Mongoose : custom schema type - node.js

Question

I followed this mongoose documentation on custom schema type, to create a "large string":
"use strict";
const mongoose = require('mongoose')
let STRING_LARGE = (key, options) => {
mongoose.SchemaType.call(this, key, options, 'STRING_LARGE');
};
STRING_LARGE.prototype = Object.create(mongoose.SchemaType.prototype);
STRING_LARGE.prototype.cast = function(val) {
let _val = String(val);
if(!/^[a-zA-Z0-9]{0,400}$/.test(_val)){
throw new Error('STRING_LARGE: ' + val + ' is not a valid STRING_LARGE');
}
return _val; };
module.exports = STRING_LARGE;
And I use it like this in a schema:
"use strict";
const mongoose = require('mongoose');
mongoose.Schema.Types.STRING_LARGE = require('./types/string_large')
const schema = new mongoose.Schema({
details: { type: STRING_LARGE, required: true },
link: { type: STRING_LARGE, required: true }
});
module.exports = schema;
But I get the error :
[path]\schemas[shema.js]:8
details: { type: STRING_LARGE, required: true },
ReferenceError: STRING_LARGE is not defined
at Object. ([path]\schemas[shema.js]:8:24)
...
-------------------------- UPDATE : WORKING CODE --------------------------
use "function ()" instead of "() =>"
"use strict";
const mongoose = require('mongoose')
function STRING_LARGE (key, options) {
mongoose.SchemaType.call(this, key, options, 'STRING_LARGE');
};
STRING_LARGE.prototype = Object.create(mongoose.SchemaType.prototype);
STRING_LARGE.prototype.cast = function(val) {
let _val = String(val);
if(!/^[a-zA-Z0-9]{0,400}$/.test(_val)){
throw new Error('STRING_LARGE: ' + val + ' is not a valid STRING_LARGE');
}
return _val; };
use "mongoose.Schema.Types.LARGE_STRING" instead of "LARGE_STRING"
module.exports = STRING_LARGE;
"use strict";
const mongoose = require('mongoose');
mongoose.Schema.Types.STRING_LARGE = require('./types/string_large')
const schema = new mongoose.Schema({
details: { type: mongoose.Schema.Types.STRING_LARGE, required: true },
link: { type: mongoose.Schema.Types.STRING_LARGE, required: true }
});
module.exports = schema;

Answer 1

You are assigning your type to mongoose.Schema.Types.STRING_LARGE and then use STRING_LARGE - that's where your ReferenceError is thrown. You have to use your type directly:
const schema = new mongoose.Schema({
details: { type: mongoose.Schema.Types.STRING_LARGE, required: true },
link: { type: mongoose.Schema.Types.STRING_LARGE, required: true }
});