation method")

        """Validate selected items count from the list, should be greater zero"""
        super(CourseOfStudiesValidator, self).validate(value)
        if not value:
            raise Invalid("My custom error message")


validator.WidgetValidatorDiscriminators(
    CourseOfStudiesValidator, widget=IOrderedSelectWidget
)

validator.WidgetValidatorDiscriminators(
    CourseOfStudiesValidator, widget=ITaxonomySelectWidget
)

provideAdapter(CourseOfStudiesValidator)

My Validator doesn't match. I didn't see the print statement if i submit the Add Form. My Question is: how can i assign a validator?

2

This post is already dated. However, I came across the issue of not being able to use the same validator class for another schema interface. The sample code in this post is doing the same. Apparently it is a z3cform issue:

My solution was to create another class the same way it is implemented here.

I thought of posting this information to help others who will encounter the same issue.