Part 5: Using Python dataclasses
If you are not a developer, you can skip this section.
If you are a developer and favor a language other than python, you may still be interested in this section. The use of generated code is an optional but convenient part of LinkML. We are actively adding support for other languages.
Generating a Python datamodel
For illustration, we will take the schema we developed in the last section:
id: https://w3id.org/linkml/examples/personinfo name: personinfo prefixes: ## Note are adding 3 new ones here linkml: https://w3id.org/linkml/ schema: http://schema.org/ personinfo: https://w3id.org/linkml/examples/personinfo/ ORCID: https://orcid.org/ imports: - linkml:types default_range: string classes: Person: class_uri: schema:Person ## reuse schema.org vocabulary attributes: id: identifier: true full_name: required: true description: name of the person slot_uri: schema:name ## reuse schema.org vocabulary aliases: multivalued: true description: other names for the person phone: pattern: "^[\\d\\(\\)\\-]+$" slot_uri: schema:telephone ## reuse schema.org vocabulary age: range: integer minimum_value: 0 maximum_value: 200 id_prefixes: - ORCID Container: attributes: persons: multivalued: true inlined_as_list: true range: Person
We can use a script that is distributed with LinkML to generate a python dataclasses model:
gen-python personinfo.yaml > personinfo.py
This creates a python datamodel:
@dataclass class Person(NamedThing): """ A person (alive, dead, undead, or fictional). """ id: Union[str, PersonId] = None full_name: Optional[str] = None ...
Note you don’t need to directly view the python - but your favorite IDE should be able to autocomplete and type check as expected
You can now write code like:
from personinfo import Person p1 = Person(id='ORCID:9876', full_name='Lex Luthor') print(p1)
Person(id='ORCID:9876', full_name='Lex Luthor', aliases=, phone=None, age=None)
Hurray! Perhaps this is not very impressive in itself, but having an object model that is guaranteed to be in sync with your data model can help with productivity and robustness of code.
LinkML also includes a more lightweight Python object model maker for generating Pydantic datamodels
We also provide a generator for creating SQL Alchemy models
We are gradually adding support for other languages
For a full list of generators see generators
Next we will look at the enumerations feature of LinkML