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: `[]`.

     *
     * @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();

    /**
     *

        // 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");

        assertEquals(4, config.getMaxChannels(), "Default max channels should be 4");
        assertEquals(1, config.getChannelBindingPolicy(), "Default binding policy should be preferred");
        assertEquals("adaptive", config.getLoadBalancingStrategy(), "Default strategy should be adaptive");
        assertEquals(10, config.getChannelHealthCheckInterval(), "Default health check interval should be 10");
    }

```

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`.

* Specific HTTP headers or all of them with the wildcard `"*"`.

{* ../../docs_src/cors/tutorial001.py hl[2,6:11,13:19] *}


The default parameters used by the `CORSMiddleware` implementation are restrictive by default, so you'll need to explicitly enable particular origins, methods, or headers, in order for browsers to be permitted to use them in a Cross-Domain context.

The following arguments are supported:

* 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/
```

///

## Overriding the defaults { #overriding-the-defaults }

Using the information above, you can use the same utility function to generate the OpenAPI schema and override each part that you need.

    /** Whether to convert DFS paths to FQDN */
    protected boolean dfsConvertToFqdn;
    /** Default logon share */
    protected String logonShare;
    /** Default domain for authentication */
    protected String defaultDomain;
    /** Default username for authentication */
    protected String defaultUserName;
    /** Default password for authentication */
    protected String defaultPassword;
    /** NetBIOS hostname */

                setDefaultProperties();
            }
        } catch (IOException e) {
            logger.warn("Failed to load system.properties, using defaults", e);
            setDefaultProperties();
        }
    }

    private void setDefaultProperties() {
        // Set default test properties
        setProperty("fess.version", "99.99.99");
    }