stanConnection, _ = stan.Connect("test-cluster", "test-client", stan.NatsURL("nats://yourusername:yoursecret@0.0.0.0:4222"), stan.SetConnectionLostHandler(func(c stan.Conn, _ error) {
  go func() {
   for {
    // Reconnect if the connection is lost.
    if stanConnection == nil || stanConnection.NatsConn() == nil ||  !stanConnection.NatsConn().IsConnected() {

./mc cp ./lrgfile minio1/newbucket

sleep 5
./mc stat --no-list minio2/newbucket
if [ $? -ne 0 ]; then
	echo "expecting bucket to be present. exiting.."
	exit_1
fi

./mc stat --no-list minio3/newbucket
if [ $? -ne 0 ]; then
	echo "expecting bucket to be present. exiting.."
	exit_1
fi

err_minio2=$(./mc stat --no-list minio2/newbucket/xxx --json | jq -r .error.cause.message)

Joe Tsai <******@****.***> 1472512232 -0700

```

由于我们必须用 `Query(default=None)` 替换默认值 `None`，`Query` 的第一个参数同样也是用于定义默认值。

所以：

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

...使得参数可选，等同于：

```Python
q: str = None
```

但是 `Query` 显式地将其声明为查询参数。

然后，我们可以将更多的参数传递给 `Query`。在本例中，适用于字符串的 `max_length` 参数：

```Python
q: Union[str, None] = Query(default=None, max_length=50)
```

将会校验数据，在数据无效时展示清晰的错误信息，并在 OpenAPI 模式的*路径操作*中记录该参​​数。

	}
	if unMarshalXLMeta.Stat.Size != jsoniterXLMeta.Stat.Size {
		t.Errorf("Expected the stat size to be %v, but got %v.", unMarshalXLMeta.Stat.Size, jsoniterXLMeta.Stat.Size)
	}
	if !unMarshalXLMeta.Stat.ModTime.Equal(jsoniterXLMeta.Stat.ModTime) {
		t.Errorf("Expected the modTime to be \"%v\", but got \"%v\".", unMarshalXLMeta.Stat.ModTime, jsoniterXLMeta.Stat.ModTime)
	}

Joe Tsai <******@****.***> 1472512232 -0700

Joe Tsai <******@****.***> 1503105518 -0700

```

////

The query parameter `q` is of type `Union[str, None]` (or `str | None` in Python 3.10), that means that it's of type `str` but could also be `None`, and indeed, the default value is `None`, so FastAPI will know it's not required.

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

The `Union` in `Union[str, None]` will allow your editor to give you better support and detect errors.

Joe Tsai <******@****.***> 1503528984 -0700

```

////

Der Query-Parameter `q` hat den Typ `Union[str, None]` (oder `str | None` in Python 3.10), was bedeutet, er ist entweder ein `str` oder `None`. Der Defaultwert ist `None`, also weiß FastAPI, der Parameter ist nicht erforderlich.

/// note | "Hinweis"

FastAPI weiß nur dank des definierten Defaultwertes `=None`, dass der Wert von `q` nicht erforderlich ist