And as most of your logic will now live in its own specific module, the main file will be quite simple.

### Import `FastAPI` { #import-fastapi }

You import and create a `FastAPI` class as normally.

And we can even declare [global dependencies](dependencies/global-dependencies.md) that will be combined with the dependencies for each `APIRouter`:

  private final transient AvlNode<E> header;

  /**
   * An instance created in {@link #readObject} to be returned from {@link #readResolve}. This field
   * is used only by those methods, and it is never set in a "normal" instance.
   *
   * <p>For more background, see {@code ConcurrentHashMultiset.deserializationReplacement}.
   */
  private transient @Nullable TreeMultiset<E> deserializationReplacement;

  private TreeMultiset(

public class SimpleCircuitBreaker {

    private static final Logger log = LoggerFactory.getLogger(SimpleCircuitBreaker.class);

    /**
     * Circuit breaker states
     */
    public enum State {
        CLOSED, // Normal operation
        OPEN, // Failing, requests blocked
        HALF_OPEN // Testing recovery
    }

    private final String name;
    private final AtomicReference<State> state = new AtomicReference<>(State.CLOSED);

{* ../../docs_src/handling_errors/tutorial001_py310.py hl[1] *}

### Kodunuzda Bir `HTTPException` Raise Etme { #raise-an-httpexception-in-your-code }

`HTTPException`, API’lerle ilgili ek veriler içeren normal bir Python exception’ıdır.

Python exception’ı olduğu için `return` etmezsiniz, `raise` edersiniz.

	// path cannot be so long that you cannot append an 8.3 file
	// name (that is, the directory name cannot exceed MAX_PATH
	// minus 12)." Since MAX_PATH is 260, 260 - 12 = 248.
	//
	// The MSDN docs appear to say that a normal path that is 248 bytes long
	// will work; empirically the path must be less then 248 bytes long.
	if len(path) < 248 {
		// Don't fix. (This is how Go 1.7 and earlier worked,
		// not automatically generating the \\?\ form)

Elle sera appelée par **FastAPI** chaque fois qu’il recevra une requête vers l’URL « / » en utilisant une opération `GET`.

Dans ce cas, c’est une fonction `async`.

---

Vous pouvez aussi la définir comme une fonction normale au lieu de `async def` :

{* ../../docs_src/first_steps/tutorial003_py310.py hl[7] *}

/// note | Remarque

Si vous ne connaissez pas la différence, consultez [Asynchrone : « Pressé ? »](../async.md#in-a-hurry).

@app.post("/items/")
async def create_items(items: ItemList):
    return items

```

FastAPI supports these type annotations and will create a Pydantic `TypeAdapter` for them, so that types can work as normally and there's no need for the custom logic and types in RootModels.

## Use one HTTP operation per function

tangible personal property which is normally used for personal, family,
or household purposes, or (2) anything designed or sold for incorporation
into a dwelling.  In determining whether a product is a consumer product,
doubtful cases shall be resolved in favor of coverage.  For a particular
product received by a particular user, "normally used" refers to a

    * Zuerst werden die Router-Abhängigkeiten ausgeführt, dann die [`dependencies` im Dekorator](dependencies/dependencies-in-path-operation-decorators.md) und dann die normalen Parameterabhängigkeiten.
    * Sie können auch [`Security`-Abhängigkeiten mit `scopes`](../advanced/security/oauth2-scopes.md) hinzufügen.

/// tip | Tipp

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          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution