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   "source": [
    "# FastAPI 子应用\n",
    "\n",
    "参考：[sub-applications](https://fastapi.tiangolo.com/zh/advanced/sub-applications/)\n",
    "\n",
    "如果你需要有两个独立的 FastAPI 应用程序，它们有自己独立的 OpenAPI 和自己的文档 UI，你可以分别拥有主应用程序和“挂载”的一个或多个子应用程序。\n",
    "\n",
    "## 挂载 FastAPI 应用程序\n",
    "\n",
    "“挂载”意味着在特定路径中添加完全“独立”的应用程序，然后处理该路径下的所有内容，并在该子应用程序中声明路径操作。\n",
    "\n",
    "### 顶层 FastAPI 应用程序\n",
    "\n",
    "首先，创建主要的顶层 FastAPI 应用程序及其路径操作："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "from fastapi import FastAPI\n",
    "\n",
    "app = FastAPI()\n",
    "\n",
    "\n",
    "@app.get(\"/app\")\n",
    "def read_main():\n",
    "    return {\"message\": \"Hello World from main app\"}"
   ]
  },
  {
   "attachments": {},
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 子应用\n",
    "\n",
    "然后，创建子应用程序及其路径操作。\n",
    "\n",
    "这里的子应用程序只是另一个标准的 FastAPI 应用程序，但它将被“挂载”："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "subapi = FastAPI()\n",
    "\n",
    "\n",
    "@subapi.get(\"/sub\")\n",
    "def read_sub():\n",
    "    return {\"message\": \"Hello World from sub API\"}"
   ]
  },
  {
   "attachments": {},
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 挂载子应用程序\n",
    "\n",
    "在顶层应用程序 `app` 中，挂载子应用程序 `subapi`。\n",
    "\n",
    "在这种情况下，它将被挂载在 `/subapi` 路径下："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "app.mount(\"/subapi\", subapi)"
   ]
  },
  {
   "attachments": {},
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 挂载其他 WSGI 组件\n",
    "\n",
    "可以使用 `WSGIMiddleware` 来包装你的 WSGI 应用，如：Flask，Django 等。\n",
    "\n",
    "使用中间件包装 WSGI 应用（例如 Flask），之后将其挂载到某一个路径下："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "from fastapi import FastAPI\n",
    "from fastapi.middleware.wsgi import WSGIMiddleware\n",
    "from flask import Flask, escape, request\n",
    "\n",
    "flask_app = Flask(__name__)\n",
    "\n",
    "\n",
    "@flask_app.route(\"/\")\n",
    "def flask_main():\n",
    "    name = request.args.get(\"name\", \"World\")\n",
    "    return f\"Hello, {escape(name)} from Flask!\"\n",
    "\n",
    "\n",
    "app = FastAPI()\n",
    "\n",
    "\n",
    "@app.get(\"/v2\")\n",
    "def read_main():\n",
    "    return {\"message\": \"Hello World\"}\n",
    "\n",
    "\n",
    "app.mount(\"/v1\", WSGIMiddleware(flask_app))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{note}\n",
    "现在，所有定义在 `/v1/` 路径下的请求将会被 Flask 应用处理。其余的请求则会被 FastAPI 处理。\n",
    "```"
   ]
  }
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