How can I use a regex variable in a query for MongoDB

Question

I would like to make query MongoDB for documents based on a regex expression that I contruct. For e.g I have constructed a simple regex as follows that is a combination of a

Answer 1

If you want to use the variable val as a parameter of the query part, you can use $regex, for example:

collection.find({"FirstName": {$regex:val}})

It is not allowed to put $regex in $in operator according to the manual.

If you want to put regular expression object in $in operator, you have to use JavaScript regular expression object, for example:

collection.find({"FirstName": {$in: [/abc/, /123/]}})

By the way, val in /val/ is constant string, not the variable as you defined above.

Answer 2

You need to create a regular expression object from the string using the RegExp constructor as the /.../ syntax is only for use with literals.

var stream = collection.find({"FirstName": new RegExp(val)}).stream();

Answer 3

I was having same problem with my title and after lots of searching, i found this answer Here,

var search = 'Joe';
db.users.find(name: /^search/)
db.users.find(name: {$regex: /^search/});
db.users.find(name: {$regex: "/^" + search + "/"});

The queries above won’t return anything. The solution to this little problem is quite simple:

db.users.find(name: new RegExp(search)) //For substring search, case sensitive. 
db.users.find(name: new RegExp('^' + search + '$')) //For exact search, case sensitive
db.users.find(name: new RegExp(search， ‘i')) //For substring search, case insensitive
db.users.find(name: new RegExp('^' +search + '$', 'i')); //For exact search, case insensitive

Other flags or properties can be added base on reference here

Answer 4

Use the following code to use dynamic value in regex with or operations

{$match: { $or: [{ 'title': { $regex:  request.query.val, $options: 'i'} }, { 'skills_required': { $regex:  request.query.val, $options: 'i'} }] }},

Answer 5

let test = `what your regex should 
search`;

collection.find({
    fieldName: {$regex: test}
}).then(result => red.send(result));

// tested on mongoose but should work on mongodb too