添加markup并清洗输入时遇TypeError: CPASchema.pre is not a function

问题描述 #

尝试为输入添加markup并进行清洗（sanitize）时，持续报错TypeError: CPASchema.pre is not a function，更换mongoose版本后问题仍未解决。

用户代码 #

const mongoose = require('mongoose');
const slug = require('slugify');
const createDomPurify = require('dompurify');
const marked = require('marked');
const {JSDOM} = require('jsdom');
const dompurify = createDomPurify( new JSDOM().window);

const CPASchema = {
   
   //SOME PART OF THIS CODE BUT UNNECESSARY TO THE QUESTION 

    answer:{
        type:String
    },

    sanitizedHTML:{
        type: String,
        required: true
    }
}

CPASchema.pre('validate', async function(data, next){ 

    if(data.answer) {
         console.log('JUST BEFORE SANITIZING')
        data.sanitizedHTML = await dompurify.sanitize(marked(data.answer));
    }
    next()

})

module.exports = mongoose.model('CPASchema', CPASchema);

报错信息 #

CPASchema.pre('validate', async function(data, next){
          ^

TypeError: CPASchema.pre is not a function

解决方案 #

核心问题是你定义的CPASchema只是普通JavaScript对象，并非Mongoose的Schema实例——只有Mongoose Schema实例才具备pre()这类中间件方法。

修改步骤：

• 用mongoose.Schema()将对象转为Schema实例
• 修正中间件参数：Mongoose中间件函数通过this访问当前文档，无需额外传入data参数
• dompurify.sanitize是同步方法，不需要await

修改后的代码：

const mongoose = require('mongoose');
const slug = require('slugify');
const createDomPurify = require('dompurify');
const marked = require('marked');
const {JSDOM} = require('jsdom');
const dompurify = createDomPurify( new JSDOM().window);

// 用mongoose.Schema包装，创建合法的Schema实例
const CPASchema = new mongoose.Schema({
   
   //SOME PART OF THIS CODE BUT UNNECESSARY TO THE QUESTION 

    answer:{
        type:String
    },

    sanitizedHTML:{
        type: String,
        required: true
    }
});

// 修正中间件逻辑：通过this访问文档属性
CPASchema.pre('validate', function(next){ 
    if(this.answer) {
         console.log('JUST BEFORE SANITIZING')
        this.sanitizedHTML = dompurify.sanitize(marked(this.answer));
    }
    next();
});

// 模型名建议用单数形式，Mongoose会自动生成复数集合名
module.exports = mongoose.model('CPA', CPASchema);

内容的提问来源于stack exchange，提问作者Emmanuel Owino