/**
 * This class provides a skeletal implementation of the {@code Iterator} interface for sequences
 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * {@snippet :
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {
 *       protected Integer computeNext(Integer previous) {

import com.google.common.annotations.GwtCompatible;

/**
 * A time source; returns a time value representing the number of nanoseconds elapsed since some
 * fixed but arbitrary point in time. Note that most users should use {@link Stopwatch} instead of
 * interacting with this class directly.
 *
 * <p><b>Warning:</b> this interface can only be used to measure elapsed time, not wall time.
 *
 * @author Kevin Bourrillion

Наприклад, вона не приймає об'єкти типу `datetime`, оскільки вони не сумісні з JSON.

Отже, об'єкт типу `datetime` потрібно перетворити в рядок `str`, який містить дані в <a href="https://en.wikipedia.org/wiki/ISO_8601" class="external-link" target="_blank">ISO форматі</a>.

Тим самим способом ця база даних не прийматиме об'єкт типу Pydantic model (об'єкт з атрибутами), а лише `dict`.

Ви можете використовувати `jsonable_encoder` для цього.

## 結論

透過這個教學，你應該對**環境變數**是什麼以及如何在 Python 中使用它們有了基本的了解。

你也可以在<a href="https://zh.wikipedia.org/wiki/%E7%8E%AF%E5%A2%83%E5%8F%98%E9%87%8F" class="external-link" target="_blank">環境變數 - 維基百科</a> (<a href="https://en.wikipedia.org/wiki/Environment_variable" class="external-link" target="_blank">Wikipedia for Environment Variable</a>) 中了解更多關於它們的資訊。

在許多情況下，環境變數的用途和適用性可能不會立刻顯現。但是在開發過程中，它們會在許多不同的場景中出現，因此瞭解它們是非常必要的。

Copy the example in a file `main.py`:

{* ../../docs_src/security/tutorial001_an_py39.py *}

## Run it { #run-it }

/// info

The <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a> package is automatically installed with **FastAPI** when you run the `pip install "fastapi[standard]"` command.

  public RemovalCause getCause() {
    return cause;
  }

  /**
   * Returns {@code true} if there was an automatic removal due to eviction (the cause is neither
   * {@link RemovalCause#EXPLICIT} nor {@link RemovalCause#REPLACED}).
   */
  public boolean wasEvicted() {
    return cause.wasEvicted();
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

import static org.mockito.Mockito.verify;

import java.util.Arrays;
import java.util.Optional;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

/**
 * Tests for {@link DosError}.  Since {@link DosError} only contains
 * constants, the tests exercise the data and small helper logic in this
 * test class.
 */
public class DosErrorTest {
    private static Optional<Integer> findNtStatus(int dosErrorCode) {

## Detalles sobre el objeto `Request`

Como **FastAPI** es en realidad **Starlette** por debajo, con una capa de varias herramientas encima, puedes usar el objeto <a href="https://www.starlette.io/requests/" class="external-link" target="_blank">`Request`</a> de Starlette directamente cuando lo necesites.

Sie können Cookies auch erstellen, wenn Sie eine `Response` direkt in Ihrem Code zurückgeben.

Dazu können Sie eine Response erstellen, wie unter [Eine Response direkt zurückgeben](response-directly.md){.internal-link target=_blank} beschrieben.

Setzen Sie dann Cookies darin und geben Sie sie dann zurück:

{* ../../docs_src/response_cookies/tutorial001.py hl[10:12] *}

/// tip | Tipp

Você também pode criar cookies ao retornar uma `Response` diretamente no seu código.

Para fazer isso, você pode criar uma resposta como descrito em [Retornando uma Resposta Diretamente](response-directly.md){.internal-link target=_blank}.

Então, defina os cookies nela e a retorne:

{* ../../docs_src/response_cookies/tutorial001.py hl[10:12] *}

/// tip | Dica