"termsOfService": "http://example.com/terms/",
            "contact": {
                "name": "Deadpoolio the Amazing",
                "url": "http://x-force.example.com/contact/",
                "email": "dp@x-force.example.com",
            },
            "license": {
                "name": "Apache 2.0",
                "identifier": "MIT",

If you need to enforce it, use `OAuth2PasswordRequestFormStrict` instead of `OAuth2PasswordRequestForm`.

///

* An optional `client_id` (we don't need it for our example).
* An optional `client_secret` (we don't need it for our example).

/// info

The `OAuth2PasswordRequestForm` is not a special class for **FastAPI** as is `OAuth2PasswordBearer`.

# Classes as Dependencies { #classes-as-dependencies }

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example { #a-dict-from-the-previous-example }

In the previous example, we were returning a `dict` from our dependency ("dependable"):

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

**FastAPI** will keep the additional information from `responses`, and combine it with the JSON Schema from your model.

For example, you can declare a response with a status code `404` that uses a Pydantic model and has a custom `description`.

And a response with a status code `200` that uses your `response_model`, but includes a custom `example`:

{* ../../docs_src/additional_responses/tutorial003_py39.py hl[20:31] *}

Puedes añadir código que se ejecute con la `request`, antes de que cualquier *path operation* la reciba.

Y también después de que se genere la `response`, antes de devolverla.

Por ejemplo, podrías añadir un custom header `X-Process-Time` que contenga el tiempo en segundos que tomó procesar la request y generar una response:

{* ../../docs_src/middleware/tutorial001_py39.py hl[10,12:13] *}

/// tip | Consejo

async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            openapi_examples={
                "normal": {
                    "summary": "A normal example",
                    "description": "A **normal** item works correctly.",
                    "value": {
                        "name": "Foo",
                        "description": "A very nice Item",

@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item = Body(
        openapi_examples={
            "normal": {
                "summary": "A normal example",
                "description": "A **normal** item works correctly.",
                "value": {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,

objectClass: inetOrgPerson
cn: Alice Smith
sn: Smith
uid: alice1
mail: alice@example.io
userPassword: {SSHA}Yeh2/IV/q/HjG2yzN3YdE9CAF3EJFCLu

dn: uid=bobfisher,ou=people,ou=hwengg,dc=min,dc=io
objectClass: inetOrgPerson
cn: Robert Fisher
sn: Fisher
uid: bobfisher
mail: bob@example.io
userPassword: {SSHA}LktfbhK5oXSdDWCNzauJ9JA+Poxinl3y

dn: uid=cody3,ou=people,ou=hwengg,dc=min,dc=io

    `HTTPDigest` in a dependency.

    The HTTP authorization header value is split by the first space.

    The first part is the `scheme`, the second part is the `credentials`.

    For example, in an HTTP Bearer token scheme, the client will send a header
    like:

    ```
    Authorization: Bearer deadbeef12346
    ```

    In this case:

    * `scheme` will have the value `"Bearer"`

For example, an 16-server distributed setup with 200 drives per node would continue serving files, up to 4 servers can be offline in default configuration i.e around 800 drives down MinIO would continue to read and write objects.