# Custom Request and APIRoute class

In some cases, you may want to override the logic used by the `Request` and `APIRoute` classes.

In particular, this may be a good alternative to logic in a middleware.

For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

If you are just starting with **FastAPI** you might want to skip this section.

///

### When Things are Difficult

When things are great, everything is easier, so that doesn't need much instructions. But when things are difficult, here are some guidelines.

me see:  that would be four thousand miles down, I think--' (for,
you see, Alice had learnt several things of this sort in her
lessons in the schoolroom, and though this was not a VERY good
opportunity for showing off her knowledge, as there was no one to
listen to her, still it was good practice to say it over) `--yes,
that's about the right distance--but then I wonder what Latitude
or Longitude I've got to?'  (Alice had no idea what Latitude was,

  - Fixing or improving documentation.
  - Improvements to Maven configuration.

Guidelines for any code contributions:

  1. Any significant changes should be accompanied by tests. The project already
     has good test coverage, so look at some existing tests if you're unsure
     how to go about it.
  2. All contributions must be licensed Apache 2.0 and all files must have a

		},
		// duplicate '$bucket' reject
		{

          URISyntaxException.class);

  @Param Validator validator;
  @Param Result result;
  @Param ExceptionType exceptionType;
  /**
   * The number of other exception types in the cache of known-good exceptions and the number of
   * other {@code ClassValue} entries for the exception type to be tested. This lets us evaluate
   * whether our solution scales to use with multiple exception types and to whether it is affected

        MavenProperties p2 = new MavenProperties();
        p2.put(
                "fruits",
                List.of("#", "# List of good fruits", "#"),
                List.of("                           apple, banana, pear"));
        p2.put("trees", "fir, oak, maple");
        p1.update(p2);

        assertEquals(2, (Object) p1.size());

 * code point. An additional safe range is provided that determines whether code points without
 * specific replacements are to be considered safe and left unescaped or should be escaped in a
 * general way.
 *
 * <p>A good example of usage of this class is for HTML escaping where the replacement array
 * contains information about the named HTML entities such as {@code &amp;} and {@code &quot;} while

   * href="http://en.wikipedia.org/wiki/UTF-16">UTF-16</a> before calling this method.
   *
   * <p><b>Note:</b> When implementing an escaper it is a good idea to override this method for
   * efficiency by inlining the implementation of {@link #nextEscapeIndex(CharSequence, int, int)}
   * directly. Doing this for {@link com.google.common.net.PercentEscaper} more than doubled the

In many cases it's not very obvious how environment variables would be useful and applicable right away. But they keep showing up in many different scenarios when you are developing, so it's good to know about them.