Within this scenario, I have two distinct models: Protocol and Comment. Each model incorporates a middleware ('pre' or 'remove') that triggers the other model. The issue arises when attempting to call the Comment middleware in Comment.js as it halts at Protocol.findById(). This is due to Protocol being recognized as an object rather than a model function.
Protocol : [object Object] Type : object
Upon removing
const Comment = require('../models/comment')Protocol : function model(doc, fields, skipId) {
model.hooks.execPreSync('createModel', doc);
if (!(this instanceof model)) {
return new model(doc, fields, skipId);
}
Model.call(this, doc, fields, skipId);
} Type : function
The behavior exhibited here is perplexing. Even more puzzling is the fact that while the Protocol.js middleware operates flawlessly, despite Comment.js containing
const Protocol = require('../models/protocol')A workaround was discovered in another discussion thread, recommending to substitute Protocol.findById() within the middleware with
mongoose.model('Protocol').findById()Below are the scripts provided. If additional information is required, kindly let me know, and I will furnish it promptly. Thank you.
Protocol.js model & middleware
// Dependencies
const mongoose = require('mongoose')
//Models
//<!---- If Comment is not required here then the Comment Middleware works ---->!
const Comment = require('../models/comment')
//Schema
const protocolSchema = mongoose.Schema({
_id : mongoose.Schema.Types.ObjectId,
title: {
type : String,
required: true
},
comments : [{
type: mongoose.Schema.Types.ObjectId,
ref : 'Comment',
}]
})
//Middleware Hook Call
protocolSchema.pre('remove', async function() {
console.log('Starts Protocol.schema.pre(\'remove\')')
var toBeDeletedProtocol = this
await removeComments()
function removeComments(){
return new Promise ((resolve, reject) => {
console.log('Starts removeComments()')
var deletedComments = []
Comment.find({protocol : toBeDeletedProtocol._id})
.exec()
.then( comments => {
console.log('comments found: ' + comments)
return resolve()
})
.catch(err => {
console.log('Removing comment(s) related to the deleted protocol failed in protocol remove Hook')
return reject(err)
})
})
}
})
//Model Export
module.exports = mongoose.model('Protocol', protocolSchema)
Comment.js model & middleware
//Dependencies
const mongoose = require('mongoose')
//Models
const Protocol = require('../models/protocol')
//Schema
const commentSchema = mongoose.Schema(
{
_id : mongoose.Schema.Types.ObjectId,
content: {
type: String,
required : true
},
protocol : {
type: mongoose.Schema.Types.ObjectId,
ref : 'Protocol',
required : true,
}
}
)
//Middleware Hook Call
commentSchema.pre('save', async function() {
console.log('Starts Comment.schema.pre(\'save\')')
var toBeSavedComment = this
await updateProtocol()
function updateProtocol(){
return new Promise ((resolve, reject) => {
console.log('Starts updateProtocol()')
console.log('toBeSavedComment : '+ toBeSavedComment)
console.log('Protocol : '+ Protocol, 'Type : ' + typeof Protocol)
//<!----- the ERROR occurs here -----!>
Protocol.findById(toBeSavedComment.protocol)
//<!----- Protocol is seen as an object instead of a model function -----!>
.exec()
.then( protocol => {
console.log('protocol found : ' + protocol)
return resolve()
})
.catch(err => {
console.log('Error in updateProtocol() in Comment.schema pre \'save\'')
console.log(err)
return reject(err)
})
})
}
})
//Export
module.exports = mongoose.model('Comment', commentSchema
)
Package.json
{
"name": "debug",
"version": "1.0.0",
"description": "",
"main": "app.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "node server.js"
},
"author": "",
"license": "ISC",
"dependencies": {
"body-parser": "^1.18.3",
"express": "^4.16.4",
"mongoose": "^5.3.2",
"nodemon": "^1.18.4"
}
}