LinkML¶

In general LinkML schemas can be exported to JSON Schema and JSON-LD contexts in order to build a OO-LD schema. With https://github.com/linkml/linkml/pull/2369 lifecycle methods being added to the LinkML jsonschemagen which allow to use annotations to extend the generated schema.

As an example applying

OOLDSchemaGenerator.py

from pprint import pprint
from linkml.generators.jsonschemagen import JsonSchemaGenerator, JsonSchema
from linkml.generators.jsonldcontextgen import ContextGenerator 
import jsonasobj2
import json
import yaml

class OOLDSchemaGenerator(JsonSchemaGenerator):

    def generate_annotations(self, target):
        annotations = jsonasobj2._jsonobj.as_dict(target.source.annotations)
        schema_annotations = {}
        for key in annotations:
            schema_annotations[annotations[key]['tag']] = annotations[key]['value']
        if len(annotations) > 0:
            target.schema_ = {**target.schema_, **schema_annotations}
        return target

    def after_generate_class(self, cls, sv):
        self.generate_annotations(cls)
        return cls

    def after_generate_class_slot(self, slot, cls, sv):
        self.generate_annotations(slot)
        return slot

    def generate(self):
        _schema = super().generate()
        _context = json.loads(ContextGenerator(self.schema).serialize())
        oold = JsonSchema({"@context": _context["@context"], **_schema})
        return oold

    def serialize(self, **kwargs) -> str:
        return self.generate().to_json(sort_keys=False, indent=self.indent if self.indent > 0 else None)

if __name__ == "__main__":
    print(yaml.dump(json.loads(OOLDSchemaGenerator('Person.min.linkml.yaml', include_null=False).serialize()), sort_keys=False, indent=2))

on an annotated LinkML schema, e.g.

Person.linkml.yaml

id: https://example.org/Person/
name: Person
prefixes:
      linkml: https://w3id.org/linkml/
      schema: http://schema.org/

imports:
      - linkml:types

classes:
    Organization:
      class_uri: schema:Organization
      attributes:
        name:
          slot_uri: schema:name
          range: string
    Address:
      class_uri: schema:PostalAddress
      attributes:
        street:
          range: string
          slot_uri: schema:street
        city:
          range: string
          slot_uri: schema:city
        postal_code:
          range: string
          slot_uri: schema:postalCode
    Person:
      tree_root: true
      class_uri: schema:Person
      attributes:
        name:
          slot_uri: schema:name
          range: string
          description: the name of a person
          required: true
          annotations:
            - tag: options
              value:
                hidden: false
            - template: " "
            - tag: watch
              value: 
                first_name: first_name
                last_name: last_name

        first_name:
          range: string
        last_name:
          range: string
        birth_date:
          slot_uri: schema:birthDate
          range: date
          recommended: true
          annotations: 
            title: Birth date
        address:
          slot_uri: schema:address
          range: Address
        employer:
          name: employer
          range: Organization
          inlined: false
          inlined_as_list: false

produces an OO-LD schema (JSON-LD context + JSON Schema with additional annotation for userinterface generation like, e.g. options and template)

Person.oold.yaml

'@context':
  xsd: http://www.w3.org/2001/XMLSchema#
  Person:
    '@id': schema:Person
  linkml: https://w3id.org/linkml/
  schema: http://schema.org/
  '@vocab': https://example.org/Person/
  city:
    '@id': schema:city
  postal_code:
    '@id': schema:postalCode
  street:
    '@id': schema:street
  name:
    '@id': schema:name
  address:
    '@type': '@id'
    '@id': schema:address
  birth_date:
    '@type': xsd:date
    '@id': schema:birthDate
  employer:
    '@type': '@id'
    '@id': employer
  first_name:
    '@id': first_name
  last_name:
    '@id': last_name
  Address:
    '@id': schema:PostalAddress
  Organization:
    '@id': schema:Organization
$schema: https://json-schema.org/draft/2020-12/schema
$id: https://example.org/Person/
metamodel_version: 1.7.0
version: null
title: Person
type: object
additionalProperties: true
$defs:
  Organization:
    type: object
    additionalProperties: false
    description: ''
    properties:
      name:
        type: string
    title: Organization
  Address:
    type: object
    additionalProperties: false
    description: ''
    properties:
      street:
        type: string
      city:
        type: string
      postal_code:
        type: string
    title: Address
  Person:
    type: object
    additionalProperties: false
    description: ''
    properties:
      name:
        type: string
        description: the name of a person
        options:
          hidden: false
        template: ' '
        watch:
          first_name: first_name
          last_name: last_name
      first_name:
        type: string
      last_name:
        type: string
      birth_date:
        type: string
        format: date
        title: Birth date
      address:
        $ref: '#/$defs/Address'
      employer:
        $ref: '#/$defs/Organization'
    required:
    - name
    title: Person
description: ''
properties:
  name:
    type: string
    description: the name of a person
    options:
      hidden: false
    template: ' '
    watch:
      first_name: first_name
      last_name: last_name
  first_name:
    type: string
  last_name:
    type: string
  birth_date:
    type: string
    format: date
    title: Birth date
  address:
    $ref: '#/$defs/Address'
  employer:
    $ref: '#/$defs/Organization'
required:
- name

which can be copy-pasted into OO-LD playground

to get an auto-generated userinterface (based on https://github.com/json-editor/json-editor):

grafik

Populating x-oold-range in combination with a proper backend allows user to created non-inlined objects on the fly or link (= store the IRI) to existing ones (see https://opensemantic.world / https://demo.open-semantic-lab.org):

grafik

Minor unsolved issues:

annotations with object-values cannot be written in compact form, only with additional value-key in between
some information already encoded in LinkML is not yet part of the generated JSON Schema (e.g. default values)