更新时如何执行PRE保存挂钩功能

发布于 2025-01-20 20:54:24 字数 542 浏览 1 评论 0原文

在我的文档中，我有一些名为身高、体重、BMI的属性。我使用预保存挂钩来计算和存储文档创建或保存时的BMI。但我想在身高或体重更新时更新 BMI。

//这是我使用的预保存钩子

studentSchema.pre('save', function (next) {
  this.bmi = calcBMI(this.height, this.weight);
  next();
});

//BMI计算函数

exports.calcBMI = (height, weight) => {
  const heightInMeters = height / 100;
  const bmi = (weight / heightInMeters ** 2).toFixed(2);
  return bmi;
};

这个函数在我创建新学生时效果很好。

原文

In my document I have some properties called height, weight, BMI. I used the pre save hook to calculate and store the BMI on document create or save. But I want to Update the BMI whenever the height or weight is updated.

//this is the pre save hook that I used

studentSchema.pre('save', function (next) {
  this.bmi = calcBMI(this.height, this.weight);
  next();
});

//BMI Calculating Function

exports.calcBMI = (height, weight) => {
  const heightInMeters = height / 100;
  const bmi = (weight / heightInMeters ** 2).toFixed(2);
  return bmi;
};

This function works well when I create a new student.

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仲春光 2025-01-27 20:54:24

您必须在架构中使用Mongoose Setters，例如：

const studentSchema = new Schema({
  weight: {
    type: Number,
    set: () => this.bmi = calcBMI(this.height, this.weight);
  },
...same with height
});

官方Mongoose页面： >

you have to use mongoose setters in schema like:

const studentSchema = new Schema({
  weight: {
    type: Number,
    set: () => this.bmi = calcBMI(this.height, this.weight);
  },
...same with height
});

official mongoose page: mongoose setters page

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感受沵的脚步 2025-01-27 20:54:24

您可以在文档属性上使用 isModified() 辅助函数并检查它是否发生更改

studentSchema.pre('save', function (next) {
  const std = this;
  if(std.isModified("height") || std.isModified("weight")){
   this.bmi = calcBMI(this.height, this.weight)
}
  next();
});

You can use isModified() helper function on a document property and check if it's change or not

studentSchema.pre('save', function (next) {
  const std = this;
  if(std.isModified("height") || std.isModified("weight")){
   this.bmi = calcBMI(this.height, this.weight)
}
  next();
});

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