// Test default values
        assertFalse(config.isUseRDMA(), "RDMA should be disabled by default");
        assertEquals("auto", config.getRdmaProvider(), "Default provider should be auto");
        assertEquals(8192, config.getRdmaReadWriteThreshold(), "Default threshold should be 8KB");
        assertEquals(65536, config.getRdmaMaxSendSize(), "Default max send size should be 64KB");

```

This will validate the data, show a clear error when the data is not valid, and document the parameter in the OpenAPI schema *path operation*.

### `Query` as the default value or in `Annotated` { #query-as-the-default-value-or-in-annotated }

Keep in mind that when using `Query` inside of `Annotated` you cannot use the `default` parameter for `Query`.

     *
     * @return timeout for establishing a socket connection, in milliseconds
     */
    int getConnTimeout();

    /**
     * Property {@code jcifs.smb.client.sessionTimeout} (int, default 35000)
     *
     *
     * @return timeout for SMB sessions, in milliseconds
     */
    int getSessionTimeout();

    /**
     *

Your response model could have default values, like:

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (or `str | None = None` in Python 3.10) has a default of `None`.
* `tax: float = 10.5` has a default of `10.5`.
* `tags: List[str] = []` has a default of an empty list: `[]`.

		if _, err := config.LookupSite(s[config.SiteSubSys][config.Default], s[config.RegionSubSys][config.Default]); err != nil {
			return err
		}
	case config.APISubSys:
		if _, err := api.LookupConfig(s[config.APISubSys][config.Default]); err != nil {
			return err
		}
	case config.BatchSubSys:
		if _, err := batch.LookupConfig(s[config.BatchSubSys][config.Default]); err != nil {
			return err
		}

Python will complain if you put a value with a "default" before a value that doesn't have a "default".

But you can re-order them, and have the value without a default (the query parameter `q`) first.

It doesn't matter for **FastAPI**. It will detect the parameters by their names, types and default declarations (`Query`, `Path`, etc), it doesn't care about the order.

    /** The maximum cached content size in bytes. Default is 1MB. */
    protected long maxCachedContentSize = 1024L * 1024L; // 1MB

    /** The access timeout in seconds. Default is null (no timeout). */
    protected Integer accessTimeout = null; // seconds

    /** The maximum content length in bytes. Default is null (no limit). */
    protected Long maxContentLength = null;

    /**

<img src="/img/tutorial/extending-openapi/image04.png">

## Change Default Swagger UI Parameters { #change-default-swagger-ui-parameters }

FastAPI includes some default configuration parameters appropriate for most of the use cases.

It includes these default configurations:

{* ../../fastapi/openapi/docs.py ln[8:23] hl[17:23] *}

* Data validation
* Automatic documentation

## Defaults { #defaults }

As query parameters are not a fixed part of a path, they can be optional and can have default values.

In the example above they have default values of `skip=0` and `limit=10`.

So, going to the URL:

```
http://127.0.0.1:8000/items/
```

    /**
     * Default maximum number of receive credits
     */
    public static final int DEFAULT_RECEIVE_CREDIT_MAX = 255;

    /**
     * Default target number of send credits
     */
    public static final int DEFAULT_SEND_CREDIT_TARGET = 32;

    /**
     * Default maximum receive size (8KB)
     */
    public static final int DEFAULT_MAX_RECEIVE_SIZE = 8192;