py-spring-core 0.3.7

PySpring is a Python web framework inspired by Spring Boot, combining FastAPI, and Pydantic for building scalable web applications with auto dependency injection, configuration management, and a web server.

PySpring Core

PySpring is a Python framework inspired by Spring Boot. It combines FastAPI for the web layer and Pydantic for data validation, providing a structured approach to building scalable web applications with automatic dependency injection, configuration management, component lifecycle hooks, event-driven architecture, and a built-in web server.

Key Features

• IoC Container & Dependency Injection - Automatic dependency injection based on type annotations, supporting Component, BeanCollection, Properties, and qualifier-based resolution via Annotated[T, 'qualifier'].

• Component Lifecycle - Components support Singleton and Prototype scopes, with post_construct() and pre_destroy() lifecycle hooks.

• REST Controllers - Declarative route definition using @GetMapping, @PostMapping, @PutMapping, @DeleteMapping, and @PatchMapping decorators with full FastAPI parameter support.

• Properties Management - Type-safe configuration via Pydantic-based Properties classes, loaded from a JSON properties file and automatically injected into components.

• Bean Collections - Factory-style bean registration using BeanCollection classes with create_* methods and return type annotations.

• Middleware Support - Custom middleware via the Middleware base class and MiddlewareConfiguration for controlling registration order through MiddlewareRegistry.

• Event System - Publish/subscribe event architecture using ApplicationEventPublisher, ApplicationEvent, and the @EventListener decorator.

• Graceful Shutdown - Configurable graceful shutdown handling with GracefulShutdownHandler, supporting SIGINT/SIGTERM signals with timeout management.

• Exception Handlers - Global exception handling with the @ExceptionHandler decorator.

• Starter Modules - Extensible plugin system via PySpringStarter, supporting manual registration and auto-discovery through pyspring.starters entry points.

• Logging - Integrated Loguru-based logging with configurable log level, rotation, retention, file output, and JSON format support.

Project Structure

my-pyspring-app/
├── src/                            # Application source code (configurable)
│   ├── controllers/
│   ├── components/
│   ├── properties/
│   └── ...
├── app-config.json                 # Application configuration
├── application-properties.json     # Application properties
└── main.py                        # Application entry point

Getting Started

Prerequisites

• Python >= 3.11, < 3.13

Installation

pip install py-spring-core

Configuration

Create an app-config.json:

{
    "app_src_target_dir": "./src",
    "server_config": {
        "host": "0.0.0.0",
        "port": 8080,
        "enabled": true
    },
    "properties_file_path": "./application-properties.json",
    "loguru_config": {
        "log_file_path": "./logs/app.log",
        "log_level": "DEBUG"
    },
    "shutdown_config": {
        "timeout_seconds": 30.0,
        "enabled": true
    }
}

Create an application-properties.json for your application properties:

{
    "database": {
        "host": "localhost",
        "port": 5432,
        "name": "mydb"
    }
}

Application Entry Point

from py_spring_core import PySpringApplication

def main():
    app = PySpringApplication("./app-config.json")
    app.run()

if __name__ == "__main__":
    main()

Defining a Component

from py_spring_core import Component

class UserService(Component):
    def post_construct(self):
        # Called after dependency injection
        ...

    def pre_destroy(self):
        # Called during shutdown
        ...

    def get_user(self, user_id: int) -> dict:
        return {"id": user_id, "name": "Alice"}

Defining Properties

from py_spring_core import Properties

class DatabaseProperties(Properties):
    __key__ = "database"

    host: str
    port: int
    name: str

Defining a REST Controller

from py_spring_core import RestController, GetMapping, PostMapping

class UserController(RestController):
    class Config:
        prefix = "/api/users"

    # Dependencies are injected automatically by type annotation
    user_service: UserService

    @GetMapping("/{user_id}")
    def get_user(self, user_id: int):
        return self.user_service.get_user(user_id)

    @PostMapping("/")
    def create_user(self, name: str):
        return {"name": name}

Defining a Bean Collection

from py_spring_core import BeanCollection

class AppBeans(BeanCollection):
    def create_http_client(self) -> HttpClient:
        return HttpClient(timeout=30)

Using the Event System

from py_spring_core import (
    Component, ApplicationEvent, ApplicationEventPublisher, EventListener
)

class UserCreatedEvent(ApplicationEvent):
    user_id: int
    username: str

class NotificationService(Component):
    @EventListener(UserCreatedEvent)
    def on_user_created(self, event: UserCreatedEvent):
        print(f"User created: {event.username}")

class UserService(Component):
    event_publisher: ApplicationEventPublisher

    def create_user(self, username: str):
        self.event_publisher.publish(UserCreatedEvent(user_id=1, username=username))

Using Middleware

from fastapi import Request, Response
from py_spring_core import Middleware, MiddlewareConfiguration, MiddlewareRegistry

class AuthMiddleware(Middleware):
    def should_skip(self, request: Request) -> bool:
        return request.url.path == "/health"

    async def process_request(self, request: Request) -> Response | None:
        token = request.headers.get("Authorization")
        if not token:
            return Response(status_code=401, content="Unauthorized")
        return None  # Continue to next middleware/route

class AppMiddlewareConfig(MiddlewareConfiguration):
    def configure_middlewares(self, registry: MiddlewareRegistry):
        registry.add_middleware(AuthMiddleware)

Using Starters

from py_spring_core import PySpringStarter, PySpringApplication

class MyStarter(PySpringStarter):
    def on_configure(self):
        self.component_classes.append(MyComponent)
        self.properties_classes.append(MyProperties)

    def on_initialized(self):
        # Called after IoC container is built
        ...

    def on_destroy(self):
        # Called during shutdown
        ...

# Manual registration
app = PySpringApplication("./app-config.json", starters=[MyStarter()])
app.run()

Component Scopes & Qualifiers

from typing import Annotated
from py_spring_core import Component, ComponentScope

class TransientService(Component):
    class Config:
        scope = ComponentScope.Prototype

class PrimaryCache(Component):
    class Config:
        name = "redis_cache"

class MyService(Component):
    # Qualifier-based injection
    cache: Annotated[CacheBase, "redis_cache"]

Graceful Shutdown

from py_spring_core import GracefulShutdownHandler, ShutdownType

class AppShutdownHandler(GracefulShutdownHandler):
    def on_shutdown(self, shutdown_type: ShutdownType):
        print(f"Shutting down: {shutdown_type}")

    def on_timeout(self):
        print("Shutdown timed out")

    def on_error(self, error: Exception):
        print(f"Shutdown error: {error}")

Configuration Reference

app-config.json

Field	Type	Description
app_src_target_dir	str	Directory containing application source code
server_config.host	str	Server host address
server_config.port	int	Server port number
server_config.enabled	bool	Whether to start the web server (default: true)
exclude_file_patterns	list[str]	Regex patterns for files to exclude from scanning (default: [".*/models\\.py$"])
properties_file_path	str	Path to the properties JSON file
loguru_config.log_file_path	str | null	Log file path (set null to disable file logging)
loguru_config.log_level	str	Log level: TRACE, DEBUG, INFO, SUCCESS, WARNING, ERROR, CRITICAL
loguru_config.log_rotation	str | null	Log rotation interval (e.g. "1 day")
loguru_config.log_retention	str | null	Log retention period (e.g. "7 days")
loguru_config.format	str	Log format: text or json
shutdown_config.timeout_seconds	float	Graceful shutdown timeout in seconds (default: 30.0)
shutdown_config.enabled	bool	Whether shutdown timeout is enabled (default: true)

Dependencies

Key runtime dependencies:

• FastAPI >= 0.136.1
• Pydantic >= 2.11.7
• Uvicorn >= 0.30.5
• Loguru >= 0.7.2
• PyYAML >= 6.0.2
• cachetools >= 5.5.0

For a complete list, see pyproject.toml.

Development

git clone https://github.com/NFUChen/PySpring.git
cd PySpring
pip install -e ".[dev]"
pytest

License

This project is licensed under the MIT License - see the LICENSE file for details.