custom ASDF validators

[CagtayFabry]

some thoughts and ideas regarding implementations of custom ASDF validators

handling $ref

any validation keywords that are on the level of a $ref: statement seem to be dropped (validation does not get triggerd)
example:

properties:
  length_prop:
    $ref: tag:stsci.edu:asdf/unit/quantity-1.1.0
    wx_unit: "s" # this does not trigger a validator on wx_unit
wx_unit:
  length_prop: "m" # this works as expected

See asdf-format/asdf#814 for details and workaround using tag validator

type: object
properties:
  quantity_prop:
    description: |
      a simple quantity with custom validator
    tag: tag:stsci.edu:asdf/unit/quantity-1.1.0
    wx_unit: "s"

registering validators

apparently registering a validator for one class might enable the validator on a global extension level. This might be useful but we should check "overriding" validator keywords with different functions for seperate classes.

See asdf-format/asdf#815 (comment) for explanation of current implementation

handling anyOf / oneOf

UPDATE: this was fixed by defining better (tighter) restrictions on anyOf subtypes (i.e. well defined required with additionalProperties: false)
Use of oneOf is encouraged once asdf-format/asdf#811 is available (see asdf-format/asdf#809)

[CagtayFabry]

Closing for now since most of the issues have been solved or implemented.