Node.js and Mongoose regex query on multiple fields - regex

Question

I would like to query multiple fields using the same regular expression for both. In this query, I would like to accept a single text input and check both the firstName and lastName fields for results. I can query a single field just fine using the regex function in the mongoose documentation, but the syntax for an 'or' clause is giving me trouble.
var re = new RegExp(req.params.search, 'i');
app.User.find().or([{ 'firstName': { $regex: re }}, { 'lastName': { $regex: re }}]).sort('title', 1).exec(function(err, users) {
res.json(JSON.stringify(users));
});
(I'm running mongoose 2.7.1 on node.js 0.6.12)

Answer 1

The code above works fine for a query on multiple fields. Turns out I had some bad data.

Answer 2

My solution is to use $function that allows you to concatenate multiple fields and match their combined value against your regular expression.
const { search } = req.params;
var regex = new RegExp(`.*${search}.*`, 'i');
app.User.find({
$expr: {
$function: {
body: `function(firstName, lastName) { return (firstName+' '+lastName).match(${regex}) }`,
args: ['$firstName', '$lastName'],
lang: "js"
}
}
})
.exec((err, users) => {
res.json(JSON.stringify(users));
});