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

### Download and Install/Run

Fess 15.3 is now available and can be downloaded on the [Releases page](https://github.com/codelibs/fess/releases "download"). Downloads come in 3 flavors: deb, rpm, zip.

The following commands show how to use the zip download:

    $ unzip fess-15.3.x.zip
    $ cd fess-15.3.x
    $ ./bin/fess

For more details, see the [Installation Guide](https://fess.codelibs.org/15.3/install/index.html).

### Docker

# Note, an invalid sub-interface name will lead to an obscure error, e.g.:
# "The filename, directory name, or volume label syntax is incorrect."
# In such cases, check that the name of the sub-interface is valid:
# `netsh interface show interface`
RUN netsh interface ipv4 set subinterface \"vEthernet (Ethernet)\" mtu=1460 store=persistent

RUN md C:\TEMP
RUN md C:\TMP

# Install 7-Zip.

		return closestCommands
	}

	// Register all commands.
	registerCommand(serverCmd)
	registerCommand(fmtGenCmd)

	// Set up app.
	cli.HelpFlag = cli.BoolFlag{
		Name:  "help, h",
		Usage: "show help",
	}
	cli.VersionPrinter = printMinIOVersion

	app := cli.NewApp()
	app.Name = name
	app.Author = "MinIO, Inc."
	app.Version = ReleaseTag
	app.Usage = "High Performance Object Storage"

So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.

That documentation will show up in the Swagger UI at `/docs` in your API, and it will let external developers know how to build the *external API*.

If you have an old FastAPI app with Pydantic v1, here I'll show you how to migrate it to Pydantic v2, and the **features in FastAPI 0.119.0** to help you with a gradual migration.

## Official Guide { #official-guide }

Pydantic has an official <a href="https://docs.pydantic.dev/latest/migration/" class="external-link" target="_blank">Migration Guide</a> from v1 to v2.

We just scratched the surface, but you already get the idea of how it all works.

Try changing the line with:

```Python
    return {"item_name": item.name, "item_id": item_id}
```

...from:

```Python
        ... "item_name": item.name ...
```

...to:

```Python
        ... "item_price": item.price ...
```

...and see how your editor will auto-complete the attributes and know their types:

.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...

                Customize the function used to generate unique IDs for the *path
                operations* shown in the generated OpenAPI.

                This is particularly useful when automatically generating clients or
                SDKs for your API.

                Read more about it in the
                [FastAPI docs about how to Generate Clients](https://fastapi.tiangolo.com/advanced/generate-clients/#custom-generate-unique-id-function).

## 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_py39.py hl[16,19] *}