Here are several pointers to other places in the docs, for general or frequent questions.

## Filter Data - Security { #filter-data-security }

To ensure that you don't return more data than you should, read the docs for [Tutorial - Response Model - Return Type](../tutorial/response-model.md){.internal-link target=_blank}.

## Documentation Tags - OpenAPI { #documentation-tags-openapi }

    price: float
    is_offer: bool = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}
```

        public int getIndex() {
            return offset;
        }

        @Override
        public NdrBuffer derive(int offset) {
            return this; // For simplicity, return self
        }

        // Note: getDeferred() method does not exist in NdrBuffer
        public NdrBuffer getDeferred() {
            return this; // For simplicity, return self
        }

        @Override

                this.fileId = fileId;
                this.setCount++;
            }

            public byte[] getFileId() {
                return fileId;
            }

            public int getSetCount() {
                return setCount;
            }
        }

        // When
        CustomRequestWithFileId customRequest = new CustomRequestWithFileId();

 *
 *  @version 2.3.77
 *  @website http://formvalidator.net/
 *  @author Victor Jonsson, http://victorjonsson.se
 *  @license MIT
 */

            activeLogger.addHandler(handler)
          }
        }
      }
    }

    fun getLogger(name: String): Logger {
      val logger = Logger.getLogger(name)
      activeLoggers.add(logger)
      return logger
    }
  }

                final InputSource is = new InputSource(ResourceUtil.getResourceAsStream("org/codelibs/core/xml/included.xml"));
                is.setSystemId("included.xml");
                return is;
            }

        });
        assertTrue(included);
    }

    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}
```

    * As connecting to an email server and sending an email tends to be "slow" (several seconds), you can return the response right away and send the email notification in the background.
* Processing data:
    * For example, let's say you receive a file that must go through a slow process, you can return a response of "Accepted" (HTTP 202) and process the file in the background.

## Using `BackgroundTasks` { #using-backgroundtasks }

# 🔗 ⏮️ 🌾

FastAPI 🐕‍🦺 🔗 👈 <abbr title='sometimes also called "exit", "cleanup", "teardown", "close", "context managers", ...'>➕ 🔁 ⏮️ 🏁</abbr>.

👉, ⚙️ `yield` ↩️ `return`, &amp; ✍ ➕ 🔁 ⏮️.

/// tip

⚒ 💭 ⚙️ `yield` 1️⃣ 👁 🕰.

///

/// note | 📡 ℹ

🙆 🔢 👈 ☑ ⚙️ ⏮️:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> ⚖️