If you want to return additional status codes apart from the main one, you can do that by returning a `Response` directly, like a `JSONResponse`, and set the additional status code directly.

For example, let's say that you want to have a *path operation* that allows to update items, and returns HTTP status codes of 200 "OK" when successful.

But in some cases you need to return a different status code than the default.

## Use case { #use-case }

For example, imagine that you want to return an HTTP status code of "OK" `200` by default.

But if the data didn't exist, you want to create it, and return an HTTP status code of "CREATED" `201`.

But you still want to be able to filter and convert the data you return with a `response_model`.

For those cases, you can use a `Response` parameter.

This means that you can send only the data that you want to update, leaving the rest intact.

/// note

`PATCH` is less commonly used and known than `PUT`.

And many teams use only `PUT`, even for partial updates.

You are **free** to use them however you want, **FastAPI** doesn't impose any restrictions.

But this guide shows you, more or less, how they are intended to be used.

///

## Previous Steps Before Starting { #previous-steps-before-starting }

There are many cases where you want to perform some steps **before starting** your application.

For example, you might want to run **database migrations**.

But in most cases, you will want to perform these steps only **once**.

So, you will want to have a **single process** to perform those **previous steps**, before starting the application.

type Checker struct {
	c io.Closer
	r io.Reader
	h hash.Hash

	want []byte
}

// NewChecker ensures that content with the specified length is read from rc.
// Calling Close on this will close upstream.
func NewChecker(rc io.ReadCloser, h hash.Hash, wantSum []byte, length int64) *Checker {
	return &Checker{c: rc, r: ioutil.HardLimitReader(rc, length), h: h, want: wantSum}
}

// Read satisfies io.Reader

						Mode:  RetCompliance,
						Years: yearsPtr,
					},
				},
			},
			want: "Enabled: true, Mode: COMPLIANCE, Years: 2",
		},
		{
			name: "disabled case",
			c: Config{
				ObjectLockEnabled: "Disabled",
			},
			want: "Enabled: false",
		},
		{
			name: "empty case",
			c:    Config{},
			want: "Enabled: false",
		},
	}
	for _, tt := range tests {
		got := tt.c.String()

But you are not restricted to using some specific data model, class or type.

Do you want to have an `id` and `email` and not have any `username` in your model? Sure. You can use these same tools.

Do you want to just have a `str`? Or just a `dict`? Or a database class model instance directly? It all works the same way.

		t.Log("Roundtrip:", time.Since(start))
		if len(resp) != 0 {
			t.Errorf("want nil, got %q", string(resp))
		}
		if err != RemoteErr(testPayload) {
			t.Errorf("want error %v(%T), got %v(%T)", RemoteErr(testPayload), RemoteErr(testPayload), err, err)
		}
		t.Log("Roundtrip:", time.Since(start))
	})

	t.Run("localToRemoteHuge", func(t *testing.T) {

	},
}

func TestString(t *testing.T) {
	for i, test := range stringTests {
		s := test.ETag.String()
		if s != test.String {
			t.Fatalf("Test %d: got %s - want %s", i, s, test.String)
		}
	}
}

var equalTests = []struct {
	A     string
	B     string
	Equal bool
}{
	{A: "3b83ef96387f14655fc854ddc3c6bd57", B: "3b83ef96387f14655fc854ddc3c6bd57", Equal: true},   // 0

	}
	// mustRead reads from input and compares against provided slice.
	mustRead := func(b ...byte) error {
		for _, want := range b {
			got, err := cr.reader.ReadByte()
			if err == io.EOF {
				return io.ErrUnexpectedEOF
			}
			if got != want {
				if cr.debug {
					fmt.Printf("mustread: want: %q got: %q\n", string(want), string(got))
				}
				return errMalformedEncoding
			}
			if err != nil {
				return err
			}
		}