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.