Mongoose query hook, modify all incoming dates - mongodb

Question

I have a MEAN app, and I have lots of dates stored in the mongodb, the clock is changing in the UK on 27th October, so all of the dates stored in the db need to have one hour added.
I wouldn't like to loop through all docs in the db and add an hour to its dates, I'd prefer that to be dynamic, so I'm trying to implement a query hook to check each date on the incoming docs and the timezone offset attached in the doc to add/subtract the timezone offset.
The problem is that I'd like the loop on the incoming docs to dynamically identify where the dates are, which will be sometimes on the root of the doc, buried inside an object or an array, which I'm having a hard time to model the loop to check all of that.
I'm using functions to check if the incoming object is a date, an object or an array, but mongoose is adding a bunch of objects/functions that are hindering the operation, so I'm getting RangeError: Maximum call stack size exceeded
const config = require('../config/environment');
var UK_TIMEZONE_GMT_OFFSET = config.UK_TIMEZONE_GMT_OFFSET || 0; // should check if the offset is the same as in each document in the db, if it doesn't match then I'll subtract the offset.
const mongoose = require('mongoose');
const exec = mongoose.Query.prototype.exec;
const Q = require('Q');
mongoose.Query.prototype.exec = function () {
var d = Q.defer();
var p = exec.apply(this, arguments);
if (p) p.then(function (rs) {
var mod;
try {
mod = fixDates(rs);
} catch (err) {
console.log(err, rs)
};
d.resolve(mod);
}, d.reject);
return d.promise;
}
function fixDates(rs) {
if (isArray(rs)) {
rs.forEach(function (r, i) {
rs[i] = fixDates(r);
})
} else if (isObject(rs)) {
for (var key in rs) {
var val = rs[key];
if (isObject(val)) console.log('isobject', isObject(val), val);
// the '_id' of the document is considered an object
// also some stuff like Schema, NativeCollection ... are objects as well
// rs[key] = fixDates(val); // this line causes problems
}
} else if (isDate(rs)) {
// modify the date if necessary ..
// Check the timezone offset of the document vs the global timezone offset
of the system then add/subtract the difference
}
return rs;
}
function isDate(obj) {
return obj instanceof Date;
}
function isObject(obj) {
return Object.prototype.toString.call(obj) === '[object Object]';
}
function isArray(obj) {
return Array.isArray(obj);
}
I need better methodology to deal with mongoose returned object in order to loop through all documents and deeply find the dates and modify them.

Answer 1

I updated the recurring function to invoke model.toObject if exists and apply the update the date fields, while still keeping the model class
function recur(rs, docTimezone) {
if (isArray(rs)) {
rs.forEach(function (r, i) {
rs[i] = recur(r, docTimezone);
})
} else if (isObject(rs)) {
if (rs.toObject) {
return updateModel(rs, recur(rs.toObject(), docTimezone))
}
Object.keys(rs).forEach(function (key) {
var val = rs[key];
rs[key] = recur(val, docTimezone !== undefined ? docTimezone : rs.usedTimezoneGMTOffset); // usedTimezoneGMTOffset if exists on the doc
})
} else if (isDate(rs)) {
// modify the date if necessary ..
rs = alignTimezone(rs, docTimezone);
}
return rs;
}
function updateModel(model, updates) {
var key, val;
for (key in updates) {
val = updates[key];
if (val !== void 0 && key !== '_id') {
model[key] = val;
}
}
return model;
}