How to trim spaces from field in MongoDB query?

To trim spaces from field in MongoDB, use the $trim operator within an aggregation pipeline. The $trim operator removes whitespace characters from the beginning and end of a string.

Syntax

db.collection.aggregate([
   { $project: { 
       fieldName: { $trim: { input: "$sourceField" } }
   }}
])

Sample Data

db.demo217.insertMany([
   {"FullName": "   Chris Brown"},
   {"FullName": "   David Miller"},
   {"FullName": "   John Doe"}
]);

{
   "acknowledged": true,
   "insertedIds": [
      ObjectId("5e3e5d1e03d395bdc213470f"),
      ObjectId("5e3e5d2503d395bdc2134710"), 
      ObjectId("5e3e5d2b03d395bdc2134711")
   ]
}

Display all documents to see the original data with spaces ?

db.demo217.find();

{ "_id": ObjectId("5e3e5d1e03d395bdc213470f"), "FullName": "   Chris Brown" }
{ "_id": ObjectId("5e3e5d2503d395bdc2134710"), "FullName": "   David Miller" }
{ "_id": ObjectId("5e3e5d2b03d395bdc2134711"), "FullName": "   John Doe" }

Example: Trim Spaces Using $trim

Use the $trim operator in aggregation to remove leading and trailing spaces ?

db.demo217.aggregate([
   { $project: { Name: { $trim: { input: "$FullName" } } } }
]);

{ "_id": ObjectId("5e3e5d1e03d395bdc213470f"), "Name": "Chris Brown" }
{ "_id": ObjectId("5e3e5d2503d395bdc2134710"), "Name": "David Miller" }
{ "_id": ObjectId("5e3e5d2b03d395bdc2134711"), "Name": "John Doe" }

Key Points

• $trim only works within aggregation pipelines, not in regular find queries.
• The operator removes whitespace from both ends but preserves internal spaces.
• Use $project to create a new field with trimmed values.

Conclusion

The $trim operator effectively removes leading and trailing whitespace from string fields in MongoDB. Use it within aggregation pipelines with $project to clean up field values while preserving the original data structure.