## Install dependencies { #install-dependencies }

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `jinja2`:

<div class="termy">

```console
$ pip install jinja2

---> 100%
```

</div>

## Using `Jinja2Templates` { #using-jinja2templates }

* Import `Jinja2Templates`.

### 查看它

在瀏覽器中打開 <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

你將看到如下的 JSON 回應：

```JSON
{"message": "Hello World"}
```

### 互動式 API 文件

現在，前往 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

你將看到自動的互動式 API 文件（由 <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank">Swagger UI</a> 提供）：

`int`가 아닌 `float`을 전달하는 경우에도 동일한 오류가 나타납니다: <a href="http://127.0.0.1:8000/items/4.2" class="external-link" target="_blank">http://127.0.0.1:8000/items/4.2</a>

/// check | 확인

즉, 파이썬 타입 선언을 하면 **FastAPI**는 데이터 검증을 합니다.

오류에는 정확히 어느 지점에서 검증을 통과하지 못했는지 명시됩니다.

이는 API와 상호 작용하는 코드를 개발하고 디버깅하는 데 매우 유용합니다.

///

## 문서화

import org.apache.maven.execution.MavenExecutionRequest;
import org.apache.maven.execution.MavenSession;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertNull;

/**
 */
class DefaultLegacySupportTest {
    final CountDownLatch latch = new CountDownLatch(1);
    final DefaultLegacySupport defaultLegacySupport = new DefaultLegacySupport();

    @Test
    void testSetSession() throws Exception {

 * and reports them as TeamCity build problems.
 */
registerBuildScanInfoCollectingService(CollectFailedTaskPathsBuildService::class.java, ::shouldBeReportedAsTeamCityBuildProblem) { gradleRootProject, failedTasksInBuildLogic, failedTasksInMainBuild ->
    gradleRootProject.extensions.findByType<BuildScanConfiguration>()?.run {
        buildScanPublished {

            entry.select("ul li")
                .map { it.text() }

        )
    }


internal
data class ReportMessage(
    val message: String,
    val details: List<String>
)


internal
data class RichReport(
    val errors: List<ReportMessage>,
    val warnings: List<ReportMessage>,
    val information: List<ReportMessage>,
    val accepted: List<ReportMessage>

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


@app.post("/items/")
async def create_item(item: Item) -> Item:
    return item


@app.get("/items/")
async def read_items() -> list[Item]:

from pydantic import BaseModel, HttpUrl

app = FastAPI()


class Image(BaseModel):
    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()
    images: Union[list[Image], None] = None


class Offer(BaseModel):
    name: str
    description: Union[str, None] = None

そして、DockerにはDockerイメージ（コンテナ）を共有する<a href="https://hub.docker.com/" class="external-link" target="_blank">Docker Hub</a>というものがあります。

Docker Hubは 多くのツールや環境、データベース、アプリケーションに対応している予め作成された**公式のコンテナ・イメージ**をパブリックに提供しています。

例えば、公式イメージの1つに<a href="https://hub.docker.com/_/python" class="external-link" target="_blank">Python Image</a>があります。

その他にも、データベースなどさまざまなイメージがあります：

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>

import static org.junit.jupiter.api.Assertions.assertEquals;

/**
 * Verifies that subclasses from generated model classes are possible.
 */
class ExtendedPluginDescriptorTest {

    /**
     * A subclass of the generated class {@link PluginDescriptor} that adds an additional field.
     */
    static class ExtendedPluginDescriptor extends PluginDescriptor {

        private final String additionalField;