Mongoose schema: Validating unique field, case insensitive

What about using:

{ type: String, lowercase: true, trim: true }

to achieve your purpose?

A collation with strength: 2 on the index solves this issue.

index: {  unique: true,  collation: {    locale: 'en',    strength: 2  }}

Place this in your Schema creation code as follows:

var userSchema = new Schema({  ...  username: {    type: String,    required: true,    index: {      unique: true,      collation: { locale: 'en', strength: 2 }    }});

Note: make sure the index on the model gets updated - you might need to do this manually.

... with mongoose on NodeJS that query:

const countryName = req.params.country;{ 'country': new RegExp(`^${countryName}$`, 'i') };

or

const countryName = req.params.country;{ 'country': { $regex: new RegExp(`^${countryName}$`), $options: 'i' } };// ^australia$

or

const countryName = req.params.country;{ 'country': { $regex: new RegExp(`^${countryName}$`, 'i') } };// ^turkey$

A full code example in Javascript, NodeJS with Mongoose ORM on MongoDB

// get all customers that given country nameapp.get('/customers/country/:countryName', (req, res) => {    //res.send(`Got a GET request at /customer/country/${req.params.countryName}`);    const countryName = req.params.countryName;    // using Regular Expression (case intensitive and equal): ^australia$    // const query = { 'country': new RegExp(`^${countryName}$`, 'i') };    // const query = { 'country': { $regex: new RegExp(`^${countryName}$`, 'i') } };    const query = { 'country': { $regex: new RegExp(`^${countryName}$`), $options: 'i' } };    Customer.find(query).sort({ name: 'asc' })        .then(customers => {            res.json(customers);        })        .catch(error => {            // error..            res.send(error.message);        });});