MongoDB: Is it possible to make a case-insensitive query?

UPDATE:

The original answer is now obsolete. Mongodb now supports advanced full text searching, with many features.

ORIGINAL ANSWER:

It should be noted that searching with regex's case insensitive /i means that mongodb cannot search by index, so queries against large datasets can take a long time.

Even with small datasets, it's not very efficient. You take a far bigger cpu hit than your query warrants, which could become an issue if you are trying to achieve scale.

As an alternative, you can store an uppercase copy and search against that. For instance, I have a User table that has a username which is mixed case, but the id is an uppercase copy of the username. This ensures case-sensitive duplication is impossible (having both "Foo" and "foo" will not be allowed), and I can search by id = username.toUpperCase() to get a case-insensitive search for username.

If your field is large, such as a message body, duplicating data is probably not a good option. I believe using an extraneous indexer like Apache Lucene is the best option in that case.

db.company_profile.find({ "companyName" : { "$regex" : "Nilesh" , "$options" : "i"}});

For searching a variable and escaping it:

const escapeStringRegexp = require('escape-string-regexp')
const name = 'foo'
db.stuff.find({name: new RegExp('^' + escapeStringRegexp(name) + '$', 'i')})   

Escaping the variable protects the query against attacks with '.*' or other regex.

escape-string-regexp

You can use Case Insensitive Indexes:

The following example creates a collection with no default collation, then adds an index on the name field with a case insensitive collation. International Components for Unicode

/* strength: CollationStrength.Secondary
* Secondary level of comparison. Collation performs comparisons up to secondary * differences, such as diacritics. That is, collation performs comparisons of 
* base characters (primary differences) and diacritics (secondary differences). * Differences between base characters takes precedence over secondary 
* differences.
*/
db.users.createIndex( { name: 1 }, collation: { locale: 'tr', strength: 2 } } )

To use the index, queries must specify the same collation.

db.users.insert( [ { name: "Oğuz" },
                            { name: "oğuz" },
                            { name: "OĞUZ" } ] )

// does not use index, finds one result
db.users.find( { name: "oğuz" } )

// uses the index, finds three results
db.users.find( { name: "oğuz" } ).collation( { locale: 'tr', strength: 2 } )

// does not use the index, finds three results (different strength)
db.users.find( { name: "oğuz" } ).collation( { locale: 'tr', strength: 1 } )

or you can create a collection with default collation:

db.createCollection("users", { collation: { locale: 'tr', strength: 2 } } )
db.users.createIndex( { name : 1 } ) // inherits the default collation

If you're using MongoDB Compass:

Go to the collection, in the filter type -> {Fieldname: /string/i}

For Node.js using Mongoose:

Model.find({FieldName: {$regex: "stringToSearch", $options: "i"}})

I'm surprised nobody has warned about the risk of regex injection by using /^bar$/i if bar is a password or an account id search. (I.e. bar => .*@myhackeddomain.com e.g., so here comes my bet: use \Q \E regex special chars! provided in PERL

db.stuff.find( { foo: /^\Qbar\E$/i } );

You should escape bar variable \ chars with \\ to avoid \E exploit again when e.g. bar = '\E.*@myhackeddomain.com\Q'

Another option is to use a regex escape char strategy like the one described here Javascript equivalent of Perl's \Q ... \E or quotemeta()

Use RegExp, In case if any other options do not work for you, RegExp is a good option. It makes the string case insensitive.

var username = new RegExp("^" + "John" + "$", "i");;

use username in queries, and then its done.

I hope it will work for you too. All the Best.

If there are some special characters in the query, regex simple will not work. You will need to escape those special characters.

The following helper function can help without installing any third-party library:

const escapeSpecialChars = (str) => {
  return str.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
}

And your query will be like this:

db.collection.find({ field: { $regex: escapeSpecialChars(query), $options: "i" }})

Hope it will help!

For any one using Golang and wishes to have case sensitive full text search with mongodb and the mgo godoc globalsign library.

collation := &mgo.Collation{
    Locale:   "en",
    Strength: 2, 
}


err := collection.Find(query).Collation(collation)