Using a regex with text search in MongoDB

To filter records using Regular Expression in MongoDB, use the $regex operator. This allows you to search for documents that match specific text patterns within string fields.

Syntax

db.collection.find({
    "fieldName": {
        $regex: /pattern/,
        $options: "flags"
    }
});

Sample Data

Let's create a collection with sample documents ?

db.demo19.insertMany([
    {"Values": "4321GH"},
    {"Values": "12321_Carol"},
    {"Values": "8765Mike"}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e1389b955d0fc6657d21f0f"),
        ObjectId("5e1389c755d0fc6657d21f10"),
        ObjectId("5e1389d355d0fc6657d21f11")
    ]
}

Example: Using $regex with OR Pattern

Search for documents containing either "4321" or "8765" in the Values field ?

db.demo19.find({
    Values: {
        $regex: /4321|8765/,
        $options: 'i'
    }
});

{ "_id": ObjectId("5e1389b955d0fc6657d21f0f"), "Values": "4321GH" }
{ "_id": ObjectId("5e1389d355d0fc6657d21f11"), "Values": "8765Mike" }

Key Points

• The | operator in regex creates an OR condition between patterns
• $options: 'i' makes the search case-insensitive
• Use forward slashes /pattern/ for regex literals or string format with escaped characters

Conclusion

The $regex operator enables powerful pattern matching in MongoDB queries. Use the pipe (|) symbol for OR conditions and $options for additional regex flags like case-insensitive matching.