from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str

    class Config:
        extra = "forbid"


@app.post("/login/")
async def login(data: Annotated[FormData, Form()]):

        }
        if (elements.length > 1) {
          /*
           * When a test requests a multiset with duplicates, our plan of
           * "add an extra item 0 to A and an extra item 1 to B" really means
           * "add an extra item 0 to A and B," which isn't what we want.
           */
          if (!Objects.equal(elements[0], elements[1])) {
            multiset2.add(elements[1], 2);
          }

from typing import Annotated, Union

from fastapi import Cookie, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Cookies(BaseModel):
    class Config:
        extra = "forbid"

    session_id: str
    fatebook_tracker: Union[str, None] = None
    googall_tracker: Union[str, None] = None


@app.get("/items/")
async def read_items(cookies: Annotated[Cookies, Cookie()]):

                    CompactHashSet<String> set = CompactHashSet.create(asList(elements));
                    for (int i = 0; i < 100; i++) {
                      set.add("extra" + i);
                    }
                    for (int i = 0; i < 100; i++) {
                      set.remove("extra" + i);
                    }
                    set.trimToSize();
                    return set;
                  }
                })

from typing import Union

from fastapi import Cookie, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Cookies(BaseModel):
    class Config:
        extra = "forbid"

    session_id: str
    fatebook_tracker: Union[str, None] = None
    googall_tracker: Union[str, None] = None


@app.get("/items/")
async def read_items(cookies: Annotated[Cookies, Cookie()]):

It will perform the validation of the compound data, and will document it like that for the OpenAPI schema and automatic docs.

## Singular values in body

The same way there is a `Query` and `Path` to define extra data for query and path parameters, **FastAPI** provides an equivalent `Body`.

For example, extending the previous model, you could decide that you want to have another key `importance` in the same body, besides the `item` and `user`.

from typing import Annotated, Literal

from fastapi import FastAPI, Query
from pydantic import BaseModel, Field

app = FastAPI()


class FilterParams(BaseModel):
    model_config = {"extra": "forbid"}

    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")

    <div class="md-copyright__highlight">
        The FastAPI trademark is owned by <a href="https://tiangolo.com" target="_blank">@tiangolo</a> and is registered in the US and across other regions
    </div>
    {% if not config.extra.generator == false %}
    Made with
    <a href="https://squidfunk.github.io/mkdocs-material/" target="_blank" rel="noopener">
        Material for MkDocs
    </a>
    {% endif %}

from fastapi import FastAPI, Query
from pydantic import BaseModel, Field
from typing_extensions import Annotated, Literal

app = FastAPI()


class FilterParams(BaseModel):
    class Config:
        extra = "forbid"

    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: List[str] = []


@app.get("/items/")

                }
            },
            "/response_model-no_annotation-return_dict_with_extra_data": {
                "get": {
                    "summary": "Response Model No Annotation Return Dict With Extra Data",
                    "operationId": "response_model_no_annotation_return_dict_with_extra_data_response_model_no_annotation_return_dict_with_extra_data_get",
                    "responses": {
                        "200": {