*
 * <p>There are three primary interfaces provided to represent graphs. In order of increasing
 * complexity they are: {@link Graph}, {@link ValueGraph}, and {@link Network}. You should generally
 * prefer the simplest interface that satisfies your use case. See the <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#choosing-the-right-graph-type">
 * "Choosing the right graph type"</a> section of the Guava User Guide for more details.

                            "title": "Name",
                            "examples": ["Foo"],
                        },
                        "description": {
                            "anyOf": [{"type": "string"}, {"type": "null"}],
                            "title": "Description",
                            "examples": ["A very nice Item"],
                        },
                        "price": {

  }

  public void testCopyOf_concurrentlyMutating() {
    List<String> sample = Lists.newArrayList("a", "b", "c");
    for (int delta : new int[] {-1, 0, 1}) {
      for (int i = 0; i < sample.size(); i++) {
        Collection<String> misleading = misleadingSizeCollection(delta);
        List<String> expected = sample.subList(0, i);
        misleading.addAll(expected);

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None

    class Config:
        schema_extra = {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]

import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Package up sample data for common collections benchmarking.
 *
 * @author Nicholaus Shupe
 */
@NullUnmarked
class CollectionBenchmarkSampleData {
  private final boolean isUserTypeFast;
  private final SpecialRandom random;

class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None

    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None

    class Config:
        schema_extra = {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]

    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ],

使用上面的任何方法，它在 `/docs` 中看起来都是这样的:

<img src="/img/tutorial/body-fields/image01.png">

## 技术细节

关于 `example` 和 `examples`...

JSON Schema在最新的一个版本中定义了一个字段 <a href="https://json-schema.org/draft/2019-09/json-schema-validation.html#rfc.section.9.5" class="external-link" target="_blank">`examples`</a> ，但是 OpenAPI 基于之前的一个旧版JSON Schema，并没有 `examples`.

    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                },
                {