Dependencies - Depends()
and Security()
¶
Depends()
¶
Dependencies are handled mainly with the special function Depends()
that takes a callable.
Here is the reference for it and its parameters.
You can import it directly from fastapi
:
from fastapi import Depends
fastapi.Depends
¶
Depends(dependency=None, *, use_cache=True)
Declare a FastAPI dependency.
It takes a single "dependable" callable (like a function).
Don't call it directly, FastAPI will call it for you.
Read more about it in the FastAPI docs for Dependencies.
Example
from typing import Annotated
from fastapi import Depends, FastAPI
app = FastAPI()
async def common_parameters(q: str | None = None, skip: int = 0, limit: int = 100):
return {"q": q, "skip": skip, "limit": limit}
@app.get("/items/")
async def read_items(commons: Annotated[dict, Depends(common_parameters)]):
return commons
PARAMETER | DESCRIPTION |
---|---|
dependency
|
A "dependable" callable (like a function). Don't call it directly, FastAPI will call it for you, just pass the object directly.
TYPE:
|
use_cache
|
By default, after a dependency is called the first time in a request, if the dependency is declared again for the rest of the request (for example if the dependency is needed by several dependencies), the value will be re-used for the rest of the request. Set
TYPE:
|
Source code in fastapi/param_functions.py
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|
Security()
¶
For many scenarios, you can handle security (authorization, authentication, etc.) with dependencies, using Depends()
.
But when you want to also declare OAuth2 scopes, you can use Security()
instead of Depends()
.
You can import Security()
directly from fastapi
:
from fastapi import Security
fastapi.Security
¶
Security(dependency=None, *, scopes=None, use_cache=True)
Declare a FastAPI Security dependency.
The only difference with a regular dependency is that it can declare OAuth2
scopes that will be integrated with OpenAPI and the automatic UI docs (by default
at /docs
).
It takes a single "dependable" callable (like a function).
Don't call it directly, FastAPI will call it for you.
Read more about it in the FastAPI docs for Security and in the FastAPI docs for OAuth2 scopes.
Example
from typing import Annotated
from fastapi import Security, FastAPI
from .db import User
from .security import get_current_active_user
app = FastAPI()
@app.get("/users/me/items/")
async def read_own_items(
current_user: Annotated[User, Security(get_current_active_user, scopes=["items"])]
):
return [{"item_id": "Foo", "owner": current_user.username}]
PARAMETER | DESCRIPTION |
---|---|
dependency
|
A "dependable" callable (like a function). Don't call it directly, FastAPI will call it for you, just pass the object directly.
TYPE:
|
scopes
|
OAuth2 scopes required for the path operation that uses this Security dependency. The term "scope" comes from the OAuth2 specification, it seems to be intentionaly vague and interpretable. It normally refers to permissions, in cases to roles. These scopes are integrated with OpenAPI (and the API docs at
TYPE:
|
use_cache
|
By default, after a dependency is called the first time in a request, if the dependency is declared again for the rest of the request (for example if the dependency is needed by several dependencies), the value will be re-used for the rest of the request. Set
TYPE:
|
Source code in fastapi/param_functions.py
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