Takes some data and returns an `application/json` encoded response.

This is the default response used in **FastAPI**, as you read above.

### `ORJSONResponse` { #orjsonresponse }

A fast alternative JSON response using <a href="https://github.com/ijl/orjson" class="external-link" target="_blank">`orjson`</a>, as you read above.

/// info

This requires installing `orjson` for example with `pip install orjson`.

///

    }
  }

  /**
   * Returns an unmodifiable view of the specified table. This method allows modules to provide
   * users with "read-only" access to internal tables. Query operations on the returned table "read
   * through" to the specified table, and attempts to modify the returned table, whether direct or
   * via its collection views, result in an {@code UnsupportedOperationException}.
   *

# Custom Response Classes - File, HTML, Redirect, Streaming, etc.

There are several custom response classes you can use to create an instance and return them directly from your *path operations*.

Read more about it in the [FastAPI docs for Custom Response - HTML, Stream, File, others](https://fastapi.tiangolo.com/advanced/custom-response/).

You can import them directly from `fastapi.responses`:

```python
from fastapi.responses import (
    FileResponse,

When you need `lifespan` to run in your tests, you can use the `TestClient` with a `with` statement:

{* ../../docs_src/app_testing/tutorial004.py hl[9:15,18,27:28,30:32,41:43] *}


You can read more details about the ["Running lifespan in tests in the official Starlette documentation site."](https://www.starlette.io/lifespan/#running-lifespan-in-tests)

        buffer[7] = 0x00;
        // lastNameOffset (2 bytes)
        buffer[8] = 0x10;
        buffer[9] = 0x00;

        int result = response.readParametersWireFormat(buffer, 0, 10);

        // Should read 10 bytes
        assertEquals(10, result);
        // Check the values were parsed correctly
        assertEquals(1, response.getSid());
        assertEquals(5, response.getNumEntries());

## Other middlewares { #other-middlewares }

You can later read more about other middlewares in the [Advanced User Guide: Advanced Middleware](../advanced/middleware.md){.internal-link target=_blank}.

      while (true) {
        try {
          Thread.sleep(everyMillis);
        } catch (InterruptedException e) {
          // ok. just stop sleeping.
        }
        if (shouldStop) {
          break;
        }
        interruptee.interrupt();
      }
    }

    void stopInterrupting() {
      shouldStop = true;
    }
  }

                            handlerClass = ClassLoader.getSystemClassLoader().loadClass(className);
                        }
                        handler = (URLStreamHandler) handlerClass.newInstance();
                        break;
                    } catch (final Exception ex) {
                        log.debug("Failed to initialize handler " + className, ex);
                    }
                }
            }

 - **CacheHit**
 - CallEnd
 
### Cache Miss

Under a cache miss the normal request events are seen but an additional event shows the presence of the cache.
Cache Miss will be typical if the item has not been read from the network, is uncacheable, or is past it's 
lifetime based on Response cache headers.

 - CallStart 
 - **CacheMiss**
 - ProxySelectStart
 - ... Standard Events ...
 - CallEnd
        

# Templating - `Jinja2Templates`

You can use the `Jinja2Templates` class to render Jinja templates.

Read more about it in the [FastAPI docs for Templates](https://fastapi.tiangolo.com/advanced/templates/).

You can import it directly from `fastapi.templating`:

```python
from fastapi.templating import Jinja2Templates
```