Então:

```Python
q: Union[str, None] = Query(default=None)
```

...Torna o parâmetro opcional, da mesma maneira que:

```Python
q: Union[str, None] = None
```

Mas o declara explicitamente como um parâmetro de consulta.

/// info | Informação

   * Tests equality of {@link Hashing#goodFastHash} instances. This test must be separate from
   * {@link #testSeededHashFunctionEquals} because the parameter to {@code goodFastHash} is a size,
   * not a seed, and because that size is rounded up. Thus, {@code goodFastHash} instances with
   * different parameters can be equal. That fact is a problem for {@code
   * testSeededHashFunctionEquals}.
   */

    * Wanneer dat niet het geval is, krijgt de cliënt een nuttige, duidelijke foutmelding.
* Controleren of er een optionele query parameter is met de naam `q` (zoals in `http://127.0.0.1:8000/items/foo?q=somequery`) voor `GET` verzoeken.
    * Aangezien de `q` parameter werd gedeclareerd met `= None`, is deze optioneel.
    * Zonder de `None` declaratie zou deze verplicht zijn (net als bij de body in het geval met `PUT`).

    }

    /**
     * Stores a parameter value with the specified key.
     *
     * @param key the parameter key, must not be null
     * @param value the parameter value, may be null
     */
    public void put(final String key, final Object value) {
        params.put(key, value);
    }

    /**
     * Retrieves a parameter value by key.
     *
     * @param key the parameter key to look up

    /**
     * Returns {@literal true} if the parameter type of the constructor is parameterized.
     *
     * @param index
     *            The index of the parameter
     * @return {@literal true} if the parameter type is parameterized
     */
    boolean isParameterized(int index);

    /**
     * Returns an array of {@link ParameterizedClassDesc} representing the parameter types of the method.
     *

    }

    /**
     * Sets the parameter key.
     * @param parameterKey The parameter key.
     */
    public void setParameterKey(final String parameterKey) {
        this.parameterKey = parameterKey;
    }

    /**
     * Sets whether the parameter value is encrypted.
     * @param encryptedParameterValue Whether the parameter value is encrypted.
     */

Dan dokumentasi tetap berfungsi walaupun tidak menambahkan keterangan bahwa parameter harus berisi *path*.

### Konverter path

Melalui Starlette anda bisa mendeklarasikan *parameter path* berisi *path* dengan URL seperti:

```
/files/{file_path:path}
```

Dikondisi ini nama parameter adalah `file_path` dan bagian terakhir `:path` menginformasikan parameter harus sesuai dengan setiap *path*.

Sehingga anda bisa menggunakan:

     * Set the value of hostname, used in parameter comment. <br>
     * Even if empty string, treated as empty plainly. So "IF pmb != null" is false if empty.
     * @param hostname The parameter value of hostname. (NotNull)
     */
    public void setHostname(String hostname) {
        registerVariable("hostname", hostname);
    }

    /**
     * Set the value of jobname, used in parameter comment. <br>

{* ../../docs_src/using_request_directly/tutorial001.py hl[1,7:8] *}

By declaring a *path operation function* parameter with the type being the `Request` **FastAPI** will know to pass the `Request` in that parameter.

/// tip

Note that in this case, we are declaring a path parameter beside the request parameter.

So, the path parameter will be extracted, validated, converted to the specified type and annotated with OpenAPI.

## Requestbody- + Pfad- + Query-Parameter

Sie können auch zur gleichen Zeit **Body-**, **Pfad-** und **Query-Parameter** deklarieren.

**FastAPI** wird jeden Parameter korrekt erkennen und die Daten vom richtigen Ort holen.

{* ../../docs_src/body/tutorial004_py310.py hl[16] *}

Die Funktionsparameter werden wie folgt erkannt: