Best way to wrap mongoose validation error - node.js

Question

We know that mongoose provides us an easy way to do validation. But suppose you are using express+mongoose to building a microservice; and some clients (could be web-app, mobile app etc.) needs to consume it.
Usually, I prefer to response JSON back with simple error code and message. In most cases, the clients who can create their own messages depending on which language they are showing to users.
By default, if we catch the error from mongoose, we can get JSON response such as:
JSON Response
{
"errors": {
"price": {
"message": "Path `price` (-1) is less than minimum allowed value (0).",
"name": "ValidatorError",
"properties": {
"min": 0,
"type": "min",
"message": "Path `{PATH}` ({VALUE}) is less than minimum allowed value (0).",
"path": "price",
"value": -1
},
"kind": "min",
"path": "price",
"value": -1,
"$isValidatorError": true
},
"code": {
"message": "Product with given code already exists",
"name": "ValidatorError",
"properties": {
"type": "user defined",
"message": "Product with given code already exists",
"path": "code",
"value": "p-1000"
},
"kind": "user defined",
"path": "code",
"value": "p-1000",
"$isValidatorError": true
}
},
"_message": "Product validation failed",
"message": "Product validation failed: price: Path `price` (-1) is less than minimum allowed value (0)., code: Product with given code already exists",
"name": "ValidationError"
}
Restful Api Controller
exports.createOne = async(function* list(req, res) {
try {
const product = new Product(req.body)
const newProduct = yield product.save()
res.json(newProduct)
} catch (err) {
res.status(400).json(err)
}
})
Model Product.js
const mongoose = require('mongoose')
const Schama = mongoose.Schema
const minlength = [5, 'The value of `{PATH}` (`{VALUE}`) is shorter than the minimum allowed length ({MINLENGTH}).'];
const ProductSchema = new Schama({
code: { type: String, required: true, minlength, index: true, unique: true, trim: true, lowercase: true },
name: { type: String, required: true, trim: true },
price: { type: Number, required: true, min: 0, max: 100000 },
categories: [String],
})
ProductSchema.path('code').validate(function uniqueEmail(code, fn) {
const Product = mongoose.model('Product')
// Check only when it is a new Product or when code field is modified
if (this.isNew || this.isModified('code')) {
Product.find({ code }).exec((err, products) => {
fn(!err && products.length === 0)
})
} else fn(true)
}, 'Product with given code already exists')
ProductSchema.statics = {
/**
* List products
*
* #param {Object} options
* #api private
*/
pageList: function pageList(conditions, index, size) {
const criteria = conditions || {}
const page = index || 0
const limit = size || 30
return this.find(criteria)
.populate('user', 'name username')
.sort({ createdAt: -1 })
.limit(limit)
.skip(limit * page)
.exec()
},
}
mongoose.model('Product', ProductSchema)
What I expect
I am trying to wrap the error message to make it simple to consumer.
It could be like:
{
"errors": [
{
"message": "Path `price` (-1) is less than minimum allowed value (0).",
"code": "100020"
},
{
"message": "Product with given code already exists",
"code": "100021"
}
],
"success": false
}
The code and the corresponding message will be maintained on api documents. The message is usualy useful for consumer to understand the code and consumer (such as web client) could create their own message such as French messages according to the code and show to end users.
How can I leverage mongoose's valiation to accomplish this? Maybe I could loop erros's properties and combine an code using ${path}-${kind}.
I know that in most case, Client side should do the validation before calling apis. But there must be some cases that errors have to be thrown by APIs.
Any idea for this?