Because of this, **FastAPI** itself provides an alternative API documentation (using ReDoc), which you can access at <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>:

<img src="/img/tutorial/path-params/image02.png">

And then, you could give that JWT token to a user (or bot), and they could use it to perform those actions (drive the car, or edit the blog post) without even needing to have an account, just with the JWT token your API generated for that.

Using these ideas, JWT can be used for way more sophisticated scenarios.

In those cases, several of those entities could have the same ID, let's say `foo` (a user `foo`, a car `foo`, and a blog post `foo`).

## **FastAPI**'s `OAuth2PasswordBearer`

**FastAPI** provides several tools, at different levels of abstraction, to implement these security features.

In this example we are going to use **OAuth2**, with the **Password** flow, using a **Bearer** token. We do that using the `OAuth2PasswordBearer` class.

!!! info

* **`300`** and above are for "Redirection".  Responses with these status codes may or may not have a body, except for `304`, "Not Modified", which must not have one.
* **`400`** and above are for "Client error" responses. These are the second type you would probably use the most.
    * An example is `404`, for a "Not Found" response.

That way, the sub-application will know to use that path prefix for the docs UI.

And the sub-application could also have its own mounted sub-applications and everything would work correctly, because FastAPI handles all these `root_path`s automatically.

You can adapt it to any other NoSQL database like:

* **MongoDB**
* **Cassandra**
* **CouchDB**
* **ArangoDB**
* **ElasticSearch**, etc.

!!! tip

* `/items/{item_id}`

...as we intended.

* They will be marked with a list of tags that contain a single string `"items"`.
    * These "tags" are especially useful for the automatic interactive documentation systems (using OpenAPI).
* All of them will include the predefined `responses`.
* All these *path operations* will have the list of `dependencies` evaluated/executed before them.

    {!> ../../../docs_src/dependencies/tutorial006.py!}
    ```

These dependencies will be executed/solved the same way as normal dependencies. But their value (if they return any) won't be passed to your *path operation function*.

!!! tip
    Some editors check for unused function parameters, and show them as errors.

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## Recensioni

"_[...] I'm using **FastAPI** a ton these days. [...] I'm actually planning to use it for all of my team's **ML services at Microsoft**. Some of them are getting integrated into the core **Windows** product and some **Office** products._"