我在模式中有一个代码： 型号

const TypeSchema = new Schema({
  title: {
    type: String,required: [true,'Title field is required'],minlength: 2,maxlength: 128,unique: true
  },...
});

并更新

TypeSchema.pre('findOneAndUpdate',function(next){
  console.log(this.title) // undefined
  this.alt = slug(this.title);
  next();
});

在这里我在this.title中没有定义。

并在api中请求

router.put('/arrivals/products/types/:id',isAuthenticated,async (request,response,next) => {
  jsonPreProcessor.response = response;
  let id = request.params.id;

  let title = request.body.title;

  console.log('router ',title); // title is working
  if (id === undefined) {
    return jsonPreProcessor.error("Id не указан");
  }

  if (title === undefined) {
    return jsonPreProcessor.error("Title не указан");
  }

  Type.findByIdAndUpdate(id,{
    title: title
  },{
    new: true
  }).then(type => {
    return jsonPreProcessor.success(type);
  }).catch(error => {
    return jsonPreProcessor.error(error.message); // here I got an error message that title is undefined (in pre.('findOneAndUpdate'))
  });
});

但是在这里我通常会得到一个标题

也许我使用pre'findOneAndUpdate'不正确？如果可以的话，有人可以帮助我