{* ../../docs_src/header_param_models/tutorial001_an_py310.py hl[9:14,18] *}

**FastAPI** will **extract** the data for **each field** from the **headers** in the request and give you the Pydantic model you defined.

## Check the Docs { #check-the-docs }

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>

type Source struct {
	Host      string `json:"host"`
	Port      string `json:"port"`
	UserAgent string `json:"userAgent"`
}

// Event represents event notification information defined in
// http://docs.aws.amazon.com/AmazonS3/latest/dev/notification-content-structure.html.
type Event struct {
	EventVersion      string            `json:"eventVersion"`
	EventSource       string            `json:"eventSource"`

	defer cancel()

	err := obj.MakeBucket(ctx, bucket, MakeBucketOptions{})
	if err != nil {
		t.Fatalf("Failed to make a bucket %v", err)
	}

	// Object for test case 1 - No StorageClass defined, no MetaData in PutObject
	object1 := "object1"
	globalStorageClass.Update(storageclass.Config{
		RRS: storageclass.StorageClass{
			Parity: 2,
		},
		Standard: storageclass.StorageClass{
			Parity: 4,

 * specified the JVM flag {@code -XX:+DisableExplicitGC}. But in practice, it works very well for
 * ordinary tests.
 *
 * <p>Failure of the expected event to occur within an implementation-defined "reasonable" time
 * period or an interrupt while waiting for the expected event will result in a {@link
 * RuntimeException}.
 *
 * <p>Here's an example that tests a {@code finalize} method:
 *
 * {@snippet :

		return false
	}
	if fi1.Mode() != fi2.Mode() {
		return false
	}
	return fi1.Size() == fi2.Size()
}

// DirectioAlignSize - DirectIO alignment needs to be 4K. Defined here as
// directio.AlignSize is defined as 0 in MacOS causing divide by 0 error.
const DirectioAlignSize = 4096

// CopyAligned - copies from reader to writer using the aligned input

/**
 * Test class for NtStatus constants
 */
@DisplayName("NtStatus Tests")
class NtStatusTest {

    @Test
    @DisplayName("Should define well-known NT status constants")
    void testWellKnownStatusConstants() {
        // Verify important NT status constants are defined
        assertEquals(0x00000000, NtStatus.NT_STATUS_SUCCESS);
        assertEquals((int) 0xC0000022L, NtStatus.NT_STATUS_ACCESS_DENIED);

   * of their elements."
   *
   * </blockquote>
   */
  RESTRICTS_ELEMENTS,

  /**
   * Indicates that a collection has a well-defined ordering of its elements. The ordering may
   * depend on the element values, such as a {@link SortedSet}, or on the insertion ordering, such

	// Canceling the context will cause the context cancellation error to be returned.
	responses <-chan Response
	cancel    context.CancelCauseFunc

	// Requests sent to the server.
	// If the handler is defined with 0 incoming capacity this will be nil.
	// Channel *must* be closed to signal the end of the stream.
	// If the request context is canceled, the stream will no longer process requests.

            // Act & Assert - getOpnum is inherited from SamrConnect2
            assertDoesNotThrow(() -> msg.getOpnum());
            assertEquals(0x39, msg.getOpnum(), "getOpnum should return 0x39 as defined in SamrConnect2");
        }
    }

        """
        The OAuth 2 specification doesn't define the challenge that should be used,
        because a `Bearer` token is not really the only option to authenticate.

        But declaring any other authentication challenge would be application-specific
        as it's not defined in the specification.

        For practical reasons, this method uses the `Bearer` challenge by default, as