```
    pip install "uvicorn[standard]"
    ```

    And the same for each of the optional dependencies that you want to use.

## Advanced User Guide

There is also an **Advanced User Guide** that you can read later after this **Tutorial - User guide**.

The **Advanced User Guide**, builds on this, uses the same concepts, and teaches you some extra features.

<div class="termy">

```console
$ pip install jinja2

---> 100%
```

</div>

## Using `Jinja2Templates`

* Import `Jinja2Templates`.
* Create a `templates` object that you can re-use later.
* Declare a `Request` parameter in the *path operation* that will return a template.

    ```Python hl_lines="9"
    {!> ../../../docs_src/path_params_numeric_validations/tutorial003_an.py!}
    ```

## Number validations: greater than or equal

With `Query` and `Path` (and others you'll see later) you can declare number constraints.

Here, with `ge=1`, `item_id` will need to be an integer number "`g`reater than or `e`qual" to `1`.

=== "Python 3.9+"

    ```Python hl_lines="10"

We will use `Session` (the one imported from SQLAlchemy) later.

To create the `SessionLocal` class, use the function `sessionmaker`:

```Python hl_lines="11"
{!../../../docs_src/sql_databases/sql_app/database.py!}
```

### Create a `Base` class

Now we will use the function `declarative_base()` that returns a class.

## OpenAPI y documentación de API

Si quieres devolver códigos de estado y respuestas adicionales directamente, estas no estarán incluidas en el schema de OpenAPI (documentación de API), porque FastAPI no tiene una manera de conocer de antemano lo que vas a devolver.

Todos los bloques de código se pueden copiar y usar directamente (en realidad son archivos Python probados).

Para ejecutar cualquiera de los ejemplos, copia el código en un archivo llamado `main.py`, y ejecuta `uvicorn` de la siguiente manera en tu terminal:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

* **Sin comprometerse** con bases de datos, frontend, etc. Pero permitiendo integración fácil con todos ellos.

### "Plug-ins" ilimitados

O dicho de otra manera, no hay necesidad para "plug-ins". Importa y usa el código que necesites.

But you can still document it as described in [Additional Responses in OpenAPI](additional-responses.md){.internal-link target=_blank}.

The `security_scopes` object (of class `SecurityScopes`) also provides a `scope_str` attribute with a single string, containing those scopes separated by spaces (we are going to use it).

We create an `HTTPException` that we can re-use (`raise`) later at several points.

## Main **FastAPI** app

And now in the file `sql_app/main.py` let's integrate and use all the other parts we created before.

### Create the database tables