Copyright (c) 2026 Microsoft Corporation. - Graphrag

python

# Copyright (c) 2026 Microsoft Corporation.
# Licensed under the MIT License.

Factory module example

The Factory class provides a flexible dependency injection pattern that can register and create instances of classes implementing a common interface using string-based strategies. It supports both transient scope (creates new instances on each request) and singleton scope (returns the same instance after first creation).

python

from abc import ABC, abstractmethod

from graphrag_common.factory import Factory


class SampleABC(ABC):
    """Abstract base class for sample implementations."""

    @abstractmethod
    def get_value(self) -> str:
        """Return the value of the sample implementation."""
        msg = "Subclasses must implement the get_value method."
        raise NotImplementedError(msg)


class ConcreteClass(SampleABC):
    """A concrete implementation of SampleABC."""

    def __init__(self, value: str):
        print(f"Creating ConcreteClass with value: {value}")
        self._value = value

    def get_value(self) -> str:
        """Return the value of the sample implementation."""
        return self._value


class SampleFactory(Factory[SampleABC]):
    """A Factory for SampleABC classes."""


factory = SampleFactory()

python

# Registering transient services
# A new one is created for every request
factory.register("some_strategy", ConcreteClass)

trans1 = factory.create("some_strategy", {"value": "test1"})
trans2 = factory.create("some_strategy", {"value": "test2"})

print(f"Value from trans1: {trans1.get_value()}")  # Output: test1
print(f"Value from trans2: {trans2.get_value()}")  # Output: test2

assert trans1 is not trans2
assert trans1.get_value() == "test1"
assert trans2.get_value() == "test2"

python

# Registering singleton services
# After first creation, the same one is returned every time
factory.register("some_other_strategy", ConcreteClass, scope="singleton")

single1 = factory.create("some_other_strategy", {"value": "singleton"})
single2 = factory.create("some_other_strategy", {"value": "ignored"})

print(f"Value from single1: {single1.get_value()}")  # Output: singleton
print(f"Value from single2: {single2.get_value()}")  # Output: singleton

assert single1 is not single2
assert single1.get_value() == "singleton"
assert single2.get_value() == "ignored"