Search a sub-field on MongoDB?

To search a sub-filed in MongoDB, you can use double quotes along with dot notation. Let us first create a collection with documents −

> db.searchSubFieldDemo.insertOne(
...   {
...      "UserDetails":
...      {"UserEmailId":"John123@gmail.com","UserAge":21}
...   }
... );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd3d909edc6604c74817ce2")
}
> db.searchSubFieldDemo.insertOne( { "UserDetails": {"UserEmailId":"Carol@yahoo.com","UserAge":26} } );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd3d9a4edc6604c74817ce3")
}

Following is the query to display all documents from a collection with the help of find() method −

> db.searchSubFieldDemo.find().pretty();

This will produce the following output −

{
   "_id" : ObjectId("5cd3d909edc6604c74817ce2"),
   "UserDetails" : {
      "UserEmailId" : "John123@gmail.com",
      "UserAge" : 21
   }
}
{
   "_id" : ObjectId("5cd3d9a4edc6604c74817ce3"),
   "UserDetails" : {
      "UserEmailId" : "Carol@yahoo.com",
      "UserAge" : 26
   }
}

Following is the query to search a sub-field on MongoDB −

> db.searchSubFieldDemo.find({"UserDetails.UserEmailId":"Carol@yahoo.com"});

This will produce the following output −

{ "_id" : ObjectId("5cd3d9a4edc6604c74817ce3"), "UserDetails" : { "UserEmailId" : "Carol@yahoo.com", "UserAge" : 26 } }