# Background Tasks - `BackgroundTasks`

You can declare a parameter in a *path operation function* or dependency function with the type `BackgroundTasks`, and then you can use it to schedule the execution of background tasks after the response is sent.

You can import it directly from `fastapi`:

```python
from fastapi import BackgroundTasks
```

    - tutorial/handling-errors.md
    - tutorial/path-operation-configuration.md
    - tutorial/encoder.md
    - tutorial/body-updates.md
    - Dependencies:
      - tutorial/dependencies/index.md
      - tutorial/dependencies/classes-as-dependencies.md
      - tutorial/dependencies/sub-dependencies.md
      - tutorial/dependencies/dependencies-in-path-operation-decorators.md
      - tutorial/dependencies/global-dependencies.md

$ uvicorn main:my_awesome_api --reload

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

</div>

### Шаг 3: определите *операцию пути (path operation)*

#### Путь (path)

"Путь" это часть URL, после первого символа `/`, следующего за именем домена.

Для URL:

```
https://example.com/items/foo
```

...путь выглядит так:

                        break;
                    default:
                        throw new SmbException("Invalid operation for " + service + " service");
                    }
                    break;
                default:
                    throw new SmbException("Invalid operation for " + service + " service" + request);
                }
            }
            request.tid = tid;

    /**
     * Deletes all crawling sessions and their parameters except for the specified active sessions.
     * This is a cleanup operation that removes inactive session data while preserving active ones.
     *
     * @param activeSessionId a set of session IDs to preserve during the cleanup operation
     */
    public void deleteOldSessions(final Set<String> activeSessionId) {
        final List<CrawlingInfo> activeSessionList =

   * An object that holds the final result of an asynchronous {@link ClosingFuture} operation and
   * allows the user to close all the closeable objects that were captured during it for later
   * closing.
   *
   * <p>The asynchronous operation will have completed before this object is created.
   *
   * @param <V> the type of the value of a successful operation
   * @see ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)

   *     no change will be made.
   * @return the count of the element before the operation; possibly zero
   * @throws IllegalArgumentException if {@code occurrences} is negative, or if this operation would
   *     result in more than {@link Integer#MAX_VALUE} occurrences of the element

# Request Parameters

Here's the reference information for the request parameters.

These are the special functions that you can put in *path operation function* parameters or dependency functions with `Annotated` to get data from the request.

It includes:

* `Query()`
* `Path()`
* `Body()`
* `Cookie()`
* `Header()`
* `Form()`
* `File()`

You can import them all directly from `fastapi`:

```python

### DurationSeconds

The duration, in seconds. The value can range from 900 seconds (15 minutes) up to 365 days. If value is higher than this setting, then operation fails. By default, the value is set to 3600 seconds.

| Params        | Value                                              |
| :--           | :--                                                |

# `Request` class

You can declare a parameter in a *path operation function* or dependency to be of type `Request` and then you can access the raw request object directly, without any validation, etc.

You can import it directly from `fastapi`:

```python
from fastapi import Request
```

/// tip