# Body - Multiple Parameters

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

//// tab | Python 3.10+

Events allow you to capture metrics on your application’s HTTP calls. Use events to monitor:

 * The size and frequency of the HTTP calls your application makes. If you’re making too many calls, or your calls are too large, you should know about it!
 * The performance of these calls on the underlying network. If the network’s performance isn’t sufficient, you need to either improve the network or use less of it.

### EventListener

    assertSize(0);
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertSize(3);
  }

  public void testEquals() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    // We know that we have only added non-null Characters.
    Table<String, Integer, Character> hashCopy =
        HashBasedTable.create((Table<String, Integer, ? extends Character>) table);

    LocalCache<?, ?> map = CacheTesting.toLocalCache(cache);

    assertThat(map.segments).hasLength(4);
    // 1 is as low as it goes, not 0. it feels dirty to know this/test this.
    assertEquals(1, map.segments[0].table.length());
    assertEquals(1, map.segments[1].table.length());
    assertEquals(1, map.segments[2].table.length());
    assertEquals(1, map.segments[3].table.length());

    return new RequestBody() {
      @Override public MediaType contentType() {
        return body.contentType();
      }

      @Override public long contentLength() {
        return -1; // We don't know the compressed length in advance!
      }

      @Override public void writeTo(BufferedSink sink) throws IOException {
        BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
        body.writeTo(gzipSink);

      // it. To preserve FIFO order and failure atomicity of rejected execution when the same
      // Runnable is executed more than once, allocate a wrapper that we know is safe to remove by
      // object identity.
      // A data structure that returned a removal handle from add() would allow eliminating this
      // allocation.
      submittedTask =
          new Runnable() {

      // it. To preserve FIFO order and failure atomicity of rejected execution when the same
      // Runnable is executed more than once, allocate a wrapper that we know is safe to remove by
      // object identity.
      // A data structure that returned a removal handle from add() would allow eliminating this
      // allocation.
      submittedTask =
          new Runnable() {

    * Validation even for deeply nested JSON objects.
* <abbr title="also known as: serialization, parsing, marshalling">Conversion</abbr> of input data: coming from the network to Python data and types. Reading from:
    * JSON.
    * Path parameters.
    * Query parameters.
    * Cookies.
    * Headers.
    * Forms.
    * Files.

SNI is not used because it is illegal to use IPs in SNI, and there is no other existing standard format to represent what we need to.
Additionally, using the redirection mechanism reduces the need for clients to know the destination's ztunnel address.

Below shows an example outbound request. The "target" path is what the client sends, while the "actual" path is the real network flow after redirection.

```mermaid
graph LR

 * in any IO with the server. Unlink <tt>InputStream</tt> value less than
 * the one provided will not be returned if it exceeds the end of the file
 * (if this is a problem let us know).
 */
    public long skip( long n ) throws IOException {
        if (n > 0) {
            fp += n;
            return n;
        }
        return 0;
    }