What are FastAPI dependencies and how do I use them?

What are FastAPI dependencies and how do I use them?

FastAPI dependencies are a way to define reusable components that can be injected into your path operations. They help manage things like authentication, database connections, and more.

Can you give me an example of how to create a dependency?

Sure! You can create a dependency by defining a function that takes parameters and returns a value. For example:

from fastapi import Depends

def get_query(q: str = None):
    return q

@app.get("/items/")
async def read_items(query: str = Depends(get_query)):
    return query

How do I handle exceptions in dependencies?

You can handle exceptions in dependencies by using try-except blocks within your dependency function. This allows you to manage errors gracefully.

Are there any built-in dependencies in FastAPI?

Yes, FastAPI provides several built-in dependencies, such as Depends for dependency injection, and HTTPException for error handling.