# Body - Nested Models { #body-nested-models }

With **FastAPI**, you can define, validate, document, and use arbitrarily deeply nested models (thanks to Pydantic).

## List fields { #list-fields }

You can define an attribute to be a subtype. For example, a Python `list`:

{* ../../docs_src/body_nested_models/tutorial001_py310.py hl[12] *}

This will make `tags` be a list, although it doesn't declare the type of the elements of the list.

standard = [
    "fastapi-cli[standard] >=0.0.8",
    # For the test client
    "httpx >=0.23.0,<1.0.0",
    # For templates
    "jinja2 >=3.1.5",
    # For forms and file uploads
    "python-multipart >=0.0.18",
    # To validate email fields
    "email-validator >=2.0.0",
    # Uvicorn with uvloop
    "uvicorn[standard] >=0.12.0",
    # # Settings management
    "pydantic-settings >=2.0.0",
    # # Extra Pydantic data types

     * @return HTML response redirecting to the maintenance page
     */
    @Execute
    @Secured({ ROLE })
    public HtmlResponse reindexOnly(final ActionForm form) {
        validate(form, messages -> {}, this::asIndexHtml);
        verifyToken(this::asIndexHtml);
        if (startReindex(isCheckboxEnabled(form.replaceAliases), isCheckboxEnabled(form.resetDictionaries), form.numberOfShardsForDoc,

    internal var minFreshSeconds = -1
    internal var onlyIfCached: Boolean = false
    internal var noTransform: Boolean = false
    internal var immutable: Boolean = false

    /** Don't accept an unvalidated cached response. */
    fun noCache() = commonNoCache()

    /** Don't store the server's response in any cache. */
    fun noStore() = commonNoStore()

    /**

     * @return HTML response for the web config edit form
     */
    @Execute
    @Secured({ ROLE })
    public HtmlResponse edit(final EditForm form) {
        validate(form, messages -> {}, this::asListHtml);
        final String id = form.id;
        webConfigService.getWebConfig(id).ifPresent(entity -> {
            copyBeanToBean(entity, form, copyOp -> {

	claims["exp"] = time.Now().UTC().Add(defaultExpiryDuration).Unix() // update with new expiry.
	return nil
}

const (
	audClaim = "aud"
	azpClaim = "azp"
)

// Validate - validates the id_token.
func (r *Config) Validate(ctx context.Context, arn arn.ARN, token, accessToken, dsecs string, claims map[string]any) error {
	jp := new(jwtgo.Parser)
	jp.ValidMethods = []string{
		"RS256", "RS384", "RS512",

		fmt.Fprintln(os.Stderr, "reading input:", err)
	}
	fmt.Printf("%d\n", count)
	// Output: 15
}

// Use a Scanner with a custom split function (built by wrapping ScanWords) to validate
// 32-bit decimal input.
func ExampleScanner_custom() {
	// An artificial input source.
	const input = "1234 5678 1234567901234567890"
	scanner := bufio.NewScanner(strings.NewReader(input))

import org.codelibs.core.timer.TimeoutManager;

/**
 * Utility class for handling {@link File}.
 * <p>
 * <strong>SECURITY NOTE:</strong> When accepting file paths from untrusted sources,
 * always validate them using {@link #isPathSafe(Path, Path)} to prevent path traversal attacks.
 * Methods that accept path strings do not perform automatic validation to maintain backward compatibility.
 * </p>
 *
 * @author higa
 */

		}
		return false, azureToObjectError(err, az.Bucket, az.Prefix)
	}

	return len(resp.Segment.BlobItems) > 0, nil
}

type azureConf struct {
	madmin.TierAzure
}

func (conf azureConf) Validate() error {
	switch {
	case conf.AccountName == "":
		return errors.New("the account name is required")

		Enable     bool `json:"enable"`
		SkipVerify bool `json:"skipVerify"`
	} `json:"tls"`
	QueueDir   string `json:"queueDir"`
	QueueLimit uint64 `json:"queueLimit"`
}

// Validate NSQArgs fields
func (n NSQArgs) Validate() error {
	if !n.Enable {
		return nil
	}

	if n.NSQDAddress.IsEmpty() {
		return errors.New("empty nsqdAddress")
	}

	if n.Topic == "" {
		return errors.New("empty topic")
	}