<!--
            Some tests need reflective access to the internals of these packages. It is only the
            tests themselves and not the code being tested that needs that access, though there's no
            obvious way to ensure that.

            We could consider arranging things so that only the tests we know need this would get
            the add-opens. Right now that doesn't seem worth the effort, though.
        -->

        <!--
            Some tests need reflective access to the internals of these packages. It is only the
            tests themselves and not the code being tested that needs that access, though there's no
            obvious way to ensure that.

            We could consider arranging things so that only the tests we know need this would get
            the add-opens. Right now that doesn't seem worth the effort, though.
        -->

      for (int insertion = 0; insertion < totalInsertions; insertion++) {
        RandomHasherAction.pickAtRandom(random).performAction(random, sinksAndControl);
      }
      // We need to ensure that at least 4 bytes have been put into the hasher or else
      // Hasher#hash will throw an ISE.
      int intToPut = random.nextInt();
      for (Hasher hasher : sinksAndControl) {

	assert.Equal(t, len(fds), 1)
	// in theory we should close the fd, but it's just a test..

	assert.Equal(t, m.Payload.(*zdsapi.WorkloadRequest_Add).Add.Uid, uid)
	// send ack so the server doesn't wait for us.
	sendAck(ztunClient)

	// second message should be the snap sent message
	m, fds = readRequest(t, ztunClient)
	assert.Equal(t, len(fds), 0)

But whenever you need them and go and learn them, know that you can already use them directly in **FastAPI**.

### Pydantic v1 `regex` instead of `pattern`

Before Pydantic version 2 and before FastAPI 0.100.0, the parameter was called `regex` instead of `pattern`, but it's now deprecated.

You could still see some code using it:

//// tab | Python 3.10+ Pydantic v1

# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

	for _, c := range s {
		if c < 0x80 && c != 0x00 {
			b = append(b, byte(c))
		}
	}
	return string(b)
}

type parser struct {
	err error // Last error seen
}

type formatter struct {
	err error // Last error seen
}

// parseString parses bytes as a NUL-terminated C-style string.
// If a NUL byte is not found then the whole slice is returned as a string.
func (*parser) parseString(b []byte) string {

}

func (p *PodNetnsProcFinder) FindNetnsForPods(pods map[types.UID]*corev1.Pod) (PodToNetns, error) {
	/*
		for each process, find its netns inode,
		if we already seen the inode, skip it
		if we haven't seen the inode, check the process cgroup and see if we
		can extract a pod uid from it.
		if we can, open the netns, and save a map of uid->netns-fd
	*/

	podUIDNetns := make(PodToNetns)
	netnsObserved := sets.New[uint64]()

# Behind a Proxy

In some situations, you might need to use a **proxy** server like Traefik or Nginx with a configuration that adds an extra path prefix that is not seen by your application.

In these cases you can use `root_path` to configure your application.

The `root_path` is a mechanism provided by the ASGI specification (that FastAPI is built on, through Starlette).

The `root_path` is used to handle these specific cases.

	needHeaderOffset := f.headerOffset == int64(^uint32(0))

	// Best effort to find what we need.
	// Other zip authors might not even follow the basic format,
	// and we'll just ignore the Extra content in that case.
	var modified time.Time
parseExtras:
	for extra := readBuf(f.Extra); len(extra) >= 4; { // need at least tag and size
		fieldTag := extra.uint16()
		fieldSize := int(extra.uint16())