For example, this custom validator checks that the item ID starts with `isbn-` for an <abbr title="International Standard Book Number">ISBN</abbr> book number or with `imdb-` for an <abbr title="Internet Movie Database: a website with information about movies">IMDB</abbr> movie URL ID:

{* ../../docs_src/query_params_str_validations/tutorial015_an_py310.py hl[5,16:19,24] *}

/// info

This is available with Pydantic version 2 or above. 😎

///

video/mpeg                     mpeg mpg mpe     # MPEG Movie File
video/quicktime                qt mov           # Quicktime Movie File
video/x-ms-asf                 asf asx          # Windows Media  File
video/x-msvideo                avi              # AVI Movie File

            logger.log(format("ECL0017", e.getMessage()), e);
        }
    }

    /**
     * Moves the result set to the next position.
     *
     * @param resultSet
     *            The result set. Must not be {@literal null}.
     * @return Whether the result set successfully moved to the next position.
     */
    public static boolean next(final ResultSet resultSet) {

            skipMe = new ArrayList<>(3);
          }
          if (!foundAndRemovedExactReference(skipMe, moved.toTrickle)) {
            forgetMeNot.add(moved.toTrickle);
          }
          if (!foundAndRemovedExactReference(forgetMeNot, moved.replaced)) {
            skipMe.add(moved.replaced);
          }
        }
        cursor--;
        nextCursor--;

    /**
     * Copies properties from one Bean to another Bean.
     *
     * @param src The source Bean. Must not be {@literal null}.
     * @param dest The destination Bean. Must not be {@literal null}.
     */
    public static void copyBeanToBean(final Object src, final Object dest) {
        copyBeanToBean(src, dest, DEFAULT_OPTIONS);
    }

    /**
     * Copies properties from one Bean to another Bean.

    protected static final int DEFAULT_BUF_SIZE = 4096;

    // ////////////////////////////////////////////////////////////////
    // from InputStream to OutputStream
    //
    /**
     * Copies from an input stream to an output stream.
     * <p>
     * Neither the input stream nor the output stream is closed.
     * </p>
     *
     * @param in the input stream (must not be {@literal null})

				"application/vnd.minisoft-hp3000-save",
				"application/vnd.mitsubishi.misty-guard.trustweb",
				"application/vnd.mobius.daf",
				"application/vnd.mobius.dis",
				"application/vnd.mobius.mbk",
				"application/vnd.mobius.mqy",
				"application/vnd.mobius.msl",
				"application/vnd.mobius.plc",
				"application/vnd.mobius.txf",
				"application/vnd.mophun.application",
				"application/vnd.mophun.certificate",

   * bodies may only be used with HTTP/2. Calls to HTTP/1 servers will fail before the HTTP request
   * is transmitted. If you cannot ensure that your client and server both support HTTP/2, do not
   * use this feature.
   *
   * ### Duplex APIs
   *
   * With regular request bodies it is not legal to write bytes to the sink passed to

{* ../../docs_src/body_nested_models/tutorial007_py310.py hl[7,12,18,21,25] *}

/// info

Notice how `Offer` has a list of `Item`s, which in turn have an optional list of `Image`s

///

## Bodies of pure lists { #bodies-of-pure-lists }

If the top level value of the JSON body you expect is a JSON `array` (a Python `list`), you can declare the type in the parameter of the function, the same as in Pydantic models:

```Python

///

## Use cases { #use-cases }

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. [`msgpack`](https://msgpack.org/index.html)).
* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings { #handling-custom-request-body-encodings }