## The normal **FastAPI** app

Let's first see how the normal API app would look like before adding the callback.

It will have a *path operation* that will receive an `Invoice` body, and a query parameter `callback_url` that will contain the URL for the callback.

* 和你 **<abbr title="集成开发环境，和代码编辑器类似">IDE</abbr>/<abbr title="一个检查代码错误的程序">linter</abbr>/brain** 适配:
    * 因为 pydantic 数据结构仅仅是你定义的类的实例；自动补全，linting，mypy 以及你的直觉应该可以和你验证的数据一起正常工作。
* 验证**复杂结构**:
    * 使用分层的 Pydantic 模型, Python `typing`的 `List` 和 `Dict` 等等。
    * 验证器使我们能够简单清楚的将复杂的数据模式定义、检查并记录为 JSON Schema。
    * 你可以拥有深度**嵌套的 JSON** 对象并对它们进行验证和注释。
* **可扩展**:
    * Pydantic 允许定义自定义数据类型或者你可以用验证器装饰器对被装饰的模型上的方法扩展验证。

    * ↩️ Pydantic 📊 📊 👐 🎓 👆 🔬; 🚘-🛠️, 🧽, ✍ & 👆 🤔 🔜 🌐 👷 ☑ ⏮️ 👆 ✔ 💽.
* ✔ **🏗 📊**:
    * ⚙️ 🔗 Pydantic 🏷, 🐍 `typing`'Ⓜ `List` & `Dict`, ♒️.
    *  & 💳 ✔ 🏗 💽 🔗 🎯 & 💪 🔬, ✅ & 📄 🎻 🔗.
    * 👆 💪 ✔️ 🙇 **🐦 🎻** 🎚 & ✔️ 👫 🌐 ✔ & ✍.
* **🏧**:

```

!!! note
    Notice that as we communicate with the database using `await`, the *path operation function* is declared with `async`.

### Notice the `response_model=List[Note]`

It uses `typing.List`.

That documents (and validates, serializes, filters) the output data, as a `list` of `Note`s.

## Create notes

Create the *path operation function* to create notes:

```Python hl_lines="61-65"

    "Topic :: Software Development :: Libraries :: Python Modules",
    "Topic :: Software Development :: Libraries",
    "Topic :: Software Development",
    "Typing :: Typed",
    "Development Status :: 4 - Beta",
    "Environment :: Web Environment",
    "Framework :: AsyncIO",
    "Framework :: FastAPI",
    "Framework :: Pydantic",
    "Framework :: Pydantic :: 1",

### Importe `List` do typing

Primeiramente, importe `List` do módulo `typing` que já vem por padrão no Python:

```Python hl_lines="1"
{!../../../docs_src/body_nested_models/tutorial002.py!}
```

### Declare a `List` com um parâmetro de tipo

Para declarar tipos que têm parâmetros de tipo(tipos internos), como `list`, `dict`, `tuple`:

* Importe os do modulo `typing`

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application

- **Security:**
Java serialization poses security risks, especially related to deserialization vulnerabilities.

- **Version Compatibility:**
With Java serialization, even minor changes to a class (like adding a field) can break compatibility.

- **Cross-Language Compatibility:**
Java serialization is inherently Java-centric and does not support cross-language scenarios well.

- **Type Safety:**

If you want to use your APIs' function names as `operationId`s, you can iterate over all of them and override each *path operation's* `operation_id` using their `APIRoute.name`.

You should do it after adding all your *path operations*.

```Python hl_lines="2  12-21  24"
{!../../../docs_src/path_operation_advanced_configuration/tutorial002.py!}
```

!!! tip

# Guava Testlib: Google Testing Libraries for Java

Guava testlib is a set of Java classes for more convenient
unit testing.

## Adding Guava Testlib to your build

Guava testlib's Maven group ID is `com.google.guava` and its artifact ID is `guava-testlib`.

To add a dependency on Guava testlib using Maven, use the following:

```xml
<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava-testlib</artifactId>