Check if a field contains a string in MongoDB?

You can use the $regex operator to check if a field contains a string in MongoDB. This allows pattern matching and substring searches within document fields.

Syntax

db.collection.find({ "fieldName": { $regex: ".*searchString.*" } });

Sample Data

db.checkFieldContainsStringDemo.insertMany([
    { "Id": 1, "Name": "John" },
    { "Id": 2, "Name": "Johnson" },
    { "Id": 3, "Name": "Carol" },
    { "Id": 4, "Name": "Mike" },
    { "Id": 5, "Name": "Sam" },
    { "Id": 6, "Name": "Larry" }
]);

{
    "acknowledged": true,
    "insertedIds": {
        "0": ObjectId("5c77d762fc4e719b197a12ed"),
        "1": ObjectId("5c77d76bfc4e719b197a12ee"),
        "2": ObjectId("5c77d774fc4e719b197a12ef"),
        "3": ObjectId("5c77d77cfc4e719b197a12f0"),
        "4": ObjectId("5c77d784fc4e719b197a12f1"),
        "5": ObjectId("5c77d78cfc4e719b197a12f2")
    }
}

Example 1: Find Documents Containing "John"

Search for names containing the substring "John" ?

db.checkFieldContainsStringDemo.find({ "Name": { $regex: ".*John.*" } });

{ "_id": ObjectId("5c77d762fc4e719b197a12ed"), "Id": 1, "Name": "John" }
{ "_id": ObjectId("5c77d76bfc4e719b197a12ee"), "Id": 2, "Name": "Johnson" }

Example 2: Case-Insensitive Search

Use the $options parameter for case-insensitive matching ?

db.checkFieldContainsStringDemo.find({ 
    "Name": { $regex: "john", $options: "i" } 
});

{ "_id": ObjectId("5c77d762fc4e719b197a12ed"), "Id": 1, "Name": "John" }
{ "_id": ObjectId("5c77d76bfc4e719b197a12ee"), "Id": 2, "Name": "Johnson" }

Key Points

• .*pattern.* matches any string containing the pattern anywhere
• $options: "i" enables case-insensitive matching
• $regex supports full regular expression syntax for complex patterns

Conclusion

The $regex operator provides flexible string matching in MongoDB. Use .*pattern.* for substring searches and add $options: "i" for case-insensitive queries to find documents containing specific text patterns.