Mongoose API无法读取请求体数组字段，MongoDB数组字段为空

使用Mongoose创建API提交数据到MongoDB，其中包含数组类型字段images。尝试在请求体中以字符串形式（如"['image','image2']"）和原生数组形式传递，但服务器端始终无法读取该字段，req.body.images返回undefined，最终存入MongoDB的images字段始终为空，其他字段可正常存储。

请求Payload #

{
    "name": "name",
    "description": "description",
    "price": 123,
    "image_array": "['image','image2']",
    "category": "category",
    "country": "country",
    "city": "city",
    "thumbnail": "thumbnail"
}

响应 #

{
    "data": {
        "name": "name",
        "description": "description",
        "price": 123,
        "thumbnail": "thumbnail",
        "images": [],
        "category": "category",
        "country": "country",
        "city": "city",
        "user": "633710ae6238121bd9ff4f46",
        "status": "active",
        "likes": 0,
        "_id": "633c794ef9449f8b86c948b0",
        "createdAt": "2022-10-04T18:19:58.440Z",
        "updatedAt": "2022-10-04T18:19:58.440Z",
        "__v": 0
    },
    "message": "Product added successfully",
    "Array_type": "undefined"
}

路由代码 #

router.post("/", async (req, res) => {
  console.log("post product");
  try {
    const newProduct = new Product({
      name: req.body.name,
      description: req.body.description,
      price: req.body.price,
      image: req.body.image,
      category: req.body.category,
      country: req.body.country,
      city: req.body.city,
      user: req.user._id,
      thumbnail: req.body.thumbnail,
    });

    data = await newProduct.save();
    res.status(200).json({
      data,
      message: "Product added successfully",
      Array_type: typeof req.body.images,
    });
  } catch (err) {
    console.log(err);
    res.status(500).json(err);
  }
});

Product Schema #

const ProductSchema = new mongoose.Schema(
  {
    name: { type: String, required: true },
    description: { type: String, required: true },
    price: { type: Number, required: true },
    thumbnail: { type: String, required: true },
    images: [String],
    category: { type: String, required: true },
    country: { type: String },
    city: { type: String },
    user: { type: mongoose.Schema.Types.ObjectId, ref: "User" },
    status: { type: String, default: "active" },
    likes: { type: Number, default: 0 },
    createdAt: { type: Date, default: Date.now },
    updatedAt: { type: Date, default: Date.now },
  },
  { timestamps: true }
);

解决方案 #

1. 字段名不匹配问题 #

请求Payload中传递的字段是image_array，但路由中尝试读取的是req.body.images，Schema定义的字段也是images，三者不统一。

修正方式二选一：

• 修改请求Payload，将image_array改为images，传递原生JSON数组（推荐）：

  {
      "name": "name",
      "description": "description",
      "price": 123,
      "images": ["image","image2"],
      "category": "category",
      "country": "country",
      "city": "city",
      "thumbnail": "thumbnail"
  }
  

• 或者在路由中读取req.body.image_array，将字符串形式的数组解析为真实数组（注意替换单引号为双引号，否则JSON.parse会报错）：

  const images = req.body.image_array ? JSON.parse(req.body.image_array.replace(/'/g, '"')) : [];
  

2. 路由代码未写入images字段 #

当前路由创建newProduct时完全没有包含images字段，导致即使请求传对值也无法存入数据库，需添加该字段：

情况一：请求传递原生数组

修改路由代码：

router.post("/", async (req, res) => {
  console.log("post product");
  try {
    const newProduct = new Product({
      name: req.body.name,
      description: req.body.description,
      price: req.body.price,
      image: req.body.image,
      category: req.body.category,
      country: req.body.country,
      city: req.body.city,
      user: req.user._id,
      thumbnail: req.body.thumbnail,
      images: req.body.images || [] // 添加这一行
    });

    data = await newProduct.save();
    res.status(200).json({
      data,
      message: "Product added successfully",
      Array_type: typeof req.body.images,
    });
  } catch (err) {
    console.log(err);
    res.status(500).json(err);
  }
});

情况二：请求传递字符串形式数组

修改路由代码，先解析字符串为数组：

router.post("/", async (req, res) => {
  console.log("post product");
  try {
    let images = [];
    if (req.body.image_array) {
      try {
        images = JSON.parse(req.body.image_array.replace(/'/g, '"'));
      } catch (parseErr) {
        console.log("解析images失败:", parseErr);
        images = [];
      }
    }

    const newProduct = new Product({
      name: req.body.name,
      description: req.body.description,
      price: req.body.price,
      image: req.body.image,
      category: req.body.category,
      country: req.body.country,
      city: req.body.city,
      user: req.user._id,
      thumbnail: req.body.thumbnail,
      images: images
    });

    data = await newProduct.save();
    res.status(200).json({
      data,
      message: "Product added successfully",
      Array_type: typeof images,
    });
  } catch (err) {
    console.log(err);
    res.status(500).json(err);
  }
});

3. 验证body-parser配置 #

确保Express应用已正确配置express.json()中间件，否则无法解析JSON格式请求体：

const express = require('express');
const app = express();

app.use(express.json()); // 必须添加这一行

内容的提问来源于stack exchange，提问作者Alex