By only using `BackgroundTasks` (and not `BackgroundTask`), it's then possible to use it as a *path operation function* parameter and have **FastAPI** handle the rest for you, just like when using the `Request` object directly.

It's still possible to use `BackgroundTask` alone in FastAPI, but you have to create the object in your code and return a Starlette `Response` including it.

But you cannot convert from the gibberish back to the password.

##### Why use password hashing { #why-use-password-hashing }

If your database is stolen, the thief won't have your users' plaintext passwords, only the hashes.

So, the thief won't be able to try to use those same passwords in another system (as many users use the same password everywhere, this would be dangerous).

   *
   * <p><b>Warning:</b> This method will produce different output than most other languages do when
   * running on the equivalent input. For cross-language compatibility, use {@link #putString},
   * usually with a charset of UTF-8. For other use cases, use {@code putUnencodedChars}.
   *
   * @since 15.0 (since 11.0 as putString(CharSequence))
   */
  @CanIgnoreReturnValue

SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

     * @param fields the fields to extract from the query log
     * @param tagFieldNames the names of the fields to use as tags
     * @param roleFieldName the name of the field to use for roles
     * @param readingConverter the converter to use for reading values
     * @param normalizer the normalizer to use for normalizing values
     * @return a list of suggest items parsed from the query log
     */

public abstract class TreeTraverser<T> {
  /** Constructor for use by subclasses. */
  public TreeTraverser() {}

  /**
   * Returns a tree traverser that uses the given function to navigate from a node to its children.
   * This is useful if the function instance already exists, or so that you can supply a lambda
   * expressions. If those circumstances don't apply, you probably don't need to use this; subclass

 * try (Response response = call.execute()) {
 * ... // Use the response.
 * }
 * ```
 *
 * You can use a similar block for asynchronous calls:
 *
 * ```java
 * Call call = client.newCall(request);
 * call.enqueue(new Callback() {
 *   public void onResponse(Call call, Response response) throws IOException {
 *     try (ResponseBody responseBody = response.body()) {
 *     ... // Use the response.
 *     }
 *   }
 *

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

If you want something quick to copy and paste, don't use this example, use the last one below.

///

Then, when you create an instance of that `Settings` class (in this case, in the `settings` object), Pydantic will read the environment variables in a case-insensitive way, so, an upper-case variable `APP_NAME` will still be read for the attribute `app_name`.

target="_blank">versionnage sémantique</a>.

Vous pouvez créer des applications de production avec **FastAPI** dès maintenant (et vous le faites probablement depuis un certain temps), vous devez juste vous assurer que vous utilisez une version qui fonctionne correctement avec le reste de votre code.

## Épinglez votre version de `fastapi`

Tout d'abord il faut "épingler" la version de **FastAPI** que vous utilisez à la dernière version dont vous savez