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

/// note | Technical Details

Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded`.

But when the form includes files, it is encoded as `multipart/form-data`. You'll read about handling files in the next chapter.

import org.junit.jupiter.params.provider.ArgumentsSource

/**
 * Tests for round-tripping headers through hpack.
 *
 * TODO: update hpack-test-case with the output of our encoder.
 * This test will hide complementary bugs in the encoder and decoder,
 * We should test that the encoder is producing responses that are
 */
class HpackRoundTripTest : HpackDecodeTestBase() {
  internal class StoriesTestProvider : SimpleProvider() {

	readParts := ReadPartCheckSums(serializedOut)
	expectedChecksums := []string{
		part1Checksum.Encoded,
		part2Checksum.Encoded,
		part3Checksum.Encoded,
	}
	for i, expected := range expectedChecksums {
		if got := readParts[i][ChecksumCRC32C.String()]; got != expected {
			t.Fatalf("want part%dChecksum.Encoded %s, got %s", i+1, expected, got)
		}
	}

Bir [Response Model](../tutorial/response-model.md) deklare ederseniz, FastAPI veriyi Pydantic kullanarak JSON'a serialize etmek için bunu kullanır.

Bir response model deklare etmezseniz, FastAPI [JSON Uyumlu Encoder](../tutorial/encoder.md)'da anlatılan `jsonable_encoder`'ı kullanır ve bunu bir `JSONResponse` içine koyar.

Ayrıca doğrudan bir `JSONResponse` oluşturup döndürebilirsiniz.

/// tip | İpucu

 * \r} or {@code \r\n}, do not include the line separator in each line and do not consider there to
 * be an empty line at the end if the contents are terminated with a line separator.
 *
 * <p>Any {@link ByteSource} containing text encoded with a specific {@linkplain Charset character
 * encoding} may be viewed as a {@code CharSource} using {@link ByteSource#asCharSource(Charset)}.
 *

     *
     * @return the last modified timestamp
     */
    public ZonedDateTime getLastModified() {
        return lastModified;
    }

    /**
     * Returns the base64-encoded ID of the item.
     *
     * @return the encoded ID
     */
    public String getEncodedId() {
        return encodedId;
    }

/// info

Gardez à l'esprit que les dataclasses ne peuvent pas tout ce que peuvent faire les modèles Pydantic.

Vous pourriez donc avoir encore besoin d'utiliser des modèles Pydantic.

Mais si vous avez déjà un ensemble de dataclasses sous la main, c'est une astuce pratique pour les utiliser afin d'alimenter une API Web avec FastAPI. 🤓

///

Wenn Sie kein Responsemodell deklarieren, verwendet FastAPI den `jsonable_encoder`, wie in [JSON-kompatibler Encoder](../tutorial/encoder.md) erläutert, und packt die Daten in eine `JSONResponse`.

Sie könnten auch direkt eine `JSONResponse` erstellen und zurückgeben.

/// tip | Tipp

Si declaras un [Response Model](../tutorial/response-model.md) FastAPI lo usará para serializar los datos a JSON, usando Pydantic.

Si no declaras un response model, FastAPI usará el `jsonable_encoder` explicado en [JSON Compatible Encoder](../tutorial/encoder.md) y lo pondrá en un `JSONResponse`.

También podrías crear un `JSONResponse` directamente y devolverlo.

/// tip | Consejo

/**
 * The first two bytes of each value is a header that includes its tag (field ID) and length.
 */
internal data class DerHeader(
  /**
   * Namespace of the tag.
   *
   * This value is encoded in bits 7 and 8 of the first byte of each value.
   *
   * ```
   * 0b00xxxxxx Universal
   * 0b01xxxxxx Application
   * 0b10xxxxxx Context-Specific
   * 0b11xxxxxx Private
   * ```
   */
  var tagClass: Int,