It will already be installed with FastAPI.

```Python hl_lines="3-4"
{!> ../../docs_src/query_params_str_validations/tutorial002_an.py!}
```

////

/// info

FastAPI added support for `Annotated` (and started recommending it) in version 0.95.0.

If you have an older version, you would get errors when trying to use `Annotated`.

# 更大的应用 - 多个文件

如果你正在开发一个应用程序或 Web API，很少会将所有的内容都放在一个文件中。

**FastAPI** 提供了一个方便的工具，可以在保持所有灵活性的同时构建你的应用程序。

/// info

如果你来自 Flask，那这将相当于 Flask 的 Blueprints。

///

## 一个文件结构示例

假设你的文件结构如下：

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   ├── dependencies.py
│   └── routers
│   │   ├── __init__.py
│   │   ├── items.py
│   │   └── users.py
│   └── internal
│       ├── __init__.py

```

### ✅ 🏧 🛠️ 🩺

🔜, 🏃 `uvicorn` ⏮️ 👑 📱, 🚥 👆 📁 `main.py`, ⚫️ 🔜:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

&amp; 📂 🩺 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

### 🏗 🗄 🔗

⤴️, ⚙️ 🎏 🚙 🔢 🏗 🗄 🔗, 🔘 `custom_openapi()` 🔢:

```Python hl_lines="2  15-20"
{!../../docs_src/extending_openapi/tutorial001.py!}
```

### 🔀 🗄 🔗

🔜 👆 💪 🚮 📄 ↔, ❎ 🛃 `x-logo` `info` "🎚" 🗄 🔗:

```Python hl_lines="21-23"
{!../../docs_src/extending_openapi/tutorial001.py!}
```

### 💾 🗄 🔗

👆 💪 ⚙️ 🏠 `.openapi_schema` "💾", 🏪 👆 🏗 🔗.

@needs_py39
def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/files/": {
                "post": {
                    "summary": "Create File",
                    "operationId": "create_file_files__post",

        super.document1_CallableSuperMethod();
    }

    // ===================================================================================
    //                                                                           User Info
    //                                                                           =========
    @Override
    protected OptionalThing<LoginManager> myLoginManager() {
        return OptionalThing.of(fessLoginAssist);
    }

                                    <%-- Message --%>
                                <div>
                                    <la:info id="msg" message="true">
                                        <div class="alert alert-info">${msg}</div>
                                    </la:info>
                                    <la:errors/>
                                </div>
                                <div class="form-group row">

                            <div class="card-body">
                                <div>
                                    <la:info id="msg" message="true">
                                        <div class="alert alert-info">${msg}</div>
                                    </la:info>
                                    <la:errors property="_global"/>
                                </div>
                                <div class="form-group row">

				<p class="login-box-msg">
					<la:message key="labels.login" />
				</p>
				<%-- Message --%>
				<div>
					<la:info id="msg" message="false">
						<div class="alert alert-info">${msg}</div>
					</la:info>
					<la:errors />
				</div>
				<la:form styleId="login" method="post">
					<div class="input-group mb-3">
						<c:set var="ph_username">

				<p class="login-box-msg">
					<la:message key="labels.login.newpassword" />
				</p>
				<%-- Message --%>
				<div>
					<la:info id="msg" message="false">
						<div class="alert alert-info">${msg}</div>
					</la:info>
					<la:errors />
				</div>
				<la:form styleId="newPassword" method="post">
					<div class="input-group mb-3">
						<c:set var="ph_new_password">