当试图将注册表保存到MongoDB中时，node不会保存它，除非选择了图像。我希望此参数是可选的，而不是必需的。

router.post("/", upload.single("image"), async (req, res) => {
  const post = new Post({
    title: req.body.title,
    category: req.body.category,
    content: req.body.content,
    video: req.body.video,
    **image: req.file.filename,**
  });
  try {
    const savedPost = await post.save();
    res.redirect("/");
  } catch (e) {
    console.log(e);
  }
});

下面是mongodb模式

const mongoose = require("mongoose");

const PostSchema = new mongoose.Schema({
  title: {
    type: String,
    required: true,
    min: 3,
    max: 255,
  },
  image: {
    type: String,
    required: false,
  },
  category: {
    type: String,
    required: false,
  },
  content: {
    type: String,
  },
  video: {
    type: String,
  },
  uploadDate: {
    type: Date,
    default: () => Date.now(),
  },
});

module.exports = mongoose.model("Post", PostSchema);

下面是错误：映像：请求文件，文件名，^
TypeError：无法读取undefined的属性（阅读“filename”）