Path-параметр всегда является обязательным, поскольку он составляет часть пути.

Поэтому следует объявить его с помощью `...`, чтобы обозначить, что этот параметр обязательный.

Тем не менее, даже если вы объявите его как `None` или установите для него значение по умолчанию, это ни на что не повлияет и параметр останется обязательным.

///

## Задайте нужный вам порядок параметров

/// tip | "Подсказка"

可在一个*路径操作*中声明多个 `File` 和 `Form` 参数，但不能同时声明要接收 JSON 的 `Body` 字段。因为此时请求体的编码是 `multipart/form-data`，不是 `application/json`。

这不是 **FastAPI** 的问题，而是 HTTP 协议的规定。

///

## 可选文件上传

您可以通过使用标准类型注解并将 None 作为默认值的方式将一个文件参数设为可选:

//// tab | Python 3.9+

```Python hl_lines="7  14"
{!> ../../docs_src/request_files/tutorial001_02_py310.py!}
```

////

//// tab | Python 3.8+

	// Total Size for objects that have not yet been replicated
	ReplicationPendingSizeV1 uint64 `json:"objectsPendingReplicationTotalSize"`
	// Total size for objects that have witness one or more failures and will be retried
	ReplicationFailedSizeV1 uint64 `json:"objectsFailedReplicationTotalSize"`
	// Total size for objects that have been replicated to destination

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

<!---
 Licensed to the Apache Software Foundation (ASF) under one or more
 contributor license agreements.  See the NOTICE file distributed with
 this work for additional information regarding copyright ownership.
 The ASF licenses this file to You under the Apache License, Version 2.0
 (the "License"); you may not use this file except in compliance with
 the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

<?xml version="1.0" encoding="UTF-8"?>
<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

package com.google.common.hash;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.concurrent.atomic.AtomicLong;

/**
 * One or more variables that together maintain an initially zero {@code long} sum. When updates
 * (method {@link #add}) are contended across threads, the set of variables may grow dynamically to

    // the resource is visible to the system class loader.
    assertThrows(IllegalArgumentException.class, () -> Resources.getResource(tempFile.getName()));

    // Now set the context loader to one that should find the resource.
    URL baseUrl = tempFile.getParentFile().toURI().toURL();
    URLClassLoader loader = new URLClassLoader(new URL[] {baseUrl});

package com.google.common.hash;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.concurrent.atomic.AtomicLong;

/**
 * One or more variables that together maintain an initially zero {@code long} sum. When updates
 * (method {@link #add}) are contended across threads, the set of variables may grow dynamically to

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A sorted set which forwards all its method calls to another sorted set. Subclasses should
 * override one or more methods to modify the behavior of the backing sorted set as desired per the
 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *