## Caveat

If you need to perform heavy background computation and you don't necessarily need it to be run by the same process (for example, you don't need to share memory, variables, etc), you might benefit from using other bigger tools like <a href="https://docs.celeryq.dev" class="external-link" target="_blank">Celery</a>.

* ♻️ Refactor tests for new Pydantic 2.2.1. PR [#10115](https://github.com/tiangolo/fastapi/pull/10115) by [@tiangolo](https://github.com/tiangolo).

### Docs

* 📝 Add new docs section, How To - Recipes, move docs that don't have to be read by everyone to How To. PR [#10114](https://github.com/tiangolo/fastapi/pull/10114) by [@tiangolo](https://github.com/tiangolo).

        in response.text
    )


def test_get_http_error():
    response = client.get("/items/3")
    assert response.status_code == 418, response.text
    assert response.content == b"Nope! I don't like 3."


def test_get():
    response = client.get("/items/2")
    assert response.status_code == 200, response.text
    assert response.json() == {"item_id": 2}


def test_openapi_schema():

# Path Operation Advanced Configuration

## OpenAPI operationId

!!! warning
    If you are not an "expert" in OpenAPI, you probably don't need this.

You can set the OpenAPI `operationId` to be used in your *path operation* with the parameter `operation_id`.

You would have to make sure that it is unique for each operation.

```Python hl_lines="6"
{!../../../docs_src/path_operation_advanced_configuration/tutorial001.py!}
```

## Dependencies with `yield` and `except`

If you catch an exception using `except` in a dependency with `yield` and you don't raise it again (or raise a new exception), FastAPI won't be able to notice there was an exception, the same way that would happen with regular Python:

=== "Python 3.9+"

    ```Python hl_lines="15-16"

A **request** body is data sent by the client to your API. A **response** body is the data your API sends to the client.

Your API almost always has to send a **response** body. But clients don't necessarily need to send **request** bodies all the time.

To declare a **request** body, you use <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> models with all their power and benefits.

### Just Modern Python

It's all based on standard **Python type** declarations (thanks to Pydantic). No new syntax to learn. Just standard modern Python.

If you need a 2 minute refresher of how to use Python types (even if you don't use FastAPI), check the short tutorial: [Python Types](python-types.md){.internal-link target=_blank}.

You write standard Python with types:

```Python
from datetime import date

from pydantic import BaseModel

But first, let's check some small concepts.

## In a hurry?

If you don't care about any of these terms and you just need to add security with authentication based on username and password *right now*, skip to the next chapters.

## OAuth2

    return {"Hello": "World"}


@app.get("/items/{item_id}")
async def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

**Note**:

If you don't know, check the _"In a hurry?"_ section about <a href="https://fastapi.tiangolo.com/async/#in-a-hurry" target="_blank">`async` and `await` in the docs</a>.

</details>

### Run it

Run the server with:

Let's talk again about some of the same [Deployment Concepts](concepts.md){.internal-link target=_blank} in terms of containers.

Containers are mainly a tool to simplify the process of **building and deploying** an application, but they don't enforce a particular approach to handle these **deployment concepts**, and there are several possible strategies.

The **good news** is that with each different strategy there's a way to cover all of the deployment concepts. 🎉