{!../../../docs_src/python_types/tutorial009.py!}
```

`str` yerine `Optional[str]` kullanmak editorün bu değerin her zaman `str` tipinde değil bazen `None` tipinde de olabileceğini belirtir ve hataları tespit etmemizde yardımcı olur.

#### Generic tipler

Köşeli parantez içinde tip parametreleri alan bu türler, örneğin:

* `List`
* `Tuple`
* `Set`
* `Dict`
* `Optional`
* ...and others.

Burada "yol" bağlantıda bulunan ilk `/` ile başlayan ve sonrasında gelen kısmı ifade eder.

Yani, şu şekilde bir bağlantıda:

```
https://example.com/items/foo
```

... yol şöyle olur:

```
/items/foo
```

!!! info "Bilgi"
    "Yol" genellikle "<abbr title="Endpoint: Bitim Noktası">endpoint</abbr>" veya "<abbr title="Route: Yönlendirme/Yön">route</abbr>" olarak adlandırılır.

Remember that dependencies can have sub-dependencies?

`get_current_user` will have a dependency with the same `oauth2_scheme` we created before.

The same as we were doing before in the *path operation* directly, our new dependency `get_current_user` will receive a `token` as a `str` from the sub-dependency `oauth2_scheme`:

=== "Python 3.10+"

    ```Python hl_lines="25"
    {!> ../../../docs_src/security/tutorial002_an_py310.py!}

    E.g. `pip install email-validator`
    or `pip install pydantic[email]`.

And we are using this model to declare our input and the same model to declare our output:

=== "Python 3.10+"

    ```Python hl_lines="16"
    {!> ../../../docs_src/response_model/tutorial002_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="18"

```Python hl_lines="16"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

## Dependency override

Now we create the dependency override and add it to the overrides for our app.

```Python hl_lines="19-24  27"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

!!! tip

    You put it on top of a function. Like a pretty decorative hat (I guess that's where the term came from).

    A "decorator" takes the function below and does something with it.

    In our case, this decorator tells **FastAPI** that the function below corresponds to the **path** `/` with an **operation** `get`.

    It is the "**path operation decorator**".

You can also use the other operations:

---

"_**Netflix** is pleased to announce the open-source release of our **crisis management** orchestration framework: **Dispatch**! [built with **FastAPI**]_"

---

"_**Netflix** is pleased to announce the open-source release of our **crisis management** orchestration framework: **Dispatch**! [built with **FastAPI**]_"

So, the frontend (that runs in the browser) would try to reach `/openapi.json` and wouldn't be able to get the OpenAPI schema.

Because we have a proxy with a path prefix of `/api/v1` for our app, the frontend needs to fetch the OpenAPI schema at `/api/v1/openapi.json`.

```mermaid
graph LR

browser("Browser")
proxy["Proxy on http://0.0.0.0:9999/api/v1/app"]
server["Server on http://127.0.0.1:8000/app"]

{!../../../docs_src/nosql_databases/tutorial001.py!}
```

We will use this model in our *path operation function*, so, we don't include in it the `hashed_password`.

### `UserInDB` model

Now, let's create a `UserInDB` model.

This will have the data that is actually stored in the database.

We don't create it as a subclass of Pydantic's `BaseModel` but as a subclass of our own `User`, because it will have all the attributes in `User` plus a couple more: