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of 46Explain the difference between FastAPI and Flask.
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Key differences:
| FastAPI | Flask |
|---|---|
| ASGI-based (async) | WSGI-based (sync by default) |
| Built-in type validation | Manual validation required |
| Automatic API documentation | Requires extensions |
| Modern Python features | More traditional approach |
| Better performance | Simpler for basic apps |
| Pydantic integration | No built-in serialization |
FastAPI is better for modern APIs requiring high performance and automatic documentation, while Flask offers more flexibility and simplicity for traditional web applications.
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How do you handle different HTTP methods in FastAPI?
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FastAPI provides decorators for all HTTP methods:
from fastapi import FastAPI
app = FastAPI()
@app.get("/items")
def get_items():
return {"method": "GET"}
@app.post("/items")
def create_item():
return {"method": "POST"}
@app.put("/items/{item_id}")
def update_item(item_id: int):
return {"method": "PUT", "item_id": item_id}
@app.delete("/items/{item_id}")
def delete_item(item_id: int):
return {"method": "DELETE", "item_id": item_id}
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How do you handle request bodies in FastAPI?
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Request bodies are handled using Pydantic models:
from pydantic import BaseModel
from fastapi import FastAPI
app = FastAPI()
class Item(BaseModel):
name: str
price: float
is_offer: bool = False
@app.post("/items/")
def create_item(item: Item):
return {"item_name": item.name, "item_price": item.price}
FastAPI automatically validates the request body against the Pydantic model and provides detailed error messages for invalid data.
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How do you customize HTTP status codes in responses?
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You can set status codes using the status_code parameter or Response object:
from fastapi import FastAPI, status, Response
app = FastAPI()
@app.post("/items/", status_code=status.HTTP_201_CREATED)
def create_item():
return {"message": "Item created"}
@app.get("/items/{item_id}")
def get_item(item_id: int, response: Response):
if item_id == 404:
response.status_code = status.HTTP_404_NOT_FOUND
return {"error": "Item not found"}
return {"item_id": item_id}
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What is Pydantic and how does it integrate with FastAPI?
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Pydantic is a data validation library that uses Python type hints to validate data. In FastAPI:
- Request Validation: Automatically validates incoming request data
- Response Serialization: Converts Python objects to JSON
- Documentation: Generates JSON Schema for API docs
- Error Handling: Provides detailed validation error messages
from pydantic import BaseModel, validator
from typing import Optional
class User(BaseModel):
name: str
email: str
age: Optional[int] = None
@validator('email')
def validate_email(cls, v):
if '@' not in v:
raise ValueError('Invalid email')
return v
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How do you define path parameters with validation in FastAPI?
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Path parameters are defined in the function signature with type hints:
from fastapi import FastAPI, Path
app = FastAPI()
@app.get("/items/{item_id}")
def get_item(
item_id: int = Path(..., gt=0, description="The ID of the item")
):
return {"item_id": item_id}
@app.get("/users/{user_id}/items/{item_id}")
def get_user_item(user_id: int, item_id: int):
return {"user_id": user_id, "item_id": item_id}
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How do you handle optional query parameters?
What is the difference between sync and async path operations?
How does FastAPI achieve high performance?
What is ASGI and how does it benefit FastAPI?
How do you handle file uploads in FastAPI?
How do you handle nested Pydantic models?
How do you implement custom validators in Pydantic models?
What is the difference between Pydantic's BaseModel and dataclasses?
How do you implement query parameter validation?
What is dependency injection in FastAPI and why is it useful?
How do you create and use dependencies in FastAPI?
What are sub-dependencies and how do you use them?
How do you implement API key authentication?
How do you handle CORS in FastAPI?
How do you integrate SQLAlchemy with FastAPI?
How do you implement database migrations with FastAPI?
What is middleware in FastAPI and how do you create custom middleware?
How do you handle errors globally using middleware?
How do you implement request/response logging middleware?
How do you test FastAPI applications?
How do you test endpoints with dependencies?
How do you implement background tasks in FastAPI?
How do you implement custom response models?
How do you deploy FastAPI applications?
How do you handle environment configuration in FastAPI?
How do you implement health checks in FastAPI?
How do you implement API versioning in FastAPI?
How do you handle request and response models separately?
How do you handle dependency caching in FastAPI?
How do you implement JWT authentication in FastAPI?
How do you implement role-based access control?
How do you handle database transactions in FastAPI?
How do you test authentication in FastAPI?
How do you implement WebSockets in FastAPI?
How do you handle file streaming in FastAPI?
How do you optimize FastAPI performance?
How do you implement rate limiting in FastAPI?
How do you handle database connection pooling?
How do you implement caching in FastAPI?
How do you monitor FastAPI applications in production?
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