Remove all except a single field from a nested document via projection in MongoDB

Set the field you don’t want to include as 0. This would display rest of the values while using find(). Let us first create a collection with documents −

> db.demo237.insertOne({
...   _id:101,
...   Product: {
...      description1: {id:1001 },
...      description2: {Name:"Product-1" },
...      description3: {Price:550 }
...   }
...}
...);
{ "acknowledged" : true, "insertedId" : 101 }

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

> db.demo237.find().pretty();

This will produce the following output −

{
   "_id" : 101,
   "Product" : {
      "description1" : {
         "id" : 1001
      },
      "description2" : {
         "Name" : "Product-1"
      },
      "description3" : {
         "Price" : 550
      }
   }
}

Following is the query to remove all except a single field from a nested document via projection −

> db.demo237.find({}, { "Product.description1": 0, "Product.description3": 0 });

This will produce the following output −

{ "_id" : 101, "Product" : { "description2" : { "Name" : "Product-1" } } }

AmitDiwan

Published on 30-Mar-2020 16:49:42