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.

///

				failOnErr(err)
				_, err = hash.Write(data)
				failOnErr(err)
				got[conf] = map[ErasureAlgo]uint64{algo: hash.Sum64()}
			}

			if a, b := want[conf], got[conf]; !reflect.DeepEqual(a, b) {
				fmt.Fprintf(os.Stderr, "%v: error on self-test [d:%d,p:%d]: want %#v, got %#v\n", algo, conf[0], conf[1], a, b)
				ok = false
				continue
			}
			// Delete first shard and reconstruct...
			first := encoded[0]

## Do not Separate Schemas { #do-not-separate-schemas }

Now, there are some cases where you might want to have the **same schema for input and output**.

Probably the main use case for this is if you already have some autogenerated client code/SDKs and you don't want to update all the autogenerated client code/SDKs yet, you probably will want to do it at some point, but maybe not right now.

		Ciphertext: key.Ciphertext,
	})
	if err != nil {
		t.Fatalf("Failed to decrypt key: %v", err)
	}
	if !bytes.Equal(key.Plaintext, plaintext) {
		t.Fatalf("Decrypted key does not match generated one: got %x - want %x", key.Plaintext, plaintext)
	}
}

func TestDecryptKey(t *testing.T) {
	KMS, err := ParseSecretKey("my-key:eEm+JI9/q4JhH8QwKvf3LKo4DEBl6QbfvAl1CAbMIv8=")
	if err != nil {

		version string
		format  string
		want    bool
	}{
		{1, "123", "fs", false},
		{2, "123", xlMetaFormat, false},
		{3, xlMetaVersion100, "test", false},
		{4, xlMetaVersion101, "hello", false},
		{5, xlMetaVersion100, xlMetaFormat, true},
		{6, xlMetaVersion101, xlMetaFormat, true},
	}
	for _, tt := range tests {
		if got := isXLMetaFormatValid(tt.version, tt.format); got != tt.want {

This is the driest thing I know.  Silence all round, if you please!
"William the Conqueror, whose cause was favoured by the pope, was
soon submitted to by the English, who wanted leaders, and had been
of late much accustomed to usurpation and conquest.  Edwin and
Morcar, the earls of Mercia and Northumbria--"'

  `Ugh!' said the Lory, with a shiver.

# Development - Contributing

First, you might want to see the basic ways to [help FastAPI and get help](help-fastapi.md).

## Developing

If you already cloned the [fastapi repository](https://github.com/fastapi/fastapi) and you want to deep dive in the code, here are some guidelines to set up your environment.

### Install requirements

Create a virtual environment and install the required packages with [`uv`](https://github.com/astral-sh/uv):

{* ../../docs_src/bigger_applications/app_an_py310/internal/admin.py hl[3] title["app/internal/admin.py"] *}

But we still want to set a custom `prefix` when including the `APIRouter` so that all its *path operations* start with `/admin`, we want to secure it with the `dependencies` we already have for this project, and we want to include `tags` and `responses`.

     * <p>
     * This method is called by Maven during initialization to collect all custom enum values
     * that should be registered. The returned collection should contain all the enum values
     * that this provider wants to contribute.
     * <p>
     * The values returned by this method should be created using the appropriate factory methods
     * for the specific enum type, such as {@code language()}, {@code projectScope()}, or

This is probably not as important or necessary if you use `Annotated`.

///

Let's say that you want to declare the query parameter `q` as a required `str`.

And you don't need to declare anything else for that parameter, so you don't really need to use `Query`.

But you still need to use `Path` for the `item_id` path parameter. And you don't want to use `Annotated` for some reason.