# Custom Request and APIRoute class { #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.

    @Test
    public void test_dataPersistedAfterCreateIndex() throws Exception {
        Suggester suggester = createSuggester();
        suggester.createIndexIfNothing();

        // Index some data
        String[][] readings = new String[1][];
        readings[0] = new String[] { "test" };

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Some of these solutions may also be open source or offer free tiers, so you can try them without a financial commitment. Other commercial SDK generators are available and can be found online. 🤓

# Global Dependencies { #global-dependencies }

For some types of applications you might want to add dependencies to the whole application.

Similar to the way you can [add `dependencies` to the *path operation decorators*](dependencies-in-path-operation-decorators.md), you can add them to the `FastAPI` application.

In that case, they will be applied to all the *path operations* in the application:

{* ../../docs_src/dependencies/tutorial012_an_py310.py hl[17] *}

# This file specifies the Linux OS versions on which we can't build and
# test Docker images for some reason. These values correspond to ID and
# VERSION_ID from /etc/os-release, and a matching value will cause the
# Docker tests to be skipped on that OS. If /etc/os-release doesn't exist
# (as is the case on centos-6, for example) then that OS will again be
# excluded.
debian-8
opensuse-leap-15.1
ol-7.7
sles-12.3 # older version used in Vagrant image
sles-12.5

    /**
     * The parser request this instance was created from.
     */
    @Nonnull
    ParserRequest parserRequest();

    /**
     * Flag representing parser processing result: if there were some fatal errors during
     * {@link Parser#parseInvocation(ParserRequest)} this method will return {@code true} and invoker should
     * handle this request as "early failure". In these cases, {@link #options()} usually is absent.

	// ARNPrefix prefix for "arn:aws:kms"
	ARNPrefix = "arn:aws:kms:"
)

// IsMultiPart returns true if the object metadata indicates
// that it was uploaded using some form of server-side-encryption
// and the S3 multipart API.
func IsMultiPart(metadata map[string]string) bool {
	if _, ok := metadata[MetaMultipart]; ok {
		return true
	}
	return false
}

                pw.println("---------- Validation Report -----------");
                pw.println("Some API names were found that, when client code is generated for these APIS,");
                pw.println("could conflict with the reserved words in some programming languages. It may");
                pw.println("still be possible to use these API names, but you will need to verify whether");

    assertThat(cache.asMap().computeIfPresent(key, (k, v) -> "2")).isEqualTo("2");
  }

  public void testUpdates() {
    cache.put(key, "1");
    // simultaneous update for same key, some null, some non-null
    doParallelCacheOp(
        count, n -> cache.asMap().compute(key, (k, v) -> n % 2 == 0 ? v + delimiter + n : null));
    assertThat(cache.size()).isAtMost(1);
  }

  public void testCompute() {

</div>

次のようなリクエストを送れます:

```json
{
    "description": "Some data",
    "data": "aGVsbG8="
}
```

/// tip | 豆知識

`aGVsbG8=` は `hello` の base64 エンコードです。

///

その後、Pydantic は base64 文字列をデコードし、モデルの `data` フィールドに元のバイト列を渡します。

次のようなレスポンスを受け取ります:

```json
{
  "description": "Some data",
  "content": "hello"
}
```