// 2. Normalize, from bufferB to bufferA.
  val normalized = normalizeNfc(bufferB.readUtf8())
  bufferA.writeUtf8(normalized)

  // 3. For each label, convert/validate Punycode.
  val decoded = Punycode.decode(bufferA.readUtf8()) ?: return null

  // 4.1 Validate.

  // Must be NFC.
  if (decoded != normalizeNfc(decoded)) return null

  // TODO: Must not begin with a combining mark.

```

</div>

Then go to the `/docs` UI, you will see that **FastAPI** is using these **models** to **document** the API, and it will use them to **serialize** and **validate** the data too.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Update the App with Multiple Models { #update-the-app-with-multiple-models }

t:"La lunghezza della risposta deve essere maggiore di ",notConfirmed:"Il valore non è stato confermato.",badDomain:"Il dominio inserito non è corretto.",badUrl:"L' URL inserito non è valido",badCustomVal:"I valori inseriti non sono validi",andSpaces:" e spazi ",badInt:"Il numero inserito non è valido",badSecurityNumber:"Il numero di sicurezza inserito non è valido",badUKVatAnswer:"La Partita IVA (VAT) inserita non è valida nel Regno Unito",badStrength:"La password...

## Results { #results }

With just that Python type declaration, **FastAPI** will:

* Read the body of the request as JSON.
* Convert the corresponding types (if needed).
* Validate the data.
    * If the data is invalid, it will return a nice and clear error, indicating exactly where and what was the incorrect data.
* Give you the received data in the parameter `item`.

			// mime package in MinIO, which correctly encodes strings with fixed B/Q encodings,
			// avoiding S3’s heuristic-driven issues.
			//
			// For MinIO developers, decode S3 metadata with mime.WordDecoder, validate outputs,
			// report encoding bugs to AWS, and use ASCII-only metadata to ensure reliable S3 API
			// compatibility.
			if needsMimeEncoding(v) {

        setTreeIdMethod.invoke(response, 12345);

        // When
        int tid = response.getTid();

        // Then
        assertEquals(12345, tid);
    }

    @Test
    @DisplayName("Should validate TID correctly")
    void testIsValidTid() throws Exception {
        // Test invalid TID (-1)
        Method setTreeIdMethod = ServerMessageBlock2.class.getDeclaredMethod("setTreeId", int.class);

	encrypt.SseEncryptionContext: true,
	encrypt.SseCustomerAlgorithm: true,
	encrypt.SseCustomerKey:       true,
	encrypt.SseCustomerKeyMD5:    true,
}

// checkPostPolicy - apply policy conditions and validate input values.
// Note that content-length-range is checked in the API handler function PostPolicyBucketHandler.
// formValues is the already-canonicalized form values from the POST request.

		return s.Delete(ctx, volume, path, DeleteOptions{
			Recursive: false,
			Immediate: false,
		})
	}

	volumeDir, err := s.getVolDir(volume)
	if err != nil {
		return err
	}

	// Validate file path length, before reading.
	filePath := pathJoin(volumeDir, path)
	if err = checkPathLength(filePath); err != nil {
		return err
	}

	var legacyJSON bool

	for i := range parts {
		if errs[i] == nil {
			if parts[i].Name == objectName {
				t.Errorf("path traversal allowed to allow writing to minioMetaBucket: %s", instanceType)
			}
		}
	}
}

// Tests validate bucket name.
func TestIsValidBucketName(t *testing.T) {
	testCases := []struct {
		bucketName string
		shouldPass bool
	}{
		// cases which should pass the test.
		// passing in valid bucket names.

	// Setup and capture test results for directory with files and symlink.
	testResults = append(testResults, setupTestReadDirSymlink(t)...)

	// Remove all dirs once tests are over.
	defer teardown(testResults)

	// Validate all the results.
	for _, r := range testResults {
		if entries, err := readDir(r.dir); err != nil {
			t.Fatal("failed to run test.", err)
		} else {
			// Keep entries sorted for easier comparison.