后端的Heroku路由在部署中不起作用

Question

我用React，Node和Mongodb创建了一个简单的待办事项应用程序。该应用程序在开发服务器上运行时运行良好。但是，当我部署它时，似乎该应用程序无法访问todo API路由。任何帮助将不胜感激，我已经为此奋斗了两天，但无济于事。感谢您的阅读。

package.json：

  "name": "server",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "engines": {
    "node": "14.0.0",
    "npm": "6.14.5"
  },
  "proxy": "http://localhost:5000",
  "dependencies": {
    "body-parser": "^1.19.0",
    "concurrently": "^5.2.0",
    "cors": "^2.8.5",
    "express": "^4.17.1",
    "mongodb": "^3.5.9",
    "mongoose": "^5.9.21"
  },
  "devDependencies": {},
  "scripts": {
    "server": "nodemon index.js",
    "start": "node index.js",
    "client": "npm run start --prefix client",
    "sass": "npm run sass --prefix client",
    "dev": "concurrently \"npm run server\" \"npm run client\" ",
    "heroku-postbuild": "npm install --prefix client && npm run build --prefix client"
  },
  "author": "",
  "license": "ISC"
}

这是我的前端get呼叫示例：

    axios
      .get("/get/list")
      .then((response) => {
        response.data.map((list) => {
          this.setState({ lists: [...this.state.lists, list] });
          return this.state.lists;
        });
      })
      .catch((err) => console.log(err));
  }

我后端的index.js：

const express = require("express");
const bodyParser = require("body-parser");
const mongoose = require("mongoose");
const keys = require("./config/keys");
const cors = require("cors");
const app = express();
const List = require("./models/List");

app.use(cors());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(express.json());

mongoose.connect(keys.MONGO_URI);

if (process.env.NODE_ENV === "production") {
  // Express will serve up production assets
  // like our main.js file, or main.css file
  app.use(express.static("client/build"));

  const path = require("path");
  app.get("*", (req, res) => {
    res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));
  });
}

require("./routes/listRoutes")(app);

app.get("/test", (req, res) => {
  console.log("test proxy works");
  res.send("test proxy works");
});

const PORT = process.env.PORT || 5000;
app.listen(process.env.PORT || 5000);

和listRoutes文件：

const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const List = require("../models/List");

module.exports = (app) => {
  // gets ALL List from database
  app.get("/get/list", async (req, res) => {
    let lists = await List.find({}, (err) => {
      err ? console.log(err) : null;
    });
    console.log(lists);
    res.send(lists);
  });

  // Create a new List
  app.post("/new/list", (req, res) => {
    let newList = new List({
      title: req.body.title,
      lists: [
        {
          category: "house",
          importance: 4,
          body: "Fix the fire detector",
          notes: "for safety",
        },
      ],
      created: new Date().toUTCString(),
    });

    newList.save((err) => {
      err;
    });

    res.send(newList);
  });

  // add new list item to it's List
  app.post("/new/listItem/:id", (req, res) => {
    const { category, body, importance, notes } = req.body;
    // creates new list item to be updated in the database
    var listUpdate = {
      category,
      body,
      importance,
      notes,
    };

    console.log(listUpdate);
    // finds the selected list and updates the lists array with a new list object
    List.findOneAndUpdate(
      { _id: req.params.id },
      { $push: { lists: listUpdate } },
      function (error, success) {
        if (error) {
          console.log(error);
        } else {
          console.log(success);
        }
      }
    );
    res.send(listUpdate);
  });

  // Find and edit a list item inside of a list
  app.post("/update/listItem/:id", async (req, res) => {
    let id = req.params.id;

    const { category, body, importance, notes } = req.body;
    const listItemUpdate = {
      category,
      body,
      importance,

      notes,
    };

    // this will require placeholder values of the previous list item values to prevent them from being overwritten with nothing
    await List.updateOne(
      // finds a database entry that matches both the _id and the subdocument collection id passed to the url
      { "lists._id": id },
      // sets the list object using the position identifier ($) to locate the specific
      // array index and updates it with the variable containing the req.body
      { $set: { "lists.$": listItemUpdate } },
      (err, item) => {
        console.log(item);
        res.send(item);
      }
    );
  });
};