triplemodel 0.3.0

Pydantic TripleModel classes ↔ RDF triples via rdflib (alpha).

TripleModel

Typed Pydantic models for RDF. Declare fields once, get correct triples in and out of rdflib Graph objects — no manual graph.add for every property.

Install	pip install triplemodel
Import	from triplemodel import TripleModel, rdf_field
Docs	triplemodel.readthedocs.io

Person(slug="alice", name="Alice")  →  (ex:alice, foaf:name, "Alice")  →  Person(...)

TripleModel is the mapping layer between Pydantic-shaped domain models and RDF triples: subject IRIs, XSD literals, nested resources, rdf:List, language tags, and graph sync. It is stateless and in-memory today; SparqlModel (sessions, SPARQL, ORM) is planned to build on top — see the ecosystem guide.

0.3.0 is alpha. APIs may change before 1.0. See the changelog and roadmap.

Install

pip install triplemodel

Requirements: Python 3.10+, Pydantic 2, rdflib 7.

Quick start

from triplemodel import TripleModel, rdf_field

FOAF = "http://xmlns.com/foaf/0.1/"

class Person(TripleModel):
    class Rdf:
        namespace = "http://example.org/people/"
        type_uri = f"{FOAF}Person"
        id_field = "slug"

    slug: str
    name: str = rdf_field(f"{FOAF}name")
    age: int | None = rdf_field(f"{FOAF}age", default=None)

alice = Person(slug="alice", name="Alice", age=30)
graph = alice.to_graph()

assert Person.from_graph(graph, alice.subject_uri()) == alice
print(alice.subject_uri())

http://example.org/people/alice

Unmapped fields are ignored on export/import — useful for computed or application-only data.

Features

Area	Capability
Mapping	Nested class Rdf + rdf_field() or Annotated[..., Predicate(...)]
Identity	Subject IRIs from namespace + id_field (percent-encoded ids)
Scalars	str, int, float, bool, date, datetime; IRI-like str → URIRef
Collections	set[T] → multiple objects per predicate; list[T] → ordered rdf:List
Literals	LangString, Lang(), OpaqueLiteral, ResourceRef
Nesting	Child TripleModel with Rdf.embed "iri" or "bnode"
Graph writes	to_graph / sync_to_graph with add, replace, or patch
Namespaces	Rdf.prefixes, CURIE predicates ("foaf:name"), bind_namespaces
Typing	PEP 561 py.typed

Coming later (roadmap): file parse / serialize (0.4), named graphs (0.5), SPARQL helpers (0.6).

list vs set

Annotation	RDF shape
set[str]	Multiple objects on one predicate (unordered)
list[str]	One ordered rdf:List (rdf:first / rdf:rest)

Use set for tags or duplicate predicates; use list when the graph should contain a real RDF list.

Full example

Language tags, RDF lists, and nested blank-node embeds:

from typing import Annotated

from triplemodel import TripleModel, rdf_field, sync_to_graph
from triplemodel.terms.lang import Lang, LangString
from triplemodel.vocab import DC, FOAF

class Address(TripleModel):
    class Rdf:
        namespace = "http://example.org/address/"
        type_uri = "http://example.org/Address"
        id_field = "slug"

    slug: str = "home"
    street: str = rdf_field("http://example.org/street")


class Person(TripleModel):
    class Rdf:
        namespace = "http://example.org/people/"
        type_uri = f"{FOAF}Person"
        id_field = "slug"
        embed = "bnode"
        prefixes = {"foaf": str(FOAF), "dc": str(DC)}

    slug: str
    title: LangString = rdf_field(f"{DC}title")
    nick: list[str] = rdf_field("foaf:nick", default_factory=list)
    address: Address | None = rdf_field("http://example.org/home", default=None)


person = Person(
    slug="alice",
    title=LangString("Alice's profile", "en"),
    nick=["Al", "Alice"],
    address=Address(street="1 Main St"),
)
graph = person.to_graph()

person.nick = ["Alice"]
sync_to_graph(person, graph, mode="replace")
again = Person.from_graph(graph, person.subject_uri())
print(again.nick)

['Alice']

Runnable version: examples/exit_criteria_03.py (same models; see also examples/doc/snippets/).

How mapping works

class Rdf — resource metadata

Attribute	Role
namespace	Base IRI; subject = namespace + encoded id_field value
type_uri	rdf:type on export; filter for all_from_graph()
id_field	Python field whose value becomes the subject id segment
embed	"iri" (default) or "bnode" for nested models
prefixes	CURIE map → Graph.bind on new graphs
graph_mode	Default to_graph mode when mode= is omitted
blank_node_policy	"fresh" or "stable" nested bnodes
skolemize_export / skolemize_import	Blank-node skolemization defaults

Override the subject per call with uri= when the IRI still lives under namespace:

graph = alice.to_graph(uri="http://example.org/people/alice")

Helpers: subject_base(), id_from_subject_uri().

Fields → predicates

name: str = rdf_field("foaf:name")  # with Rdf.prefixes

from typing import Annotated
from triplemodel import Predicate

title: Annotated[str, Predicate("http://purl.org/dc/terms/title")]
title_fr: Annotated[str, Predicate(f"{DC}title"), Lang("fr")]

Subclasses inherit a parent Rdf when the child does not define one. A child class Rdf: replaces the parent config entirely — never use an empty nested Rdf on a subclass.

Scalar → RDF (export)

Python	RDF
str (plain)	xsd:string
str with URI scheme (http:, urn:, …)	URIRef
int, float, bool, date, datetime	XSD literal
LangString, ResourceRef, OpaqueLiteral	matching literal / IRI

Register custom types with register_literal_type and LiteralRegistry.

Updating an existing graph

Default to_graph() uses mode="add" — it only appends. To remove triples when fields are cleared, use sync modes:

from triplemodel import sync_to_graph

sync_to_graph(person, graph, mode="replace")  # replace all owned triples for this subject
sync_to_graph(person, graph, mode="patch")    # per-predicate replace; lighter touch

replace clears nested IRI children and list heads before re-export; patch updates predicates present in the model and clears empty fields (including on nested resources). See the updating graphs guide.

API overview

Instance & class methods

Method	Description
subject_uri(uri=None)	Subject IRI for this instance
to_triples(uri=None)	(subject, predicate, object) rows
to_graph(graph=None, uri=None, mode="add", skolemize=None)	Serialize into a Graph
sync_to_graph(graph, uri=None, mode="replace", skolemize=None)	Sync owned triples in-place
from_graph(graph, uri, ...)	Load one resource
all_from_graph(graph, type_uri=None, ...)	Load all resources of this type
rdf_config()	Resolved RdfConfig

Common imports

from triplemodel import (
    TripleModel,
    rdf_field,
    Predicate,
    GraphMode,
    sync_to_graph,
    models_to_graph,
    merge_graphs,
    expand_curie,
    bind_namespaces,
    LangString,
    Lang,
    ResourceRef,
    OpaqueLiteral,
    RDF,
    XSD,
)

Full API: Read the Docs API reference.

More examples

Batch export

from rdflib import Graph
from triplemodel import models_to_graph

graph = models_to_graph([alice, bob])
models_to_graph([alice, bob], Graph())  # merge into existing graph

Encoded subject ids

bob = Person(slug="bob jones", name="Bob")
print(bob.subject_uri())

http://example.org/people/bob%20jones

Multiple tags on one predicate — use set[str] = rdf_field("foaf:topic", default_factory=set).

Runnable scripts: examples/exit_criteria_03.py, examples/readme_examples.py, and examples/doc/snippets/.

TripleModel vs SparqlModel

You need	Package
Pydantic ↔ triples on an in-memory Graph	triplemodel
File I/O, datasets, SPARQL sessions, cascade put	SparqlModel (planned TripleModel dependency)

Known limitations

• In-memory only until 0.4 (parse / serialize on the roadmap).
• BNode embed is experimental; prefer embed="iri" for stable linking.
• Collections — list[T] / set[T] require scalar T; list[TripleModel] is not supported.
• BNode subjects are skipped by all_from_graph().
• Default add mode does not remove stale triples — use sync_to_graph or mode="replace".

Details: user guides · RDF lists & lang.

Development

git clone https://github.com/eddiethedean/triplemodel.git && cd triplemodel
python -m venv .venv && source .venv/bin/activate
pip install -e ".[dev]"
pytest
ruff format src tests && ruff check src tests
ty check src tests
PYTHONPATH=src python examples/exit_criteria_03.py
PYTHONPATH=src:. python examples/doc/regenerate_outputs.py  # refresh doc output files

CI: Python 3.10–3.13; tests/test_doc_examples.py runs every snippet under examples/doc/snippets/. Release process: RELEASING.md.

Documentation

Resource	Link
User guides	guides index
API reference	api
Changelog	CHANGELOG.md
Roadmap	docs/ROADMAP.md
Ecosystem	docs/ECOSYSTEM.md

License

MIT — see LICENSE.