def get_recursive():
    return {"name": "item", "sub_items": [{"name": "subitem", "sub_items": []}]}


@app.get("/items/recursive-submodel", response_model=RecursiveItemViaSubmodel)
def get_recursive_submodel():
    return {
        "name": "item",
        "sub_items1": [
            {
                "name": "subitem",
                "sub_items2": [
                    {

def get_recursive():
    return {"name": "item", "sub_items": [{"name": "subitem", "sub_items": []}]}


@app.get("/items/recursive-submodel", response_model=RecursiveItemViaSubmodel)
def get_recursive_submodel():
    return {
        "name": "item",
        "sub_items1": [
            {
                "name": "subitem",
                "sub_items2": [
                    {

from fastapi import FastAPI

app = FastAPI()


@app.get("/app")
def read_main():
    return {"message": "Hello World from main app"}


subapi = FastAPI()


@subapi.get("/sub")
def read_sub():
    return {"message": "Hello World from sub API"}

from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class SubModel(BaseModel):
    a: Optional[str] = "foo"


class Model(BaseModel):
    x: Optional[int] = None
    sub: SubModel


class ModelSubclass(Model):
    y: int
    z: int = 0
    w: Optional[int] = None


class ModelDefaults(BaseModel):
    w: Optional[str] = None
    x: Optional[str] = None

```Python hl_lines="3  6-8"
{!../../../docs_src/sub_applications/tutorial001.py!}
```

### زیر برنامه

سپس، زیر برنامه خود و path operations آن را ایجاد کنید.

این زیر برنامه فقط یکی دیگر از برنامه های استاندارد FastAPI است، اما این برنامه ای است که متصل می شود:

```Python hl_lines="11  14-16"
{!../../../docs_src/sub_applications/tutorial001.py!}
```

### اتصال زیر برنامه

It might be useful, for example, to return custom headers or cookies.

## Return a `Response`

In fact, you can return any `Response` or any sub-class of it.

!!! tip
    `JSONResponse` itself is a sub-class of `Response`.

And when you return a `Response`, **FastAPI** will pass it directly.

It won't do any data conversion with Pydantic models, it won't convert the contents to any type, etc.

Deshalb, um ID-Kollisionen zu vermeiden, könnten Sie beim Erstellen des JWT-Tokens für den Benutzer, dem Wert des `sub`-Schlüssels ein Präfix, z. B. `username:` voranstellen. In diesem Beispiel hätte der Wert von `sub` also auch `username:johndoe` sein können.

Der wesentliche Punkt ist, dass der `sub`-Schlüssel in der gesamten Anwendung eine eindeutige Kennung haben sollte, und er sollte ein String sein.

## Es testen

⚙️ 👫 💭, 🥙 💪 ⚙️ 🌌 🌖 🤓 😐.

📚 💼, 📚 👈 👨‍💼 💪 ✔️ 🎏 🆔, ➡️ 💬 `foo` (👩‍💻 `foo`, 🚘 `foo`, & 📰 🏤 `foo`).

, ❎ 🆔 💥, 🕐❔ 🏗 🥙 🤝 👩‍💻, 👆 💪 🔡 💲 `sub` 🔑, ✅ ⏮️ `username:`. , 👉 🖼, 💲 `sub` 💪 ✔️: `username:johndoe`.

⚠ 👜 ✔️ 🤯 👈 `sub` 🔑 🔜 ✔️ 😍 🆔 🤭 🎂 🈸, & ⚫️ 🔜 🎻.

## ✅ ⚫️

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

### Sub-dependencies

But we also pass a `list` of scopes, in this case with just one scope: `items` (it could have more).

And the dependency function `get_current_active_user` can also declare sub-dependencies, not only with `Depends` but also with `Security`. Declaring its own sub-dependency function (`get_current_user`), and more scope requirements.

In this case, it requires the scope `me` (it could require more than one scope).

!!! note