`Header` is a "sister" class of `Path`, `Query` and `Cookie`. It also inherits from the same common `Param` class.

But remember that when you import `Query`, `Path`, `Header`, and others from `fastapi`, those are actually functions that return special classes.

///

/// info

To declare headers, you need to use `Header`, because otherwise the parameters would be interpreted as query parameters.

///

## Automatic conversion { #automatic-conversion }

 * It extends HtmlTransformer and provides functionality to:
 * </p>
 * <ul>
 *     <li>Specify a base directory for storing files.</li>
 *     <li>Generate file paths from URLs, replacing special characters.</li>
 *     <li>Handle duplicated file paths by appending a counter.</li>
 *     <li>Store the file path in the result data.</li>
 *     <li>Retrieve the stored file as a File object.</li>
 * </ul>
 *
 * <p>

You can see the required headers in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Forbid Extra Headers { #forbid-extra-headers }

In some special use cases (probably not very common), you might want to **restrict** the headers that you want to receive.

You can use Pydantic's model configuration to `forbid` any `extra` fields:

            assertEquals(errorMessage, e.getMessage());
            assertTrue(e instanceof LdapConfigurationException);
        }
    }

    public void test_specialCharactersInMessage() {
        // Test with special characters in message
        String message = "LDAP error: \"Invalid <config>\" & 'bad chars' @ #$%^&*()";
        LdapConfigurationException exception = new LdapConfigurationException(message);

        StorageException exception = new StorageException(message);
        assertEquals(message, exception.getMessage());
    }

    public void test_specialCharactersInMessage() {
        // Test with special characters in message
        String message = "Storage error: \n\t\r\"'<>&";
        StorageException exception = new StorageException(message);

        assertEquals(message, exception.getMessage());
    }

    * `200` is the default status code, which means everything was "OK".
    * Another example would be `201`, "Created". It is commonly used after creating a new record in the database.
    * A special case is `204`, "No Content".  This response is used when there is no content to return to the client, and so the response must not have a body.

        assertNull(result1);
        assertNull(result2);
    }

    @Test
    void testGetSecurityWithSpecialCharactersInSecurityDescriptor() throws Exception {
        // Test with security descriptor containing special byte values but invalid structure
        srvsvc.ShareInfo502 info502 = new srvsvc.ShareInfo502();
        byte[] specialBytes = new byte[] { 0, -1, 127, -128, 64 };
        info502.security_descriptor = specialBytes;

/**
 * Tests for the HttpHeaders class.
 *
 * @author Kurt Alfred Kluever
 */
@NullUnmarked
public class HttpHeadersTest extends TestCase {

  public void testConstantNameMatchesString() throws Exception {
    // Special case some of the weird HTTP Header names...
    ImmutableBiMap<String, String> specialCases =
        ImmutableBiMap.<String, String>builder()
            .put("CDN_LOOP", "CDN-Loop")
            .put("ETAG", "ETag")

///

## About "Form Fields" { #about-form-fields }

The way HTML forms (`<form></form>`) sends the data to the server normally uses a "special" encoding for that data, it's different from JSON.

**FastAPI** will make sure to read that data from the right place instead of JSON.

/// note | Technical Details

        assertEquals(message, exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withSpecialCharacters() {
        // Test with special characters in message
        String message = "Search not supported: \n\t!@#$%^&*(){}[]|\\:;\"'<>,.?/~`";
        UnsupportedSearchException exception = new UnsupportedSearchException(message);