private int size;

  enum CollectionType {
    ARRAY_LIST(ArrayList::new),
    LINKED_LIST(LinkedList::new);

    final Supplier<Collection<Object>> supplier;

    private CollectionType(Supplier<Collection<Object>> supplier) {
      this.supplier = supplier;
    }
  }

  @Param private CollectionType source;

  enum Operation {
    FIND_FIRST {
      @Override

@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
@ElementTypesAreNonnullByDefault
final class ImmutableEnumMap<K extends Enum<K>, V> extends IteratorBasedImmutableMap<K, V> {
  static <K extends Enum<K>, V> ImmutableMap<K, V> asImmutable(EnumMap<K, V> map) {
    switch (map.size()) {
      case 0:
        return ImmutableMap.of();
      case 1:

      }
    };
  }

  enum QueueImpl implements CollectionsImplEnum {
    MinMaxPriorityQueueImpl {
      @Override
      public <E extends Comparable<E>> Queue<E> create(Collection<E> contents) {
        return MinMaxPriorityQueue.create(contents);
      }
    };
  }

  enum TableImpl {
    HashBasedTableImpl {
      @Override

 * limitations under the License.
 */

package common

enum class Arch(val suffix: String, val nameOnLinuxWindows: String, val nameOnMac: String) {
    AMD64("64bit", "amd64", "x86_64"),
    AARCH64("aarch64", "aarch64", "aarch64");

    fun asName() = name.lowercase().toCapitalized()
}

enum class Os(
    val agentRequirement: String,
    val androidHome: String,
    val jprofilerHome: String,

import types
from enum import Enum
from typing import Any, Callable, Dict, Set, Type, TypeVar, Union

from pydantic import BaseModel

DecoratedCallable = TypeVar("DecoratedCallable", bound=Callable[..., Any])
UnionType = getattr(types, "UnionType", Union)
ModelNameMap = Dict[Union[Type[BaseModel], Type[Enum]], str]

 * serialization of funnels. When possible, it is recommended that funnels be implemented as a
 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item
 * 3: "Enforce the singleton property with a private constructor or an enum type". For example:
 *
 * <pre>{@code
 * public enum PersonFunnel implements Funnel<Person> {
 *   INSTANCE;
 *   public void funnel(Person person, PrimitiveSink into) {

from enum import Enum

from fastapi import FastAPI


class ModelName(str, Enum):
    alexnet = "alexnet"
    resnet = "resnet"
    lenet = "lenet"


app = FastAPI()


@app.get("/models/{model_name}")
async def get_model(model_name: ModelName):
    if model_name is ModelName.alexnet:
        return {"model_name": model_name, "message": "Deep Learning FTW!"}

    if model_name.value == "lenet":

```

否则，`/users/{user_id}` 将匹配 `/users/me`，FastAPI 会**认为**正在接收值为 `"me"` 的 `user_id` 参数。

## 预设值

路径操作使用 Python 的 <abbr title="Enumeration">`Enum`</abbr> 类型接收预设的*路径参数*。

### 创建 `Enum` 类

导入 `Enum` 并创建继承自 `str` 和 `Enum` 的子类。

通过从 `str` 继承，API 文档就能把值的类型定义为**字符串**，并且能正确渲染。

然后，创建包含固定值的类属性，这些固定值是可用的有效值：

```Python hl_lines="1  6-9"
{!../../docs_src/path_params/tutorial005.py!}

import dataclasses
import datetime
from collections import defaultdict, deque
from decimal import Decimal
from enum import Enum
from ipaddress import (
    IPv4Address,
    IPv4Interface,
    IPv4Network,
    IPv6Address,
    IPv6Interface,
    IPv6Network,
)
from pathlib import Path, PurePath
from re import Pattern
from types import GeneratorType
from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union

### Создание класса `Enum`

Импортируйте `Enum` и создайте подкласс, который наследуется от `str` и `Enum`.

Мы наследуемся от `str`, чтобы документация API могла понять, что значения должны быть типа `string` и отображалась правильно.