FastAPI

1

tell me 20 features of FastAPI with code example

Here are 20 features of FastAPI along with code examples to demonstrate each feature:

  1. Fast: FastAPI is one of the fastest Python web frameworks available.

    from fastapi import FastAPI

app = FastAPI()

@app.get("/")
async def read_root():
    return {"message": "Hello, FastAPI!"}

  2. Path Parameters: Define dynamic paths with parameters.

    @app.get("/items/{item_id}")
async def read_item(item_id: int):
    return {"item_id": item_id}

  3. Query Parameters: Support for query parameters.

    @app.get("/items/")
async def read_item(skip: int = 0, limit: int = 10):
    return {"skip": skip, "limit": limit}

  4. Request Body: Accept request bodies with Pydantic models.

    from pydantic import BaseModel

class Item(BaseModel):
    name: str
    description: str = None
    price: float

@app.post("/items/")
async def create_item(item: Item):
    return item

  5. Form Data: Accept form data in requests.

    from fastapi import Form

@app.post("/login/")
async def login(username: str = Form(...), password: str = Form(...)):
    return {"username": username}

  6. File Uploads: Handle file uploads.

    from fastapi import File, UploadFile

@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile = File(...)):
    return {"filename": file.filename}

  7. Path Operations: Different HTTP methods (GET, POST, PUT, DELETE).

    @app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    return {"item_id": item_id, **item.dict()}

  8. Response Model: Define response models.

    class ItemResponse(BaseModel):
    name: str
    price: float

@app.get("/items/{item_id}", response_model=ItemResponse)
async def read_item(item_id: int):
    return {"name": "example", "price": 10.0}

  9. Dependencies: Dependency injection system.

    from fastapi import Depends

def get_token(token: str):
    return token

@app.get("/users/")
async def read_users(token: str = Depends(get_token)):
    return {"token": token}

  10. Security: OAuth2 with password and bearer token.

    from fastapi.security import OAuth2PasswordBearer

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

@app.get("/users/me")
async def read_users_me(token: str = Depends(oauth2_scheme)):
    return {"token": token}

  11. Background Tasks: Run background tasks.

    from fastapi import BackgroundTasks

def write_log(message: str):
    with open("log.txt", "a") as log:
        log.write(message)

@app.post("/send-notification/{email}")
async def send_notification(email: str, background_tasks: BackgroundTasks):
    background_tasks.add_task(write_log, f"Notification sent to {email}")
    return {"message": "Notification sent"}

  12. WebSockets: Support for WebSocket.

    from fastapi import WebSocket

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    await websocket.send_text("Hello, WebSocket!")
    await websocket.close()

  13. Middleware: Add middleware for handling requests and responses.

    from fastapi.middleware.cors import CORSMiddleware

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

  14. Events: Startup and shutdown events.

    @app.on_event("startup")
async def startup_event():
    print("Starting up...")

@app.on_event("shutdown")
async def shutdown_event():
    print("Shutting down...")

  15. Templates: Render HTML templates.

    from fastapi.templating import Jinja2Templates
from fastapi import Request

templates = Jinja2Templates(directory="templates")

@app.get("/items/{id}")
async def read_item(request: Request, id: str):
    return templates.TemplateResponse("item.html", {"request": request, "id": id})

  16. Static Files: Serve static files.

    from fastapi.staticfiles import StaticFiles

app.mount("/static", StaticFiles(directory="static"), name="static")

  17. Custom Responses: Return custom responses.

    from fastapi.responses import JSONResponse

@app.get("/custom_response")
async def custom_response():
    return JSONResponse(content={"message": "Custom Response"})

  18. Database Integration: Easily integrate with databases (example with SQLAlchemy).

    from sqlalchemy import create_engine, Column, Integer, String, Sequence
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"
engine = create_engine(SQLALCHEMY_DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

class User(Base):
    __tablename__ = "users"
    id = Column(Integer, Sequence("user_id_seq"), primary_key=True, index=True)
    name = Column(String, index=True)

Base.metadata.create_all(bind=engine)

@app.get("/users/{user_id}")
async def read_user(user_id: int, db: Session = Depends(get_db)):
    user = db.query(User).filter(User.id == user_id).first()
    return user

  19. Asynchronous Support: First-class support for async and await.

    @app.get("/async")
async def read_async():
    await some_async_function()
    return {"message": "Async function called"}

  20. OpenAPI and JSON Schema: Automatically generated OpenAPI and JSON Schema docs.

    # No code needed; FastAPI automatically generates this at /docs and /redoc

These features and examples demonstrate the versatility and powerful capabilities of FastAPI.

2

tell me another 20

Sure! Here are 20 more features of FastAPI along with code examples:

  1. Custom Request Validation: Define custom validation logic for requests.

  2. Custom Exceptions: Define custom exception handlers.

  3. Custom Status Codes: Return custom status codes.

  4. Custom Headers: Set custom headers in responses.

  5. Rate Limiting: Implement rate limiting (using third-party libraries like slowapi).

  6. OAuth2 with JWT: OAuth2 authentication with JWT tokens.

  7. GraphQL: Integrate with GraphQL using graphene.

  8. Event Handling: Handle application-wide events.

  9. CORS: Configure CORS (Cross-Origin Resource Sharing).

  10. HTTP Basic Auth: Implement basic HTTP authentication.

  11. Internationalization (i18n): Support for multiple languages.

  12. APIRouter: Use routers to organize your application.

  13. SQLAlchemy Integration: Use SQLAlchemy for database interactions.

  14. Alembic Integration: Database migrations with Alembic.

  15. Dependency Overrides: Override dependencies for testing or specific use cases.

  16. Custom Routers: Create custom routers for different modules.

  17. WebSocket Authentication: Handle authentication for WebSocket connections.

  18. Custom URL Converters: Create custom URL converters for routes.

  19. CLI Commands: Create custom CLI commands.

  20. Environment Variables: Use environment variables for configuration.

These additional features and examples further illustrate the comprehensive capabilities of FastAPI, making it a versatile and powerful framework for building APIs.

3

tell me anoter 20

Of course! Here are 20 more features of FastAPI along with code examples:

  1. Middleware for Logging: Implement logging with middleware.

  2. Custom Response Class: Create and use custom response classes.

  3. Cookies: Read and set cookies in responses.

  4. Custom Exception Messages: Customize exception messages globally.

  5. Background Task Cleanup: Use background tasks for cleanup.

  6. Streaming Responses: Stream large responses.

  7. Mount Sub-applications: Mount other ASGI applications.

  8. HTTP Redirects: Return HTTP redirects.

  9. File Responses: Serve files as responses.

  10. GraphQL Subscriptions: Implement GraphQL subscriptions.

  11. Versioning: API versioning with path parameters.

  12. OAuth2 Password Flow: Implement OAuth2 password flow with JWT.

  13. Dependency Injection: Advanced use of dependency injection.

  14. Data Validation with Pydantic: Use Pydantic for advanced data validation.

  15. Custom Validation Error Handler: Handle validation errors globally.

  16. API Key Security: Implement API key security.

  17. GraphQL with Ariadne: Use Ariadne for GraphQL endpoints.

  18. AsyncSQLAlchemy: Use async support with SQLAlchemy.

  19. Testing with TestClient: Write tests using FastAPI's TestClient.

  20. Handle Multiple Applications: Serve multiple FastAPI applications.

  21. Role-based Access Control (RBAC): Implement RBAC.

: str = Depends(oauth2_scheme)): if security_scopes.scopes and "admin" not in security_scopes.scopes: raise HTTPException(status_code=403, detail="Not enough permissions") return {"username": "admin"}

62. Response Compression: Enable Gzip compression for responses. ```python from fastapi.middleware.gzip import GZipMiddleware

63. Locale Detection: Automatically detect and handle user locales. ```python from fastapi_babel import Babel

64. Token-Based Rate Limiting: Implement token-based rate limiting. ```python from slowapi import Limiter from slowapi.util import get_remote_address

65. WebSocket Broadcast: Broadcast messages to multiple WebSocket clients. ```python from fastapi import WebSocket, WebSocketDisconnect from typing import List

66. Dependency Override in Tests: Override dependencies in tests. ```python from fastapi.testclient import TestClient

67. Request Hooks: Implement hooks to process requests before they reach the route. python @app.middleware("http") async def add_process_time_header(request: Request, call_next): start_time = time.time() response = await call_next(request) process_time = time.time() - start_time response.headers["X-Process-Time"] = str(process_time) return response

  1. FastAPI with Celery: Integrate FastAPI with Celery for task queues.

  2. SQLAlchemy with Alembic: Integrate SQLAlchemy with Alembic for migrations.

  3. Admin Interface: Integrate with an admin interface (e.g., fastapi-admin).

These features, along with the previously mentioned ones, illustrate the extensive functionality and flexibility that FastAPI offers for building modern web APIs and applications.

4

give me another 20

Sure! Here are another 20 features of FastAPI along with code examples:

  1. Custom Dependency Classes: Use custom classes as dependencies.

  2. SQLAlchemy with FastAPI: Integrate SQLAlchemy ORM with FastAPI.

  3. Testing Dependencies: Override dependencies in tests.

  4. Peewee ORM: Use Peewee ORM with FastAPI.

  5. CORS Configuration: Configure CORS for specific routes.

  6. Custom Field Validation: Use Pydantic for custom field validation.

  7. Event-driven Architecture: Use event handlers for different stages.

  8. WebSocket Middleware: Implement middleware for WebSocket connections.

  9. Dynamic URL Path: Define dynamic URL paths with custom path converters.

  10. Conditional Response: Return different responses based on conditions.

  11. Dynamic Middleware: Apply middleware dynamically.

  12. Global Exception Handling: Handle exceptions globally.

  13. Custom 404 Page: Customize the 404 error page.

  14. Basic Authentication: Implement HTTP Basic Authentication.

  15. Advanced Dependency Injection: Use multiple levels of dependencies.

  16. Database Connection Pooling: Implement connection pooling.

  17. Custom Dependencies with State: Use FastAPI state to share dependencies.

  18. Dependency Injection with Context Managers: Use context managers as dependencies.

  19. GraphQL with Strawberry: Use Strawberry for GraphQL API.

  20. HTML Forms Handling: Handle HTML forms with FastAPI.

  21. FastAPI with Django ORM: Use FastAPI with Django ORM.

  22. SQLAlchemy with PostgreSQL: Use SQLAlchemy with PostgreSQL.

  23. Data Encryption: Encrypt and decrypt data in FastAPI.

  24. Rate Limiting with Redis: Use Redis for rate limiting.

  25. WebSocket Authentication with JWT: Authenticate WebSocket connections with JWT.

  26. Throttling: Implement request throttling.

  27. HTML Template Rendering: Render HTML templates with Jinja2.

  28. Rate Limiting with FastAPI-Limiter: Use fastapi-limiter for rate limiting.

  29. GraphQL with Graphene: Use Graphene for GraphQL APIs.

  30. Event Notifications: Implement event notifications. ```python from pydantic import BaseModel

These features and examples illustrate the extensive and diverse capabilities of FastAPI for creating robust and scalable APIs and applications.

5

I apologize for the previous issues. Here are the 20 features with properly formatted code examples:

101. Automatic Documentation Generation

FastAPI automatically generates interactive API documentation at /docs (Swagger UI) and /redoc (ReDoc).

102. Dependency Injection for Classes

Use class-based dependencies.

103. GraphQL Subscriptions

Implement GraphQL subscriptions with WebSockets.

104. Redis Cache Integration

Use Redis for caching.

105. Dependency Overriding

Override dependencies for testing.

106. Pydantic Settings Management

Use Pydantic for settings management.

107. Database Transactions

Use transactions with databases.

108. OpenAPI Customization

Customize the OpenAPI schema.

109. Async Task Queues with RQ

Use RQ for background tasks.

110. File Streaming

Stream files to the client.

111. Rate Limiting with IP Address

Implement rate limiting based on IP addresses.

112. Streaming JSON Responses

Stream JSON responses to the client.

113. Session Management

Use sessions for user management.

114. WebSocket Chat

Implement a WebSocket chat server.

115. Advanced Dependency Injection

Use advanced dependency injection with classes and methods.

116. Request Validation

Custom request validation with Pydantic.

117. OAuth2 with JWT

Implement OAuth2 authentication with JWT tokens.

118. Handling Background Tasks

Run background tasks in FastAPI.

119. WebSocket Authentication

Handle authentication for WebSocket connections.

120. SQLAlchemy Integration with FastAPI

Use SQLAlchemy ORM with FastAPI.

121. Role-Based Access Control (RBAC)

Implement RBAC with FastAPI.

122. Custom Middleware

Create and use custom middleware in FastAPI.

123. Request Validation with Dependencies

Validate requests with custom dependencies.

124. Dependency Injection for Multiple Levels

Use dependencies that depend on other dependencies.

125. Rate Limiting with FastAPI-Limiter

Implement rate limiting using the fastapi-limiter library.

These additional features and examples further illustrate the flexibility and power of FastAPI in building modern web APIs and applications.

6

I have 4 routes in FastAPI. Out of 4, 3 of them having tenant_id like below

I want to keep middleware where I would prepend tenant_id without specifically mention in each route.

To apply a middleware that automatically handles the tenant_id in FastAPI, you can create a middleware component that extracts the tenant_id from the path of incoming requests and then makes it conveniently available throughout your application, perhaps by attaching it to the request state.

Here's how you can define such middleware:

  1. Create a Middleware: This middleware will capture requests, extract the tenant_id from the path if present, and then store it in the request state for use in your endpoint functions.

  2. Use Starlette's Request Object: Since FastAPI is built on Starlette, you can utilize the request object's state to pass around the tenant_id.

Here's an example of how you might implement this:

Explanation

  • Middleware: TenantMiddleware checks each request's URL path for a tenant_id pattern. If found, it stores this tenant_id in the request.state, which is accessible throughout the lifecycle of the request.

  • Regex Usage: The regex r'^/(\d+)/' is used to extract the first group of digits in the path, which is assumed to be the tenant_id. You can adjust the regex to match the specific format of your tenant_id.

  • Endpoint: In the endpoint function, tenant_id is retrieved from request.state. If it's not found (i.e., None), an HTTP exception is raised. This centralizes the handling of tenant_id and avoids repeating the extraction logic in each endpoint.

By using this middleware, you simplify your route handlers by removing the need to manually extract the tenant_id from the path, ensuring that the ID handling logic is consistent and easily maintainable across your application.

7

Dependency Injection for Multiple Levels

how to use this in FastAPI in realtime

Dependency Injection (DI) in FastAPI is a powerful feature that allows you to decouple components and ensure that dependencies are managed automatically by the framework. This makes your code cleaner, easier to test, and more modular. FastAPI uses a system where dependencies are "injected" into your path operation functions as arguments.

Here’s a step-by-step guide to using dependency injection in FastAPI, especially focusing on multiple levels of dependencies:

1. Basic Dependency

A dependency in FastAPI can be any callable that returns a value. These are often used to provide database connections, configurations, or custom logic that can be reused across multiple endpoints.

2. Multiple Level Dependencies

Dependencies can also depend on other dependencies, creating a chain or a tree of dependencies. This is useful when a particular service or component requires another service.

3. Sub-dependencies

Here’s how you might define a sub-dependency where one dependency function relies on another. This allows you to build a complex but manageable dependency injection system.

4. Using Classes for Dependencies

You can also use classes for organizing dependencies. This is useful when your dependencies have state or configuration.

5. Advanced Usage with Scopes

FastAPI allows you to specify how often a dependency should be reused. This can be configured using use_cache in the Depends function.

Real-Time Considerations

When considering real-time applications or features:

  • Cache Control: Managing the use_cache parameter carefully ensures that dependencies are re-evaluated as needed, which is critical in high-concurrency or rapidly-changing data environments.

  • Async Dependencies: If your dependency involves IO operations (like database or network calls), it should ideally be asynchronous to avoid blocking the server loop.

  • Error Handling: Dependencies can also perform error handling or security checks, which can preemptively return errors before reaching the actual business logic of your endpoints.

This approach to dependency injection keeps your FastAPI application modular, testable, and clean, enabling you to manage complex dependencies efficiently in real-time operations.

8

Give me some real time sample for "Error Handling" in FastAPI

Error handling in FastAPI is critical for managing exceptions and providing meaningful error responses to clients. FastAPI offers several built-in tools to streamline error handling, including exception handlers and dependency injections that can pre-validate data or manage security concerns. Here, I'll show you how to effectively use FastAPI’s features to handle errors in a practical, real-world application context.

1. Using HTTPException for Simple Error Handling

One of the simplest ways to handle errors in FastAPI is by raising an HTTPException when something goes wrong.

2. Custom Exception Handlers

You can define custom exception handlers to catch specific exceptions and return custom responses. This is particularly useful for catching broad exceptions that might be raised by libraries or your own code.

3. Custom Dependency with Error Handling

Dependencies in FastAPI can be used to encapsulate security logic, parameter validation, or any other preparatory steps that should happen before an endpoint function is called.

4. Handling Errors in Background Tasks

Background tasks in FastAPI can also benefit from structured error handling, especially to avoid silent failures.

Real-World Considerations

  • Extensive Use of HTTPException: For API endpoints, using HTTPException is common practice for immediately stopping request processing and responding with a specific HTTP status code.

  • Logging: Ensure that all exceptions are logged properly. This helps in debugging and understanding the paths that lead to errors.

  • User Feedback: Customize error messages to be helpful but avoid exposing sensitive details or implementation specifics that could be exploited.

These examples cover various scenarios of error handling in FastAPI, each tailored to different aspects of an application's needs, from simple validations to managing asynchronous tasks.

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