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Author SHA1 Message Date
Sebastián Ramírez
01fb6bfef8 🔧 Add FastAPI Agents Skill 2026-02-24 00:30:44 +01:00
github-actions[bot]
2f9c914d44 📝 Update release notes
[skip ci]
2026-02-23 18:48:43 +00:00
Sebastián Ramírez
0cf27ecf88 👥 Update FastAPI People - Experts (#14972)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Motov Yurii <109919500+YuriiMotov@users.noreply.github.com>
2026-02-23 19:47:59 +01:00
github-actions[bot]
3f30ca1a5e 📝 Update release notes
[skip ci]
2026-02-23 18:32:32 +00:00
Motov Yurii
6af3832126 👷 Allow skipping benchmark job in test workflow (#14974) 2026-02-23 19:31:54 +01:00
4 changed files with 1116 additions and 463 deletions

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@@ -208,4 +208,4 @@ jobs:
uses: re-actors/alls-green@release/v1
with:
jobs: ${{ toJSON(needs) }}
allowed-skips: coverage-combine,test
allowed-skips: coverage-combine,test,benchmark

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@@ -7,6 +7,11 @@ hide:
## Latest Changes
### Internal
* 👥 Update FastAPI People - Experts. PR [#14972](https://github.com/fastapi/fastapi/pull/14972) by [@tiangolo](https://github.com/tiangolo).
* 👷 Allow skipping `benchmark` job in `test` workflow. PR [#14974](https://github.com/fastapi/fastapi/pull/14974) by [@YuriiMotov](https://github.com/YuriiMotov).
## 0.132.0
### Breaking Changes

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---
name: fastapi
description: FastAPI best practices and conventions. Use when working with FastAPI APIs and Pydantic models for them. Keeps FastAPI code clean and up to date with the latest features and patterns, updated with new versions. Write new code or refactor and update old code.
---
# FastAPI
Official FastAPI skill to write code with best practices, keeping up to date with new versions and features.
## Use the `fastapi` CLI
To run the development server, in localhost, with reload:
```bash
fastapi dev
```
And to run the production server:
```bash
fastapi run
```
### Add an entrypoint in `pyproject.toml`
FastAPI CLI will read the entrypoint in `pyproject.toml` to know where the FastAPI app is declared.
```toml
[tool.fastapi]
entrypoint = "my_app.main:app"
```
This way the same command can be used without having to pass a path every time.
### Use `fastapi` with a path
When adding the entrypoint to `pyproject.toml` is not possible, or the user explicitly asks not to, or it's running an independent small app, you can pass the path to the file to the `fastapi` command:
```bash
fastapi dev my_app/main.py
```
## Use `Annotated`
Always prefer the `Annotated` style for parameter and dependency declarations.
It keeps the function signatures working in other contexts, respects the types, allows reusability.
### In Parameter Declarations
Use `Annotated` for parameter declarations, including `Path`, `Query`, `Header`, etc.:
```python
from typing import Annotated
from fastapi import FastAPI, Path, Query
app = FastAPI()
@app.get("/items/{item_id}")
async def read_item(
item_id: Annotated[int, Path(ge=1, description="The item ID")],
q: Annotated[str | None, Query(max_length=50)] = None,
):
return {"message": "Hello World"}
```
instead of:
```python
# DO NOT DO THIS
from fastapi import FastAPI, Path, Query
app = FastAPI()
@app.get("/items/{item_id}")
async def read_item(
item_id: int = Path(ge=1, description="The item ID"),
q: str | None = Query(default=None, max_length=50),
):
return {"message": "Hello World"}
```
### For Dependencies
Use `Annotated` for dependencies with `Depends()`.
Unless asked not to, create a new type alias for the dependency to allow re-using it.
```python
from typing import Annotated
from fastapi import Depends, FastAPI
app = FastAPI()
def get_current_user():
return {"username": "johndoe"}
CurrentUserDep = Annotated[dict, Depends(get_current_user)]
@app.get("/items/")
async def read_item(current_user: CurrentUserDep):
return {"message": "Hello World"}
```
instead of:
```python
# DO NOT DO THIS
from fastapi import Depends, FastAPI
app = FastAPI()
def get_current_user():
return {"username": "johndoe"}
@app.get("/items/")
async def read_item(current_user: dict = Depends(get_current_user)):
return {"message": "Hello World"}
```
## Do not use Ellipsis for *path operations*
Do not use `...` as a default value for required parameters.
Do this, without Ellipsis (`...`):
```python
from typing import Annotated
from fastapi import FastAPI, Query
app = FastAPI()
@app.get("/items/")
async def read_item(project_id: Annotated[int, Query()]):
return {"message": "Hello World"}
```
instead of this:
```python
# DO NOT DO THIS
from fastapi import FastAPI, Query
app = FastAPI()
@app.get("/items/")
async def read_item(project_id: int = Query(...)):
return {"message": "Hello World"}
```
## Do not use Ellipsis for Pydantic models
Do this, without Ellipsis (`...`):
```python
from fastapi import FastAPI
from pydantic import BaseModel, Field
app = FastAPI()
class Item(BaseModel):
name: str
description: str | None = None
price: float = Field(gt=0)
@app.post("/items/")
async def create_item(item: Item):
return {"message": "Hello World"}
```
instead of this:
```python
# DO NOT DO THIS
from fastapi import FastAPI
from pydantic import BaseModel, Field
app = FastAPI()
class Item(BaseModel):
name: str = ...
description: str | None = None
price: float = Field(..., gt=0)
@app.post("/items/")
async def create_item(item: Item):
return {"message": "Hello World"}
```
## Return Type or Response Model
When possible, include a return type. It will be used to validate, filter, document, and serialize the response.
```python
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
name: str
description: str | None = None
@app.get("/items/me")
async def get_item() -> Item:
return Item(name="Plumbus", description="All-purpose home device")
```
**Important**: Return types or response models are what filter data ensuring no sensitive information is exposed. And they are used to serialize data with Pydantic, this is the main idea that can increase response performance.
The return type doesn't have to be a Pydantic model, it could be a different type, like a list of Pydantic models, or a dict, etc.
### When to use `response_model` instead
If the return type is not the same as the type that you want to use to validate, filter, serialize, use the `response_model` parameter on the decorator instead.
```python
from typing import Any
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
name: str
description: str | None = None
@app.get("/items/me", response_model=Item)
async def get_item() -> Any:
return {"name": "Foo", "description": "A very nice Item"}
```
This can be in particular useful when filtering data to expose only the public fields, and avoid exposing sensitive information.
```python
from typing import Any
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class InternalItem(BaseModel):
name: str
description: str | None = None
secret_key: str
class Item(BaseModel):
name: str
description: str | None = None
@app.get("/items/me", response_model=Item)
async def get_item() -> Any:
item = InternalItem(
name="Foo", description="A very nice Item", secret_key="supersecret"
)
return item
```
## Performance
Do not use `ORJSONResponse` or `UJSONResponse`, they are deprecated.
Instead declare a return type or response model. Pydantic will handle the data serialization in the Rust side.
### Including Routers
When declaring routers, prefer to add router level parameters like prefix, tags, etc. to the router itself, instead of in `include_router()`.
Do this:
```python
from fastapi import APIRouter, FastAPI
app = FastAPI()
router = APIRouter(prefix="/items", tags=["items"])
@router.get("/")
async def list_items():
return []
# In main.py
app.include_router(router)
```
instead of this:
```python
# DO NOT DO THIS
from fastapi import APIRouter, FastAPI
app = FastAPI()
router = APIRouter()
@router.get("/")
async def list_items():
return []
# In main.py
app.include_router(router, prefix="/items", tags=["items"])
```
There could be exceptions but try to follow this convention.
Apply shared dependencies at the router level via `dependencies=[Depends(...)]`.
## Dependency Injection
Use dependencies when:
* They can't be declared in Pydantic validation and require additional logic
* The logic depends on external resources or could block in any other way
* Other dependencies need their results (it's a sub-dependency)
* The logic can be shared by multiple endpoints to do things like error early, authentication, etc.
* They need to handle cleanup (e.g., DB sessions, file handles), using dependencies with `yield`
* Their logic needs request input data, like headers, query parameters, etc.
### Dependencies with `yield` and `scope`
When the using dependencies with `yield`, they can have a `scope` that defines when the exit code is run.
Use the default scope `"request"` to run the exit code after the response is sent back.
```python
from typing import Annotated
from fastapi import Depends, FastAPI
app = FastAPI()
def get_db():
db = DBSession()
try:
yield db
finally:
db.close()
DBDep = Annotated[DBSession, Depends(get_db)]
@app.get("/items/")
async def read_items(db: DBDep):
return db.query(Item).all()
```
Use the scope `"function"` when they should run the exit code after the response data is generated but before the response is sent back to the client.
```python
from typing import Annotated
from fastapi import Depends, FastAPI
app = FastAPI()
def get_username():
try:
yield "Rick"
finally:
print("Cleanup up before response is sent")
UserNameDep = Annotated[str, Depends(get_username, scope="function")]
@app.get("/users/me")
def get_user_me(username: UserNameDep):
return username
```
### Class Dependencies
Avoid creating class dependencies when possible.
If a class is needed, instead create a regular function dependency that return a class instance.
Do this:
```python
from dataclasses import dataclass
from typing import Annotated
from fastapi import Depends, FastAPI
app = FastAPI()
@dataclass
class CommonQueryParams:
q: str | None = None
skip: int = 0
limit: int = 100
def get_common_params(
q: str | None = None, skip: int = 0, limit: int = 100
) -> CommonQueryParams:
return CommonQueryParams(q=q, skip=skip, limit=limit)
CommonsDep = Annotated[CommonQueryParams, Depends(get_common_params)]
@app.get("/items/")
async def read_items(commons: CommonsDep):
return {"q": commons.q, "skip": commons.skip, "limit": commons.limit}
```
instead of this:
```python
# DO NOT DO THIS
from typing import Annotated
from fastapi import Depends, FastAPI
app = FastAPI()
class CommonQueryParams:
def __init__(self, q: str | None = None, skip: int = 0, limit: int = 100):
self.q = q
self.skip = skip
self.limit = limit
@app.get("/items/")
async def read_items(commons: Annotated[CommonQueryParams, Depends()]):
return {"q": commons.q, "skip": commons.skip, "limit": commons.limit}
```
## Async vs Sync *path operations*
Use `async` *path operations* only when fully certain that the logic called inside is compatible with async and await (it's called with `await`) or doesn't block.
```python
from fastapi import FastAPI
app = FastAPI()
# Use async def when calling async code
@app.get("/async-items/")
async def read_async_items():
data = await some_async_library.fetch_items()
return data
# Use plain def when calling blocking/sync code or when in doubt
@app.get("/items/")
def read_items():
data = some_blocking_library.fetch_items()
return data
```
In case of doubt, or by default, use regular `def` functions, those will be run in a threadpool so they don't block the event loop.
The same rules apply to dependencies.
Make sure blocking code is not run inside of `async` functions. The logic will work, but will damage heavily the performance.
### Asyncer
When needing to run blocking code inside of async functions, or async code inside of blocking functions, suggest using Asyncer.
Install:
```bash
uv add asyncer
```
Run blocking sync code inside of async with `asyncify()`:
```python
from asyncer import asyncify
from fastapi import FastAPI
app = FastAPI()
def do_blocking_work(name: str) -> str:
# Some blocking I/O operation
return f"Hello {name}"
@app.get("/items/")
async def read_items():
result = await asyncify(do_blocking_work)(name="World")
return {"message": result}
```
And run async code inside of blocking sync code with `syncify()`:
```python
from asyncer import syncify
from fastapi import FastAPI
app = FastAPI()
async def do_async_work(name: str) -> str:
return f"Hello {name}"
@app.get("/items/")
def read_items():
result = syncify(do_async_work)(name="World")
return {"message": result}
```
## Use uv
If uv is available, use it to manage dependencies.
## SQLModel for SQL databases
When working with SQL databases, prefer using SQLModel as it is integrated with Pydantic and will allow declaring data validation with the same models.
## Do not use Pydantic RootModels
Do not use Pydantic `RootModel`, instead use regular type annotations with `Annotated` and Pydantic validation utilities.
For example for a list with validations you could do:
```python
from typing import Annotated
from fastapi import Body, FastAPI
from pydantic import Field
app = FastAPI()
@app.post("/items/")
async def create_items(items: Annotated[list[int], Field(min_length=1), Body()]):
return items
```
instead of:
```python
# DO NOT DO THIS
from typing import Annotated
from fastapi import FastAPI
from pydantic import Field, RootModel
app = FastAPI()
class ItemList(RootModel[Annotated[list[int], Field(min_length=1)]]):
pass
@app.post("/items/")
async def create_items(items: ItemList):
return items
```
FastAPI supports these type annotations and will create a Pydantic `TypeAdapter` for them, so that types can work as normally.
## Use one HTTP operation per function
Don't mix HTTP operations in a single function, having one function per HTTP operation helps separate concerns and organize the code.
Do this:
```python
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
name: str
@app.get("/items/")
async def list_items():
return []
@app.post("/items/")
async def create_item(item: Item):
return item
```
instead of this:
```python
# DO NOT DO THIS
from fastapi import FastAPI, Request
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
name: str
@app.api_route("/items/", methods=["GET", "POST"])
async def handle_items(request: Request):
if request.method == "GET":
return []
# ...
```