What is the problem, question, or error?

        Write a short description telling me what you are doing, what you expect to happen, and what is currently happening.
      placeholder: |
        * Open the browser and call the endpoint `/`.
        * It returns a JSON with `{"Hello": "World"}`.
        * But I expected it to return `{"Hello": "Sara"}`.
    validations:
      required: true
  - type: dropdown
    id: os

So, let's review it from that simplified point of view:

* The user types the `username` and `password` in the frontend, and hits `Enter`.
* The frontend (running in the user's browser) sends that `username` and `password` to a specific URL in our API (declared with `tokenUrl="token"`).
* The API checks that `username` and `password`, and responds with a "token" (we haven't implemented any of this yet).

# Requestbody

Wenn Sie Daten von einem <abbr title="Client: Eine Software, die sich mit einem Server verbindet.">Client</abbr> (sagen wir, einem Browser) zu Ihrer API senden, dann senden Sie diese als einen **Requestbody** (Deutsch: Anfragekörper).

Ein **Request**body sind Daten, die vom Client zu Ihrer API gesendet werden. Ein **Response**body (Deutsch: Antwortkörper) sind Daten, die Ihre API zum Client sendet.

```Python hl_lines="6-7"
{!../../../docs_src/query_params/tutorial005.py!}
```

Hier ist `needy` ein erforderlicher Query-Parameter vom Typ `str`.

Wenn Sie in Ihrem Browser eine URL wie:

```
http://127.0.0.1:8000/items/foo-item
```

... öffnen, ohne den benötigten Parameter `needy`, dann erhalten Sie einen Fehler wie den folgenden:

```JSON
{
  "detail": [

```Python hl_lines="6-7"
{!../../../docs_src/query_params/tutorial005.py!}
```

Here the query parameter `needy` is a required query parameter of type `str`.

If you open in your browser a URL like:

```
http://127.0.0.1:8000/items/foo-item
```

...without adding the required parameter `needy`, you will see an error like:

```JSON
{
  "detail": [
    {

     */
    init() {
        /**
         * Calculates width and height of Termynal container.
         * If container is empty and lines are dynamically loaded, defaults to browser `auto` or CSS.
         */
        const containerStyle = getComputedStyle(this.container);
        this.container.style.width = containerStyle.width !== '0px' ?
            containerStyle.width : undefined;

# Request Body

When you need to send data from a client (let's say, a browser) to your API, you send it as a **request body**.

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.

# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

* <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank"><strong>Swagger UI</strong></a>, with interactive exploration, call and test your API directly from the browser.

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

Das Resultat dieses Aufrufs ist etwas, das mit Pythons Standard-<a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a> kodiert werden kann.

Es wird also kein großer `str` zurückgegeben, der die Daten im JSON-Format (als String) enthält. Es wird eine Python-Standarddatenstruktur (z. B. ein `dict`) zurückgegeben, mit Werten und Unterwerten, die alle mit JSON kompatibel sind.

!!! note "Hinweis"