Find which MongoDB document contains a specific string?

To find which document contains a specific string, use $regex along with find(). Let us create a collection with documents −

> db.demo597.insertOne({"Name":"John Doe"});{
   "acknowledged" : true, "insertedId" : ObjectId("5e947ae3f5f1e70e134e2690")
}
> db.demo597.insertOne({"Name":"John Smith"});{
   "acknowledged" : true, "insertedId" : ObjectId("5e947ae8f5f1e70e134e2691")
}
> db.demo597.insertOne({"Name":"Chris Brown"});{
   "acknowledged" : true, "insertedId" : ObjectId("5e947aeff5f1e70e134e2692")
}
> db.demo597.insertOne({"Name":"Adam Smith"});{
   "acknowledged" : true, "insertedId" : ObjectId("5e947afff5f1e70e134e2693")
}

Display all documents from a collection with the help of find() method −

> db.demo597.find();

This will produce the following output −

{ "_id" : ObjectId("5e947ae3f5f1e70e134e2690"), "Name" : "John Doe" }
{ "_id" : ObjectId("5e947ae8f5f1e70e134e2691"), "Name" : "John Smith" }
{ "_id" : ObjectId("5e947aeff5f1e70e134e2692"), "Name" : "Chris Brown" }
{ "_id" : ObjectId("5e947afff5f1e70e134e2693"), "Name" : "Adam Smith" }

Following is the query to find which MongoDB document contains a specific string −

> db.demo597.find({Name:{$regex:/smith/i}} );

This will produce the following output −

{ "_id" : ObjectId("5e947ae8f5f1e70e134e2691"), "Name" : "John Smith" }
{ "_id" : ObjectId("5e947afff5f1e70e134e2693"), "Name" : "Adam Smith" }