FastAPI includes an extremely easy to use, but extremely powerful <abbr title='also known as "components", "resources", "services", "providers"'><strong>Dependency Injection</strong></abbr> system.

* Even dependencies can have dependencies, creating a hierarchy or **"graph" of dependencies**.
* All **automatically handled** by the framework.

app = FastAPI()


@dataclass
class Item:
    name: str
    price: Optional[float] = None
    owner_ids: Optional[list[int]] = None


@app.get("/items/invalid", response_model=Item)
def get_invalid():
    return {"name": "invalid", "price": "foo"}


@app.get("/items/innerinvalid", response_model=Item)
def get_innerinvalid():

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}

									<c:forEach var="item" varStatus="s" items="${popularWords}">
										<c:if test="${s.index < 3}">
											<la:link
												href="/search?q=${f:u(item)}${fe:facetQuery()}${fe:geoQuery()}">${f:h(item)}</la:link>
										</c:if>
										<c:if test="${3 <= s.index}">
											<la:link styleClass="d-none d-sm-inline-block"

                            "type": "array",
                        },
                    },
                    "title": "HTTPValidationError",
                    "type": "object",
                },
                "Item": {
                    "properties": {
                        "name": {
                            "title": "Name",
                            "type": "string",
                        },

                    + "You have the following options to resolve this:" + System.lineSeparator()
                    + "  1. Preserve the model version by setting 'preserve.model.version=true' to generate a consumer POM with <modelVersion>4.2.0</modelVersion>, which supports mixins"
                    + System.lineSeparator()

    }

    /**
     * Retrieves a specific Kuromoji dictionary item by ID.
     *
     * @param dictId the dictionary ID
     * @param id the ID of the Kuromoji item to retrieve
     * @return JSON response containing the Kuromoji dictionary item
     */
    // GET /api/admin/dict/kuromoji/setting/{dictId}/{id}
    @Execute

        final int start = dstIndex;

        if (this.blob != null) {
            System.arraycopy(this.blob, 0, dst, dstIndex, this.blob.length);
            dstIndex += this.blob.length;
        } else {
            System.arraycopy(this.lmHash, 0, dst, dstIndex, this.lmHash.length);
            dstIndex += this.lmHash.length;
            System.arraycopy(this.ntHash, 0, dst, dstIndex, this.ntHash.length);

    await websocket.accept()
    for item in session:
        await websocket.send_text(f"{item}")


@app.websocket("/ws-broken")
async def websocket_endpoint_broken(websocket: WebSocket, session: BrokenSessionDep):
    await websocket.accept()
    for item in session:
        await websocket.send_text(f"{item}")  # pragma no cover


client = TestClient(app)

        if (reportPlugins != null) {
            // new-style report configuration already present: warn since this new style has been deprecated
            // in favor of classical reporting section MSITE-647 / MSITE-684
            problems.add(new ModelProblemCollectorRequest(Severity.WARNING, Version.BASE)
                    .setMessage("Reporting configuration should be done in <reporting> section, "