Type Bridge

type-bridge Python ORM for TypeDB

type-bridge is a Pythonic ORM for TypeDB that provides type-safe abstractions over TypeQL.

Quick Start

from type_bridge import (
    Entity, Relation, Role, String, Integer, Double, Boolean,
    Flag, Key, Unique, Card, TypeFlags, Database, SchemaManager
)

# 1. Define attribute types (reusable across entities)
class Name(String):
    pass

class Email(String):
    pass

class Age(Integer):
    pass

# 2. Define entity with ownership
class Person(Entity):
    flags = TypeFlags(name="person")
    name: Name = Flag(Key)           # Primary key
    email: Email = Flag(Unique)      # Unique constraint
    age: Age | None = None           # Optional field

# 3. Connect and sync schema
db = Database(address="localhost:1729", database="mydb")
with db:
    db.create_database()
    schema = SchemaManager(db)
    schema.register(Person)
    schema.sync_schema()

    # 4. CRUD operations
    manager = Person.manager(db)
    alice = Person(name=Name("Alice"), email=Email("alice@example.com"), age=Age(30))
    manager.insert(alice)

Defining Models

Attribute Types

Attributes are independent types that can be owned by entities and relations.

from type_bridge import String, Integer, Double, Boolean, DateTime, Date, Duration, Decimal

# Simple attributes (inherit from value types)
class Name(String):
    pass

class Score(Double):
    pass

class IsActive(Boolean):
    pass

class CreatedAt(DateTime):
    pass

# Attribute with custom TypeDB name
from type_bridge import AttributeFlags

class PersonEmail(String):
    flags = AttributeFlags(name="email")  # TypeDB name: "email", not "person_email"

Entities

from type_bridge import Entity, Flag, Key, Unique, Card, TypeFlags

class Person(Entity):
    flags = TypeFlags(name="person")

    # Key attribute (required, unique identifier)
    person_id: PersonId = Flag(Key)

    # Unique attribute (unique but not primary key)
    email: Email = Flag(Unique)

    # Required attribute (no default)
    name: Name

    # Optional attribute
    age: Age | None = None

    # Multi-valued attribute (list)
    tags: list[Tag] = Flag(Card(min=0))

# Abstract entity (cannot be instantiated, only inherited)
class Artifact(Entity):
    flags = TypeFlags(name="artifact", abstract=True)
    name: Name

# Inherited entity
class Document(Artifact):
    flags = TypeFlags(name="document")
    content: Content

Relations

from type_bridge import Relation, Role, TypeFlags

class Employment(Relation):
    flags = TypeFlags(name="employment")

    # Define roles with their player types
    employee: Role[Person] = Role("employee", Person)
    employer: Role[Company] = Role("employer", Company)

    # Relations can own attributes too
    start_date: StartDate
    end_date: EndDate | None = None

# Entities must declare they play roles
class Person(Entity):
    flags = TypeFlags(name="person")
    name: Name = Flag(Key)
    # ... plays employment:employee (implicit from Role definition)

class Company(Entity):
    flags = TypeFlags(name="company")
    name: Name = Flag(Key)

Role Cardinality

For relations where the same role has multiple players of the same type:

from type_bridge import Relation, Role, Card, TypeFlags

# Exactly 2 Memory entities playing the same role
class IsSimilarTo(Relation):
    flags = TypeFlags(name="is_similar_to")
    similar_memory: Role[Memory] = Role("similar_memory", Memory, Card(2, 2))

# Generates: relation is_similar_to, relates similar_memory @card(2..2);

Card variations for roles:

Creating instances with multiple role players:

memory1 = Memory(content=Content("First memory"))
memory2 = Memory(content=Content("Second memory"))

# Pass a list for roles with multiple players
similarity = IsSimilarTo(similar_memory=[memory1, memory2])
manager.insert(similarity)

CRUD Operations

Entity Manager

# Get manager for an entity type
manager = Person.manager(db)

# Insert
alice = Person(name=Name("Alice"), email=Email("alice@example.com"))
manager.insert(alice)

# Get all
all_persons = manager.all()

# Filter with dict
adults = manager.filter(age=Age(18)).all()

# Filter with expressions
seniors = manager.filter(Person.age.gte(Age(65))).all()

# Get first match
first = manager.filter(name=Name("Alice")).first()

# Count
total = manager.filter().count()

# Update (updates in-place)
alice.age = Age(31)
manager.update(alice)

# Delete
manager.delete(alice)

# Put (upsert - insert or update by key)
manager.put(Person(name=Name("Bob"), email=Email("bob@example.com")))

Relation Manager

# Get manager for relation type
emp_manager = Employment.manager(db)

# Insert relation (entities must exist)
alice = Person(name=Name("Alice"))
acme = Company(name=Name("Acme"))
employment = Employment(
    employee=alice,
    employer=acme,
    start_date=StartDate(date(2024, 1, 15))
)
emp_manager.insert(employment)

# Query relations
acme_employees = emp_manager.filter(employer=acme).all()

Transactions

# Explicit transaction for multiple operations
with db.transaction("write") as tx:
    person_mgr = Person.manager(tx)
    company_mgr = Company.manager(tx)

    alice = Person(name=Name("Alice"))
    acme = Company(name=Name("Acme"))

    person_mgr.insert(alice)
    company_mgr.insert(acme)
    # Auto-commits on exit, rolls back on exception

Query Expressions

Comparison Expressions

# Available on all attribute field references
Person.age.eq(Age(30))      # ==
Person.age.neq(Age(30))     # !=
Person.age.gt(Age(18))      # >
Person.age.gte(Age(18))     # >=
Person.age.lt(Age(65))      # <
Person.age.lte(Age(65))     # <=

# String-specific
Person.name.contains("Ali")
Person.name.like("^A.*")    # Regex match

# Chaining filters (AND)
manager.filter(Person.age.gte(Age(18))).filter(Person.age.lt(Age(65))).all()

Boolean Expressions

from type_bridge.expressions import BooleanExpr

# OR
manager.filter(
    BooleanExpr.or_(
        Person.name.eq(Name("Alice")),
        Person.name.eq(Name("Bob"))
    )
).all()

# NOT
manager.filter(
    BooleanExpr.not_(Person.status.eq(Status("inactive")))
).all()

Aggregations

# Single aggregation
result = manager.filter().aggregate(Person.age.avg())
avg_age = result["avg_age"]

# Multiple aggregations
result = manager.filter().aggregate(
    Person.age.avg(),
    Person.salary.sum(),
    Person.score.max()
)

# Available: .avg(), .sum(), .min(), .max(), .count(), .std(), .median()

Group By

# Group by single field
result = manager.group_by(Person.department).aggregate(
    Person.salary.avg(),
    Person.age.avg()
)
# Returns: {"Engineering": {"avg_salary": 95000, "avg_age": 32}, ...}

# Group by multiple fields
result = manager.group_by(Person.department, Person.level).aggregate(
    Person.salary.avg()
)

Pagination

# Limit and offset
page = manager.filter().limit(10).offset(20).all()

# First N results
top_5 = manager.filter(Person.score.gte(Score(90))).limit(5).all()

Schema Management

from type_bridge import SchemaManager

schema = SchemaManager(db)

# Register models
schema.register(Person, Company, Employment)

# Sync schema (creates types in TypeDB)
schema.sync_schema()

# Force sync (recreates even if exists)
schema.sync_schema(force=True)

# Get current schema
current = schema.get_schema()

# Compare schemas
from type_bridge import SchemaDiff
diff = SchemaDiff.compare(old_schema, new_schema)

Built-in Functions (TypeDB 3.8+)

from type_bridge.expressions import iid, label

# These are used internally by type-bridge for IID and type fetching
# The library handles this automatically in manager operations

# Direct usage in custom queries:
expr = iid("$e")       # Generates: iid($e)
expr = label("$t")     # Generates: label($t)

# IMPORTANT: label() only works on TYPE variables, not instance variables
# Pattern: $e isa! $t; $t sub person; ... label($t)

Common Patterns

Get by IID

# Fetch entity by internal ID (fast direct lookup)
person = manager.get_by_iid("0x1e00000000000000000123")

Polymorphic Queries

# Query abstract type to get all subtypes
class Animal(Entity):
    flags = TypeFlags(name="animal", abstract=True)

class Dog(Animal):
    flags = TypeFlags(name="dog")

class Cat(Animal):
    flags = TypeFlags(name="cat")

# Gets both Dogs and Cats
animal_manager = Animal.manager(db)
all_animals = animal_manager.all()

Polymorphic Role Players

When a relation role uses an abstract type, queried role players are resolved to their concrete types:

# Abstract base
class Profile(Entity):
    flags = TypeFlags(name="profile", abstract=True)
    profile_id: ProfileId = Flag(Key)

# Concrete subtypes
class Person(Profile):
    flags = TypeFlags(name="person")
    email: Email | None = None

class Organization(Profile):
    flags = TypeFlags(name="org")
    website: Website | None = None

# Relation with abstract role type
class Authorship(Relation):
    flags = TypeFlags(name="authorship")
    author: Role[Profile] = Role("author", Profile)  # Abstract!
    post: Role[Post] = Role("post", Post)

# Query - role players resolved to concrete types
authorships = Authorship.manager(db).all()
for auth in authorships:
    # author is Person or Organization, NOT abstract Profile
    if isinstance(auth.author, Person):
        print(f"Person: {auth.author.email}")
    elif isinstance(auth.author, Organization):
        print(f"Org: {auth.author.website}")

Serialization

# Convert to dict
person_dict = person.to_dict()

# Create from dict
person = Person.from_dict(person_dict)

Raw Queries

# Execute raw TypeQL
results = db.execute_query("""
    match $p isa person, has name $n;
    fetch { "name": $n };
""", "read")

Cardinality Flags

from type_bridge import Flag, Key, Unique, Card

class Person(Entity):
    # Key: exactly one, unique identifier
    id: PersonId = Flag(Key)

    # Unique: exactly one, unique but not key
    email: Email = Flag(Unique)

    # Card(0..1): optional (0 or 1)
    nickname: Nickname | None = Flag(Card(max=1))

    # Card(1..): at least one required
    phone: Phone = Flag(Card(min=1))

    # Card(0..): zero or more (default for lists)
    tags: list[Tag] = Flag(Card(min=0))

    # Card(2..5): between 2 and 5
    references: list[Reference] = Flag(Card(min=2, max=5))

Important Notes

1. Keyword-only arguments: All Entity/Relation constructors require keyword arguments

   # Correct
   Person(name=Name("Alice"), age=Age(30))
   
   # Wrong - will fail
   Person(Name("Alice"), Age(30))
   

2. Attribute instances: Always wrap values in attribute types

   # Correct
   person.age = Age(31)
   
   # Wrong
   person.age = 31
   

3. TypeFlags required: Entities and Relations need flags = TypeFlags(name="...")

4. Connection management: Use context managers or explicit connect/close

   with Database(...) as db:
       # operations
   # Auto-closed
   

5. Schema sync before data: Always sync schema before inserting data

6. Role player matching: Relation CRUD operations identify role players using:

   • IID (preferred): If the entity has _iid set (from being fetched from DB), uses fast IID matching
   • Key attributes (fallback): If no IID, uses Flag(Key) attributes to identify the entity
   • Error: If neither is available, raises ValueError with clear guidance

   # Pattern 1: Fetch entities first (uses IID matching - faster)
   alice = person_manager.filter(name=Name("Alice")).first()  # alice._iid is set
   emp = Employment(employee=alice, employer=company)
   emp_manager.insert(emp)  # Uses alice._iid for matching
   
   # Pattern 2: Create stub entities (uses key attribute matching)
   alice = Person(name=Name("Alice"))  # No _iid
   emp = Employment(employee=alice, employer=company)
   emp_manager.insert(emp)  # Uses name (key attr) for matching
   

7. Transaction types:

   • "read": For queries (no commit needed)
   • "write": For insert/update/delete (auto-commits)
   • "schema": For schema changes (auto-commits)

Code Generator

Generate Python models from TypeDB schema files instead of writing them manually.

CLI Usage

# Generate models from schema
python -m type_bridge.generator schema.tql -o ./myapp/models/

# With Pydantic API DTOs
python -m type_bridge.generator schema.tql -o ./myapp/models/ --dto

# With custom DTO configuration
python -m type_bridge.generator schema.tql -o ./myapp/models/ --dto --dto-config myapp.config:dto_config

Programmatic Usage

from type_bridge.generator import generate_models

# Basic generation
generate_models("schema.tql", "./myapp/models/")

# With API DTOs
generate_models("schema.tql", "./myapp/models/", generate_dto=True)

# With custom DTO config
from type_bridge.generator import DTOConfig, BaseClassConfig

config = DTOConfig(
    exclude_entities=["internal_counter"],
    entity_union_name="GraphNode",
)
generate_models("schema.tql", "./myapp/models/", generate_dto=True, dto_config=config)

Generated Files

myapp/models/
├── __init__.py      # Package exports
├── attributes.py    # Attribute classes
├── entities.py      # Entity classes
├── relations.py     # Relation classes
├── registry.py      # Schema metadata
├── api_dto.py       # Pydantic DTOs (if --dto)
└── schema.tql       # Copy of schema

API DTOs (Pydantic)

Generate Pydantic models for REST APIs from your TypeDB schema.

Generated Structure

# Entity DTOs
class PersonOut(BaseDTOOut): ...    # Response with 'iid' field
class PersonCreate(BaseDTOCreate): ...  # Create payload
class PersonPatch(BaseDTOPatch): ...    # Partial update

# Relation DTOs
class FriendshipOut(BaseRelationOut): ...
class FriendshipCreate(BaseRelationCreate): ...

# Union types (discriminated by 'type' field)
EntityOut = Annotated[Union[PersonOut, ...], Field(discriminator="type")]

DTOConfig Options

from type_bridge.generator import (
    DTOConfig, BaseClassConfig, ValidatorConfig, FieldSyncConfig,
    FieldOverride, EntityFieldOverride,
)

config = DTOConfig(
    # Exclude internal entities
    exclude_entities=["display_id_counter", "schema_status"],

    # Rename IID field to 'id'
    iid_field_name="id",

    # Custom union names
    entity_union_name="GraphNode",
    relation_union_name="GraphRelation",

    # Custom validators with regex
    validators=[
        ValidatorConfig(name="DisplayId", pattern=r"^[A-Z]{1,5}-\d+$"),
    ],

    # Custom base class for entity hierarchies
    base_classes=[
        BaseClassConfig(
            source_entity="artifact",
            base_name="BaseArtifact",
            inherited_attrs=["display_id", "name", "description"],
            extra_fields={"version": "int | None = None"},
            field_syncs=[FieldSyncConfig("description", "content")],
            # Make @key field optional on Create (server auto-generates)
            create_field_overrides={
                "display_id": FieldOverride(required=False),
            },
        ),
    ],

    # Per-entity field overrides (target specific entity + field + variant)
    entity_field_overrides=[
        EntityFieldOverride(entity="task", field="status", variant="create",
                            required=False, default="'proposed'"),
    ],

    # Composite entities with skip_variants and extra_fields_out
    composite_entities=[
        CompositeEntityConfig(
            name="GraphNode",
            include_entities=["task", "epic"],
            skip_variants={"out", "create", "patch"},  # Only generate type enum
            extra_fields_out={"id": "str"},  # Required on Out, optional elsewhere
        ),
    ],

    # Custom code injection
    preamble="...",  # After imports
    relation_preamble="...",  # In relation section

    # Custom relation structure
    skip_relation_output=True,  # Skip relation Out classes
    relation_create_base_class="BaseRelationCreate",  # Custom base
)

Usage in FastAPI

from myapp.models.api_dto import PersonOut, PersonCreate, EntityOut

@app.post("/persons", response_model=PersonOut)
def create_person(data: PersonCreate) -> PersonOut:
    person = Person(name=Name(data.name))
    manager.insert(person)
    return PersonOut(iid=person.iid, name=data.name, type="person")

@app.get("/entities/{id}", response_model=EntityOut)
def get_entity(id: str) -> EntityOut:
    # Returns PersonOut, CompanyOut, etc. based on 'type' discriminator
    ...

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