# Header Parameter Models { #header-parameter-models }

If you have a group of related **header parameters**, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

				return nil, err
			}
			continue
		}
		data, _ = json.Marshal(cfg)
		break
	}
	if osIsPermission(err) {
		logger.Info("Older config found but is not readable %s, proceeding to read config from other places", err)
	}
	if osIsNotExist(err) || osIsPermission(err) || len(data) == 0 {
		data, err = readConfig(GlobalContext, objAPI, configFile)
		if err != nil {
			// when config.json is not found, then we freshly initialize.

 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingSet<E extends @Nullable Object> extends ForwardingCollection<E>
    implements Set<E> {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingSet() {}

  @Override
  protected abstract Set<E> delegate();

  @Override

# Cookie Parameter Models { #cookie-parameter-models }

If you have a group of **cookies** that are related, you can create a **Pydantic model** to declare them. 🍪

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

/// tip

The content of each of these strings can have any format, but should not contain spaces.

These scopes represent "permissions".

In OpenAPI (e.g. the API docs), you can define "security schemes".

When one of these security schemes uses OAuth2, you can also declare and use scopes.

Each "scope" is just a string (without spaces).

dependencies and the dependencies are solved based on the declared types. So, it's not possible to declare more than one "component" that provides a certain type.

Routes are declared in a single place, using functions declared in other places (instead of using decorators that can be placed right on top of the function that handles the endpoint). This is closer to how Django does it than to how Flask (and Starlette) does it. It separates in the code things that are relatively tightly coupled....

 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingSet<E extends @Nullable Object> extends ForwardingCollection<E>
    implements Set<E> {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingSet() {}

  @Override
  protected abstract Set<E> delegate();

  @Override

 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingMapEntry<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingObject implements Map.Entry<K, V> {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingMapEntry() {}

  @Override
  protected abstract Entry<K, V> delegate();

  @Override

     */
    @Nonnull
    Optional<Options> options();

    /**
     * This method returns "verbose" option value derived from multiple places: CLI options, but also CI detection,
     * if applicable.
     */
    default boolean effectiveVerbose() {
        return options().isPresent() && options().orElseThrow().verbose().orElse(false)

The correct place is:

* In the key `content`, that has as value another JSON object (`dict`) that contains:
    * A key with the media type, e.g. `application/json`, that contains as value another JSON object, that contains:
        * A key `schema`, that has as the value the JSON Schema from the model, here's the correct place.