## Lifespan { #lifespan }

You can define this *startup* and *shutdown* logic using the `lifespan` parameter of the `FastAPI` app, and a "context manager" (I'll show you what that is in a second).

Let's start with an example and then see it in detail.

We create an async function `lifespan()` with `yield` like this:

{* ../../docs_src/events/tutorial003_py310.py hl[16,19] *}

		if cs[j].before == "*" && cs[i].before != "*" {
			return true
		}
		if cs[j].after == "*" && cs[i].after != "*" {
			return true
		}
		return false
	})

	for _, c := range cs {
		// show warning message the callback name already exists
		if idx := getRIndex(names, c.name); idx > -1 && !c.replace && !c.remove && !cs[idx].remove {

labels.virtual_host_value=Virtual Host
labels.append_query_param_enabled=Append Search Parameters
labels.login_required=Login Required
labels.result_collapsed=Collapse Duplicate Results
labels.login_link=Show Login Link
labels.thumbnail=Show Thumbnail
labels.ignore_failure_type=Ignore Failure Types
labels.failure_count_threshold=Failure Count Threshold
labels.popular_word_word_enabled=Popular Word Response
labels.supported_search_web=Web

.nav-link:hover {\n  border-color: #56606a;\n}\n\n.dark-mode .nav-tabs .nav-item.show .nav-link,\n.dark-mode .nav-tabs .nav-link.active {\n  background-color: #343a40;\n  border-color: #56606a #56606a transparent #56606a;\n  color: #fff;\n}\n\n.dark-mode .nav-tabs.flex-column .nav-item.show .nav-link.active, .dark-mode .nav-tabs.flex-column .nav-item.show .nav-link:focus, .dark-mode .nav-tabs.flex-column .nav-item.show .nav-link:hover,\n.dark-mode .nav-tabs.flex-column .nav-link.active,\n.dark-mode...

![Interceptors Diagram](../assets/images/******@****.***)

### Application Interceptors

Interceptors are registered as either _application_ or _network_ interceptors. We'll use the `LoggingInterceptor` defined above to show the difference.

Register an _application_ interceptor by calling `addInterceptor()` on `OkHttpClient.Builder`:

```java
OkHttpClient client = new OkHttpClient.Builder()
    .addInterceptor(new LoggingInterceptor())

padding-y:0.25rem;--bs-btn-padding-x:0.5rem;--bs-btn-font-size:0.875rem;--bs-btn-border-radius:var(--bs-border-radius-sm)}.fade{transition:opacity .15s linear}@media (prefers-reduced-motion:reduce){.fade{transition:none}}.fade:not(.show){opacity:0}.collapse:not(.show){display:none}.collapsing{height:0;overflow:hidden;transition:height .35s ease}@media (prefers-reduced-motion:reduce){.collapsing{transition:none}}.collapsing.collapse-horizontal{width:0;height:auto;transition:width .35s ease}@media...

{% endfor %}

</div>

I'm the creator of **FastAPI**. You can read more about that in [Help FastAPI - Get Help - Connect with the author](help-fastapi.md#connect-with-the-author).

...But here I want to show you the community.

---

**FastAPI** receives a lot of support from the community. And I want to highlight their contributions.

These are the people that:

And the spec says that the fields have to be named like that. So `user-name` or `email` wouldn't work.

But don't worry, you can show it as you wish to your final users in the frontend.

And your database models can use any other names you want.

        int length = 32;

        Hexdump.hexdump(ps, data, offset, length);
        String output = baos.toString();

        assertNotNull(output);
        // Should start at offset 0 in display but show data from offset 16
        assertTrue(output.contains("00000:"));
        // First byte should be 0x10 (16 in decimal)
        assertTrue(output.contains(" 10 11 12"));
    }

    @Test

                etc.

                It will be used for:

                * Documentation: the generated OpenAPI (and the UI at `/docs`) will
                    show it as the response (JSON Schema).
                * Serialization: you could return an arbitrary object and the
                    `response_model` would be used to serialize that object into the