## About third party integrations

In this example we are using the OAuth2 "password" flow.

This is appropriate when we are logging in to our own application, probably with our own frontend.

Because we can trust it to receive the `username` and `password`, as we control it.

   * safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * <p>This method is not type-safe, as it may be called on a map with keys that are not mutually
   * comparable.
   *
   * @throws ClassCastException if the keys in {@code map} are not mutually comparable
   * @throws NullPointerException if any key or value in {@code map} is null

	Metrics bool   `msg:"m"`
	NoOp    bool   `msg:"np"`
}

// DiskInfo is an extended type which returns current
// disk usage per path.
// The above means that any added/deleted fields are incompatible.
//
// The above means that any added/deleted fields are incompatible.
//
//msgp:tuple DiskInfo
type DiskInfo struct {
	Total      uint64
	Free       uint64
	Used       uint64
	UsedInodes uint64
	FreeInodes uint64

/// tip

All this might seem contrived. And it might not be very clear how is it useful yet.

These examples are intentionally simple, but show how it all works.

In the chapters about security, there are utility functions that are implemented in this same way.

If you understood all this, you already know how those utility tools for security work underneath.

### Return the error

After detecting that the credentials are incorrect, return an `HTTPException` with a status code 401 (the same returned when no credentials are provided) and add the header `WWW-Authenticate` to make the browser show the login prompt again:

And Pydantic's `Field` returns an instance of `FieldInfo` as well.

`Body` also returns objects of a subclass of `FieldInfo` directly. And there are others you will see later that are subclasses of the `Body` class.

Remember that when you import `Query`, `Path`, and others from `fastapi`, those are actually functions that return special classes.

///

/// tip

This directory contains the helm chart _sources_ which are versioned, built and pushed to following helm
repositories with each Istio release.  If you want to make changes to Istio helm charts, you're in the
right place.

If you want to _install_ Istio with Helm, instead please [follow the Helm installation docs here](https://istio.io/latest/docs/setup/install/helm/).

Charts in this folder are published to the following Helm repos:

 *
 * <p>Except as noted, the orderings returned by the factory methods of this class are serializable
 * if and only if the provided instances that back them are. For example, if {@code ordering} and
 * {@code function} can themselves be serialized, then {@code ordering.onResultOf(function)} can as
 * well.
 *
 * <h3>Java 8+ users</h3>
 *
 * <p>If you are using Java 8+, this class is now obsolete. Most of its functionality is now

    * `200` is the default status code, which means everything was "OK".
    * Another example would be `201`, "Created". It is commonly used after creating a new record in the database.
    * A special case is `204`, "No Content".  This response is used when there is no content to return to the client, and so the response must not have a body.

{* ../../docs_src/advanced_middleware/tutorial002.py hl[2,6:8] *}

The following arguments are supported:

* `allowed_hosts` - A list of domain names that should be allowed as hostnames. Wildcard domains such as `*.example.com` are supported for matching subdomains. To allow any hostname either use `allowed_hosts=["*"]` or omit the middleware.