@pytest.mark.parametrize(
    ("path", "expected_json"),
    [
        (
            "/items/foo",
            {
                "item_id": "foo",
                "description": "This is an amazing item that has a long description",
            },
        ),
        (
            "/items/bar?q=somequery",
            {
                "item_id": "bar",
                "q": "somequery",

    return fake_db[item_id]


@app.post("/items/", response_model=Item)
async def create_item(item: Item, x_token: Annotated[str, Header()]):
    if x_token != fake_secret_token:
        raise HTTPException(status_code=400, detail="Invalid X-Token header")
    if item.id in fake_db:
        raise HTTPException(status_code=409, detail="Item already exists")
    fake_db[item.id] = item

from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


responses = {
    404: {"description": "Item not found"},
    302: {"description": "The item was moved"},
    403: {"description": "Not enough privileges"},
}


app = FastAPI()


@app.get(
    "/items/{item_id}",
    response_model=Item,
    responses={**responses, 200: {"content": {"image/png": {}}}},

        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/items/{item_id}": {
                "put": {
                    "summary": "Update Item",
                    "operationId": "update_item_items__item_id__put",
                    "parameters": [
                        {
                            "name": "item_id",
                            "in": "path",
                            "required": True,

    return client


@pytest.mark.parametrize(
    "url,data",
    [
        ("/items/foo", {"name": "Foo", "price": 50.2}),
        (
            "/items/bar",
            {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
        ),
        (
            "/items/baz",
            {
                "name": "Baz",
                "description": None,

from fastapi import FastAPI

app = FastAPI()

items = {}


@app.on_event("startup")
async def startup_event():
    items["foo"] = {"name": "Fighters"}
    items["bar"] = {"name": "Tenders"}


@app.get("/items/{item_id}")
async def read_items(item_id: str):

    [
        (
            "/users/123/items/foo",
            {
                "item_id": "foo",
                "owner_id": 123,
                "description": "This is an amazing item that has a long description",
            },
        ),
        (
            "/users/1/items/bar?q=somequery",
            {
                "item_id": "bar",
                "owner_id": 1,

        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/items/{item_id}": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Return the JSON item or an image.",
                            "content": {
                                "image/png": {},

        "paths": {
            "/items/{item_id}": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {
                                "application/json": {
                                    "schema": {"$ref": "#/components/schemas/Item"}
                                }

{* ../../docs_src/path_params/tutorial001_py39.py hl[6:7] *}

The value of the path parameter `item_id` will be passed to your function as the argument `item_id`.

So, if you run this example and go to <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>, you will see a response of:

```JSON
{"item_id":"foo"}
```

## Path parameters with types { #path-parameters-with-types }