ontosql 0.3.0

Semantic data access for SQL — map ontology-shaped models onto real schemas with explicit OntoMapper bindings (import ontosql)

OntoSQL

Semantic data access for SQL — map ontology-shaped models onto real database schemas and write CRUD in Python, not RDF.

Real databases are not one table per ontology class. OntoSQL separates physical SQLModel tables from semantic Pydantic entities and connects them with an explicit mapper. Application code uses semantic types; OntoSQL compiles SQL on the backend. RDF export uses TripleModel; graph-native apps can pair OntoSQL with SparqlModel — see Ecosystem.

pip install ontosql
pip install "ontosql[fastapi]"   # OntoRouter + content negotiation
pip install "ontosql[jsonld]"    # optional JSON-LD compact/frame (PyLD)
pip install "ontosql[sparql]"    # optional SparqlModel for graph sync / hybrid apps

Quick start

1. Physical models (database truth)

from sqlmodel import Field, SQLModel


class OrgRow(SQLModel, table=True):
    __tablename__ = "orgs"
    id: int | None = Field(default=None, primary_key=True)
    name: str


class PersonRow(SQLModel, table=True):
    __tablename__ = "people"
    id: int | None = Field(default=None, primary_key=True)
    name: str
    org_id: int | None = Field(default=None, foreign_key="orgs.id")

2. Semantic models (what your app uses)

from ontosql import OntoModel, onto_property


class Organization(OntoModel):
    type_iri = "schema:Organization"
    iri_template = "https://data.example.org/org/{id}"

    id: int
    name: str = onto_property("schema:name")


class Person(OntoModel):
    type_iri = "schema:Person"
    iri_template = "https://data.example.org/person/{id}"

    id: int
    name: str = onto_property("schema:name")
    employer: Organization | None = onto_property("schema:worksFor")

3. Maps (explicit SQL bindings)

from ontosql import Map, OntoMapper


class OrganizationMap(OntoMapper[Organization]):
    entity = Organization
    id = Map(OrgRow.id)
    name = Map(OrgRow.name, property="schema:name")


class PersonMap(OntoMapper[Person]):
    entity = Person
    id = Map(PersonRow.id)
    name = Map(PersonRow.name, property="schema:name")
    employer = Map.nested(
        Organization,
        join=(PersonRow.org_id == OrgRow.id),
        target=OrgRow,
        nested_map=OrganizationMap,
        property="schema:worksFor",
        fk_column=PersonRow.org_id,
    )

4. Session (CRUD)

from ontosql import OntoSession, paginate

with OntoSession(engine, maps=[PersonMap, OrganizationMap]) as session:
    ada = session.get(Person, id=1)
    team = session.find(Person, where=Person.employer.name.startswith("Analytical"))
    page = paginate(session, Person, limit=20, offset=0)

    new_person = session.save(Person.model_construct(name="Grace Hopper", id=None))
    new_person.name = "Grace M. Hopper"
    session.save(new_person)
    session.delete(new_person)

Async sessions use AsyncOntoSession with the same API (async with, await session.get, await session.find).

5. Export

print(ada.to_rdf(format="turtle"))
print(ada.to_jsonld())

Export walks OntoModel + onto_property metadata and serializes via TripleModel (pyoxigraph). Nested semantic objects become linked RDF resources.

Features

• OntoModel + onto_property — semantic entities with ontology IRIs
• OntoMapper / Map — declarative bindings to columns, joins, and nested entities
• OntoSession / AsyncOntoSession — get, find, save, delete, paginate, identity map
• Semantic queries — nested paths, contains / endswith, OrderBy(desc=True)
• CascadePolicy — explicit nested write behavior on Map.nested
• OntoRouter (ontosql[fastapi]) — auto CRUD routes + content negotiation
• PrefixRegistry — CURIE expansion and JSON-LD @context (CURIE expand via TripleModel)
• Export — to_jsonld() / to_rdf() on semantic instances (TripleModel serializers)
• FastAPI (ontosql[fastapi]) — content negotiation for JSON-LD and RDF payloads
• Ecosystem — TripleModel (core RDF), SparqlModel (optional ontosql[sparql])

FastAPI

from fastapi import FastAPI
from ontosql.fastapi import OntoRouter, onto_session_lifespan

app = FastAPI()
onto_session_lifespan(app, engine, [PersonMap, OrganizationMap])
router = OntoRouter(maps=[PersonMap, OrganizationMap])
router.register(Person)
router.include_in(app)

See examples/person_org_demo.py for CRUD and examples/person_org_api.py for a runnable API.

Documentation

• Architecture
• Ecosystem — OntoSQL, TripleModel, SparqlModel
• Technical specification
• Roadmap
• Project plan
• Dependency assessment
• Changelog

Development

See Releasing for the version publish checklist.

pip install -e ".[dev]"
ruff check src tests
ruff format src tests
ty check
pytest --cov=ontosql --cov-fail-under=100

License

MIT — see LICENSE.